Topnotch Medical Board Prep Preventive Medicine and Public Health Main Handout PDF - April 2024

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch sin...

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. IMPORTANT LEGAL INFORMATION The handouts, videos and other review materials, provided by Topnotch Medical Board Preparation Incorporated are duly protected by RA 8293 otherwise known as the Intellectual Property Code of the Philippines, and shall only be for the sole use of the person: a) whose name appear on the handout or review material, b) person subscribed to Topnotch Medical Board Preparation Incorporated Program or c) is the recipient of this electronic communication. 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Topnotch review materials are updated every six (6) months based on the current trends and feedback. Please buy all recommended review books and other materials listed below. THIS HANDOUT IS NOT FOR SALE! INSTRUCTIONS To scan QR codes on iPhone and iPad 1. Launch the Camera app on your IOS device 2. Point it at the QR code you want to scan 3. Look for the notification banner at the top of the screen and tap To scan QR codes on Android 1. Install QR code reader from Play Store 2. Launch QR code app on your device 3. Point it at the QR code you want to scan 4. Tap browse website This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. PAGE 58 59 59 60 60 61 61 62 64 65 66 66 67 68 69 71 73 73 74 74 75 75 75 75 76 76 76 76 76 76 77 77 77 EPIDEMIOLOGY PREVENTIVE MEDICINE AND PUBLIC HEALTH By Mark Louie C. Mann, MD Contributors: Marianne Michelle Q. de la Rosa, MD Manuel S. Vidal, RCh, MD Madelaine Johanna L. Abraham, RPh, MD Michael Christian A. Virata, MD Ziara Carmelli G. Tan, MD-MBA TOPIC Epidemiology Concepts of Disease Transmission Communicable Diseases Epidemic Disease Occurrence Epidemiologic Studies Quantifying Risk Measures of Disease Frequency Population Dynamics Research Process Biostatistics Preventive Medicine Health Promotion Wellness Programs for Different Age Groups Occupational Health Programs Health Examination for Workers Haddon matrix Smoking Cessation Program Public Health Universal Health Care Act PhilHealth Health Financing COVID-19 Monkeypox National Tuberculosis Program National Dengue Prevention and Control Program Malaria Food and Waterborne Diseases Prevention and Control Program Tetanus National Rabies Prevention and Control Program Non-Communicable Diseases Nutrition TOPIC Expanded Program on Immunization Newborn Screening Program Integrated Management of Childhood Illness Antimicrobial Stewardship Program HIV/STI Prevention Program Schistosomiasis Control Program Environmental Health Programs Primary Health Care Community Diagnosis Development Goals Basic Family Medicine Concepts and Principles Active Listening Skills The Family as a Unit of Care The Family Life Cycle Impact of Illness in the Family Family Assessment Tools Illness, Death, and Dying Palliative and Hospice Care Miscellaneous Topics Death Certificates Census SWOT Analysis Philippine Herbal Medicinal Plants Biological Waste Management Hospital Color Coding Never Events Data Privacy Act Organizational Acts Types Of Leadership Styles Economics Telemedicine Medical and Dental Services Toxic Features of Selected Agents PAGE 1 2 3 6 8 12 12 14 15 16 30 31 32 35 36 36 37 37 37 39 41 41 46 47 50 51 52 • Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems. • Distribution – concerned with the frequency and pattern of health events in a population o Frequency refers not only to the number of health events such as the number of cases of meningitis or diabetes in a population, but also to the relationship of that number to the size of the population o Pattern refers to the occurrence of health-related events by time, place, and person § Time patterns may be annual, seasonal, weekly, daily, hourly, weekday versus weekend, or any other breakdown of time that may influence disease or injury occurrence § Place patterns include geographic variation, urban/rural differences, and location of work sites or schools § Personal characteristics (Person) include demographic factors which may be related to risk of illness, injury, or disability such as age, sex, marital status, and socioeconomic status, as well as behaviors and environmental exposures • Determinants – the causes and other factors (risk factors) that influence the occurrence of disease and other health-related events o any factor, whether event, characteristic, or other definable entity, that brings about a change in a health condition or other defined characteristic o assess whether groups with different rates of disease differ in their demographic characteristics, genetic or immunologic make-up, behaviors, environmental exposures, or other socalled potential risk factors • Health-related states or events (“disease”) - anything that affects the well-being of a population • Application – applying the knowledge gained by the studies to community-based practice The word epidemiology comes from the Greek words: Epi-meaning on or upon, Demos- meaning people Logos-meaning the study of Dr. Mann 54 55 57 57 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 1 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. MATCH THE TERM TO THE ACTIVITY THAT BEST DESCRIBES IT. YOU SHOULD MATCH ONLY ONE TERM PER ACTIVITY. 1. Compare food histories between A. Distribution persons with Staphylococcus food B. Determinants poisoning and those without. C. Application 2. Compare frequency of brain cancer among anatomists with frequency in general population 3. Mark on a map the residences of all children born with birth defects within 2 miles of a hazardous waste site 4. Graph the number of cases of congenital syphilis by year for the country 5. Recommend that close contacts of a child recently reported with meningococcal meningitis receive Rifampin 6. Tabulate the frequency of clinical signs, symptoms, and laboratory findings among children with chickenpox in Cincinnati, Ohio Principles of Epidemiology in Public Health Practice Third Edition Answers: BBAACA HIGHLIGHTS IN THE HISTORY OF EPIDEMIOLOGY • Hippocrates (400BC): attempted to explain disease occurrence from a rational rather than a supernatural viewpoint • John Graunt (1662): First to employ quantitative methods in describing population vital statistics – recorded descriptive statistics of birth and death data • Edward Jenner (1796) discovered that it is possible to vaccinate against Small Pox using material from Cow Pox • John Snow investigated a cholera epidemic in mid-19th century in London – “Father of field epidemiology” • Koch (late 1800s): Some diseases are caused by living organisms! Koch’s Postulates! • Framing Heart Study (1949): Risk factors for coronary heart disease • Salk (1954): Polio Vaccine • Doll and Peto (Post WWII): Association between smoking and Lung CA • Eradication of small pox (1980) (Dr. Kurt’s notes, from Dr. Ofelia Saniel’s Intro to Epid Lecture, CPH, UPM) Principles of Epidemiology in Public Health Practice Third Edition • Punitive theory o disease was a punishment meted out by an outraged God for the sins of the individual or the race • Humoral theory o matter is made up of four elements – Earth, Air, Fire and Water and these elements have the corresponding qualities of being Cold, Dry, Hot and Moist o represented in the body by four humors – Phlegm, yellow bile, black bile and blood o According to this theory, the equilibrium among these humors characterizes health (eucrasia), and disequilibrium (dyscrasia) characterizes disease • Miasmatic theory o based on the inference that the air arising from certain kinds of ground, especially low, swampy areas, was a cause of disease • Contagion theory o based on the observation that persons could contract infections even if their humors are normally balanced o Contagion passes from one thing to another and is originally caused by infection of the imperceptible particles. Particles are called the seminaria (seeds or seedlets) of contagion Dr. Mann MODERN VIEWS • Germ Theory o proposed by Louis Pasteur (1822 –1895) and Robert Koch (1843 –1910) o postulates that every human disease is caused by a microbe or germ • BEINGS THEORY o Biologic factors and Behavioral factors o Environmental factors o Immunologic factors o Nutritional factors o Genetic factors o Services, Social factors, and Spiritual factors The acronym BEINGS can serve as a mnemonic device for the major categories of risk factors for disease • Genetic factors are among the most difficult to change • Immunologic factors are usually the easiest to change, if effective vaccines are available. Jekel's Epidemiology, Biostatistics and Preventive Medicine USES OF EPIDEMIOLOGIC STUDIES: • To identify the etiology or cause of the disease • To determine of natural history and prognosis of the disease • Identification of risk factors and high-risk groups • Determination of the extent of disease found in the community • Identification of health programs, adequate measures for diagnosis and treatment and prevention of diseases • Evaluation of effectiveness of existing health programs, therapy and preventive measures CLASSICAL VS. CLINICAL EPIDEMIOLOGY CLASSICAL CLINICAL • Population oriented • Study patients in health care settings rather that in • Studies the community community at large origins of health problems (infectious agents, • Goal is to improve the nutrition, environment, prevention, early detection, behavior, social, economic, diagnosis, treatment, and spiritual prognosis, and care of illness in INDIVIDUAL • Interested in discovering PATIENTS who are at risk risk factors that might be for, or already affected by, altered in a population to specific disease prevent or delay disease, injury, and death In community medicine, using a sociological and anthropological lens is highly encouraged, as compared to clinical medicine. Dr. Mann • MULTIPLE CAUSATION THEORY o >1 factor is required to cause the disease • EPIDEMIOLOGIC TRIANGLE/CHAIN/TRIAD o In this model, disease results from the interaction between the agent and the susceptible host in an environment that supports transmission of the agent from a source à host o Consist of: § Host § Environment § Agent Principles of Epidemiology in Public Health Practice Third Edition • COMPONENT CAUSES AND CAUSAL PIE o An individual factor that contributes to cause disease is shown as a piece of a pie. § Component cause – Individual factors (a piece of pie) § Sufficient cause – The complete pie § Necessary causes – It is component cause or a piece of pie that appears in every pie, because without it disease does not occur Dr. Tan CONCEPTS OF DISEASE TRANSMISSION CONCEPTS ON CAUSATION DISEASES ANCIENT VIEWS • Demonic theory o evil spirit entering the body directly and pursuing nefarious action https://sphweb.bumc.bu.edu TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 2 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. • WEB OF CAUSATION o effects never depend on single isolated cause but rather develop as a result of causation in which each link is the result of a complex genealogy and antecedents SUPPLEMENT: Factors of disease causation Q: In the setting po ba of a patient with HIV/AIDS na admitted due to Pneumonia, is the state of having HIV/AIDS po ba considered as a Predisposing factor, reinforcing factor, or a risk factor? If ever po we’re given a question where we have to choose only 1 option A: Best ang Predisposing factor. Again defining it, predisposing factors are the factors which create a state of susceptibility, making the host vulnerable to the agent. Both risk factors and predisposing factors are associated with an increased likelihood of health-related outcomes, the key difference lies in modifiability. Risk factors can often be modified through lifestyle changes or interventions, while predisposing factors are inherent and typically cannot be changed. In the case of having HIV and AIDS unfortunately it is non-modifiable. Dr. Mann https://www.nhp.gov.in/causation-of-diseases_mtl pitt.edu • THE WHEEL THEORY o de-emphasizes the agent as the sole cause of disease o emphasizes the interplay of physical, biological and social (production) environments. It also brings genetics into the mix o visualizes human disease in the form of a wheel, which has a central hub representing the genetic components and the peripheral portion representing the environmental component. o the outer part (environmental component) has spokes (3 in this model) and the environmental component is thus divided into 3 sub components, representing the social, biological and physical components of the environment COMMUNICABLE DISEASES INFECTIOUS DISEASE • a disease caused by a microorganism and therefore potentially infinitely transferable to new individuals. • May or may not be communicable. o Example of non-communicable: disease caused by toxins from food poisoning or infection caused by toxins in the environment, such as tetanus. COMMUNICABLE DISEASE • an infectious disease that is contagious and which can be transmitted from one source to another by infectious bacteria or viral organisms. CONTAGIOUS DISEASE • a very communicable disease capable of spreading rapidly from one person to another by contact or close proximity Wheel model of human-environment interaction. (Redrawn from Mausner JS, Kramer S: Mausner and Bahn epidemiology: an introductory text, ed 2, Philadelphia, 1985, Saunders.) • LEVER OR BALANCE o Environment is the fulcrum. o Any shift in the lever caused by either factor will result in disequilibrium (disease) PHASES OF A COMMUNICABLE DISEASE PRE-PATHOGENIC PHASE PATHOGENIC PHASE Phase before man is involved; Course of disorder in man preliminary interaction of from the first interaction with potential agent, host and the disease, provoking stimuli environmental factors in to the changes in form and disease production function which result or until equilibrium is reached or Everyone is in the period of recovery, defect, disability or pre-pathogenesis death ensues Process in environment Process in man REQUIREMENTS FOR SUCCESSFUL AGENT INVASION • Conditions in the environment must be favorable to the agent. • Suitable reservoir • Susceptible host • Satisfactory portal of entry • Accessibility of portal of exit from the host • Appropriate means of dissemination and transmission to a new host Factors of disease causation • Predisposing factors are the factors which create a state of susceptibility, making the host vulnerable to the agent. These are age, sex and previous illnesses. • Enabling factors are those which assist in the development of (or in recovery from) the disease, e.g., housing conditions, socio-economic status. • Precipitating factors are those which are associated with immediate exposure to the disease agent or onset of disease, e.g., drinking contaminated water, close contact with a case of pulmonary TB. • Reinforcing factors are those which aggravate an already existing disease, e.g. malnutrition, repeated exposures. • Risk factors are the conditions, quality or attributes, the presence of which increases the chances of an individual to have, develop or be adversely affected by a disease process. The risk factor need not necessarily cause the disease but does increase the probability that the person exposed to the factor may get the disease easily. SUPPLEMENT: Na tanong ito nung nakaraan, yan ang chika so I included this sa handout, try to understand lang the different factors in causation Real life question/scenario ELEMENTS OF A COMMUNICABLE DISEASE © Topnotch Medical Board Prep I - AGENT • Any element, substance, or force whether living or non-living, the presence or absence of which can initiate or perpetuate a disease process. TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 3 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. PHYSICAL /MECHANICAL PHYSICAL: Can disorganize function within cells, tissues, organs and the body as a whole; light; sound; heat; cold; radiation MECHANICAL: Chronic friction & other forces which add unusual stress to body CLASSIFICATION OF AGENTS CHEMICAL AGENTS NUTRIENT AGENTS EXOGENOUS: Chemical substances needed to Arise outside of the host sustain life (CHO, CHON, fats, vitamins, • Inhalation of pollutants water) • Ingestion of contaminants, drugs alcohol • Skin Contact BIOLOGIC AGENTS Living Disease Agents: • Bacteria • Virus • Fungi • Protozoa ENDOGENOUS Produced in human • abnormal products- uremia • Serum cholesterol • Hormone disturbance CHARACTERISTICS OF A LIVING AGENT • INHERENT o Physical make up o Chemical component o Antigenic characteristic – ability of an agent to oppose the effect of chemotherapeutic or antibiotic substance • BIOLOGIC o Viability – ability to withstand adverse environmental influence o Growth Requirements – availability of appropriate nutrition, temperature, etc. o Host range – spectrum of animals’ which an agent can invade or infect CHARACTERISTICS OF AGENTS DIRECTLY RELATED TO MAN (HOST): • INFECTIVITY o ability of the agent to invade and multiply (to produce infection; the minimum number of particles or agents required to establish infection in 50% of a group of hosts of the same species (ID50); depends on the following factors: § Viability § Portal of entry § Susceptibility of the host § Susceptible tissues § Body defenses of the host • PATHOGENICITY – capacity of an agent to induce disease which is clinically apparent in an infected host • VIRULENCE – Ability of an agent to produce serious illness; measured in terms of fatality • IMMUNOGENICITY – The ability of an agent to induce immunity, or to stimulate the host to produce defense mechanism • ANTIGENICITY – the ability to combine specifically with the products or effectors of the immune response CONCEPT OF THE “CHAIN OF INFECTION” • traditional epidemiologic triad model holds that infectious diseases result from the interaction of agent, host, and environment • transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host 1. A Causative or etiologic agent ( Infectious agent) 2. A reservoir or source of the causative agent ( Reservoir) 3. A mode of escape from the reservoir ( Portal of Exit) 4. A mode of transmission from the reservoir to the potential new host 5. A mode of entry into the new host ( Portal of Entry) 6. A susceptible host a. Interruption in any stage of the chain, the disease will not develop b. The reservoir and source are identical when transfer is direct from a reservoir to host c. Period of communicability - refers to the time during which an infectious agent can be transmitted directly or indirectly from an infected person to another person, from an infected animal to humans, or from an infected person to animals ✔GUIDE QUESTION Ability of an agent to produce serious illness; measured in terms of fatality A. Immunogenicity B. Antigenicity C. Pathogenicity D. Virulence Mnemonic: “VIRU"lence – Hindi na “BIRU” kasi serious na siya = serious illness. Dr. Virata CHARACTERISTICS OF AGENT DIRECTLY RELATED TO ENVIRONMENT: • RESERVOIR OF INFECTION – man, animals, plants, soil or inanimate organic matter in which an infectious agent multiplies; essential component of the cycle by which an infectious agent maintains and perpetuates itself. • SOURCES OF INFECTION – transfer is often direct from reservoirs à host in which the reservoir is also the source of infection • Carrier status – an infected person who does not have apparent clinical disease but is, nevertheless, a potential source of infection to others • Types of carrier: o Asymptomatic or passive or healthy carriers - those who never experience symptoms despite being infected o Incubatory carriers – those who can transmit the agent during the incubation period before clinical illness begins o Convalescent carriers – those who have recovered from their illness but remain capable of transmitting to others o Chronic carriers – those who continue to harbor a pathogen such as hepatitis B virus or Salmonella Typhi © Topnotch Medical Board Prep SUPPLEMENT: ISOLATION separates sick people with a contagious disease from people who are not sick Isolation would last for the period of communicability of the illness, which varies by disease and the availability of specific treatment. One of the best-known examples of a long-term/chronic carrier was Typhoid Mary, who carried Salmonella typhi. • ISOLATION VS. QUARANTINE QUARANTINE separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick Lasts only as long as necessary to protect the public by: (1) providing public health care (such as immunization or drug treatment/prophylaxis) (2) ensuring that quarantined persons do not infect others if they have been exposed to a contagious disease = known incubation period Dr. Mann TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 4 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. MODE OF TRANSMISSION: • Direct Transmission (person to person) o Direct contact (Touching, biting, kissing & Sexual intercourse) o Droplet spread (spray with relatively large, short-range aerosols produced by sneezing, coughing, or even talking o Contact with soil o Inoculation into skin or mucosa o Transplacental (vertical) • Indirect Transmission o Vehicle borne - objects, food, water, biologic products o Vector borne - mosquitoes, fleas, and ticks o Airborne - dust, droplets carried in air o Fomites VECTORS Vector Aedes sp. Anopheles Culex Sand flies Triatome bugs Lice-body louse Tse-tse flies Blackflies Ticks Mites Synanthropic flies Cockroaches Rodents Snails Pigs Fleas © Topnotch Medical Board Prep Regarding sa transmission of different pathogens, there can be more than 1. Example is covid-19, pwedeng airborne, fomites and even shedding of the virus from the stool. In rabies, it can be BOTH placed in direct contact (dog bite) or through inoculation into skin or mucosa (dog licks a broken wound or though mucous membranes in the eyes, nose or mouth). In Leptospirosis, exposure can also be BOTH direct contact by skin to skin with an infected animal (this explains why occupations such as veterinarian, farm workers, and those who handles animals in laboratories are at risk) or inoculation into the skin or mucosa (when the urine from the infected animals gets in contact to a human). In the exam, the answer would depend on how is it asked (if it’s a casebased question). Pwede ang rabies both for direct contact and inoculation, for leptospirosis applicable for direct contact and inoculation. Dr. Mann • DROPLETS VS. AIRBORNE TRANSMISSION Distance Size of droplets Suspended in air • Droplets Shorter (hence considered direct contact) >5μm No Airborne Longer <5μm Yes Dr. Virata EXAMPLES OF MODE OF TRANSMISSION Vector Disease Direct Transmission Sexually transmitted diseases (STD), Direct contact HIV, Leprosy , Leptospirosis Tuberculosis, Whooping cough, Droplet spread Diphtheria, and respiratory infections Contact with soil Tetanus, Hookworm larvae Inoculation into Rabies and Hepatitis B skin or mucosa TORCH (Toxoplasma, Rubella, Transplacental or Cytomegalovirus, Herpes virus), vertical Hepatitis B, Coxsackie B, HIV, Syphilis, and Varicella Indirect transmission Water – typhoid fever, cholera, polio, hepatitis A Vehicle born Blood- Hepatitis B, malaria, syphilis Organ transplantation cytomegalovirus Vector-borne See table for vector-borne diseases Tuberculosis, influenza, chicken pox, Airborne measles, and Q fever Diphtheria, typhoid fever, bacillary Fomites dysentery, hepatitis A Disease Dengue, Chikungunya, filariasis, zika Malaria Filariasis, Japanese encephalitis, west Nile fever Leishmaniasis Chagas disease (American trypanosomiasis) Typhus fever Sleeping sickness (African trypanosomiasis) Onchocerciasis Lyme disease, rickettsial diseases (spotted and Q fever) Scabies Dysentery, yaws Diarrheal diseases, Intestinal, skin and eye infections Leptospirosis Intermediate host for schistosomiasis Trichinosis Bubonic plague FACTORS AFFECTING COMMUNICABILITY OF BACTERIA • Site of lesion of infected host • Size of inoculum • Chance/ accident of coming in contact with bacterial species or strain • Survival capacity in immune subjects • Ability to survive outside animal body • Ability to multiply and survive in intermediate host or vector • Size of reservoir of infection II – HOST • Individual or other living animal exposed to the agent that affords subsistence or lodgment. • Final outcome may vary from complete recovery to death of the host. STAGES IN THE NATURAL HISTORY OF DISEASE • STAGE OF SUSCEPTIBILITY: o Disease has not developed but the groundwork has been laid by the presence of factors that favor its occurrence o Portal of entry o Risk factors • STAGE OF PRE-SYMPTOMATIC DISEASE: o No manifestation of the disease yet but pathogenic changes have started to occur o Incubation period o Ex: Atherosclerotic changes in coronary vessels prior to any signs and symptoms • STAGE OF CLINICAL DISEASE: o End organ damage has occurred so that there are recognizable signs or symptoms of the disease o The clinical horizon • STAGE OF DISABILITY: o Any limitation in a person’s activities including psychosocial role © Topnotch Medical Board Prep TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 5 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. BRIDGE KIND OF HOST 1. Definitive Host o a host in which the parasite reaches maturity and, if possible, reproduces sexually 2. Reservoir Host o can harbor a pathogen indefinitely with no ill effects 3. Intermediate Host o host that harbors the parasite only for a short transition period, during which (usually) some developmental stage is completed. 4. Paratenic Host o host is similar to an intermediate host, only that it is not needed for the parasite's development cycle to progress. o Paratenic hosts serve as "dumps" for non-mature stages of a parasite in which they can accumulate in high numbers. 5. Dead-end host or incidental host o is an intermediate host that generally does not allow transmission to the definitive host, thereby preventing the parasite from completing its development. 6. Host of predilection o is the host preferred by a parasite 7. Amplifying host o is a host in which the level of pathogen can become high enough that a vector such as a mosquito that feeds on it will probably become infectious Balikan niyo yung micro niyo! Paulit ulit!... J Dr. Mann • DEFENSE MECHANISM OF THE HOST: • Specific anatomical defenses • Immunity • Resistance • Tolerance • Allergy • State of nutrition III – ENVIRONMENT • Sum total of an organism’s external surrounding conditions and influences that affects the life and development of an organism 3 CATEGORIES OF ENVIRONMENT: PHYSICAL BIOLOGIC SOCIO-ECONOMIC Climate Serve as • Working condition reservoirs • Temperature • Level of industrialization and vectors • Disruption: Disaster/ war • Altitude of disease • Humidity • Availability of medical agents services Geography/ • Period of prosperity and Location depression • Sanitation and Housing SUPPLEMENT Burden of Disease (Philippines, 2022) Top 10 Leading Causes of Morbidity 1. Acute Respiratory Infection 2. Hypertension 3. Animal Bites 4. Acute Lower Tract Respiratory Infection 5. Urinary Tract Infection 6. Skin Disease 7. Influenza-like Illness 8. TB All Forms 9. Acute Watery Diarrhea 10. Acute Febrile Illness • EPIDEMIC – an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area. (There MUST be an increase from the baseline!) • OUTBREAK – same definition of epidemic, but is often used for a more limited geographic area • PANDEMIC – refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people (worldwide epidemic) • SPORADIC – refers to a disease that occurs infrequently and irregularly MATCHING TYPE 1. 22 Cases of legionellosis occurred A. Sporadic Disease within 3 weeks among residents of B. Endemic Disease a particular neighborhood (usually C. Hyperendemic 0 or 1 per yr) Disease 2. Average annual incidence was D. Pandemic Disease 364 cases of pulmonary E. Epidemic Disease tuberculosis per 100,000 population in one area, compared with national average of 134 cases per 100,000 3. Over 20M people worldwide died from influenza in 1918-1919 4. Single case of histoplasmosis was diagnosed in a community 5. About 60 cases of gonorrhea are usually reported in this region per week, slightly less than the national average. Principles of Epidemiology in Public Health Practice Third Edition Answers: ECDAB ESSENTIAL INGREDIENTS OF AN EPIDEMIC • A recent increase in dosage or change in virulence of the pathogenic agent • the recent introduction of the pathogen into a setting where it has not been before • an enhanced method of transmission so that more susceptible are exposed • some change in the susceptibility of the host response to the pathogenic agent • cultural or behavioral factors that increase host exposure or involve introduction through new portals of entry GENERATION TIME • The period between the receipt of infection by the host and the maximal communicability of that host. • Roughly equivalent to the incubation period, the interval between the receipt of infection and the onset of illness. • Can be used to measure the rate of an epidemic o When one person transmits an infection to another, then the time that elapses between onset of symptoms in the primary case and onset of symptoms of the secondary case Source: May 2022 FHSIS Preliminary Data, DOH Based on the above data from PSA and DOH the top causes of mortality in the country consists of non-communicable diseases, which can be a result of unhealthy behaviors, modifiable risk factors, and the sociopolitical conditions affecting the communities. Meanwhile, the top leading causes of morbidity are generally communicable diseases influenced heavily by the environmental conditions such as unsafe drinking water, poor sanitation and hygiene and indoor and outdoor air pollution. Dr. Tan EPIDEMIC DISEASE OCCURRENCE DEFINITION OF TERMS • ABSENCE OF DISEASE – no cases on record; disease absent from the beginning or it has been eradicated • ENDEMIC – habitual presence of a disease within a given geographic area, also refers to the usual occurrence of a given disease within such an area • HYPERENDEMIC – refers to persistent, high levels of disease occurrence © Topnotch Medical Board Prep EPIDEMIC CURVES • shows the frequency of new cases over time based on the date of onset of disease • The shape of the curve in relation to the incubation period for a particular disease can give clues about the source TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 6 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. TYPES OF EPIDEMIC PATTERNS • Epidemics can be classified according to their manner of spread through a population: o Common-source § Point § Continuous o Propagated o Mixed o Other PROPAGATED OUTBREAK • results from transmission from one person to another • usually have a series of successively larger peaks, which are one incubation period apart • The successive waves tend to involve more and more people, until the pool of susceptible people is exhausted or control measures are implemented COMMON SOURCE OUTBREAK • one in which a group of persons are all exposed to an infectious agent or a toxin from the same source. POINT-SOURCE OUTBREAK • Type of common-source outbreak – If the group is exposed over a relatively brief period so that everyone who becomes ill does so within one incubation period • Exposure of susceptible population at the same time (1 incubation period) to common source of pathogen. • Exposure is brief (single exposure). • Epidemic curve rises & fall rapidly usually skewed to the right o typically have a steep upslope and a more gradual downslope • Single, brief exposure that did not persist over time • All cases have single incubation period • No person to person spread • E.g. contaminated food or an infected food handler The epidemic curve shown above is from an outbreak of measles that began with a single index case who infected a number of other individuals. (The incubation period for measles averages 10 days with a range of 7-18 days.) One or more of the people infected in the initial wave infected a group of people who become the second wave of infection. So here transmission is person-to-person, rather than from a common source Dr. Mann • MIXED EPIDEMICS • Involve both single common exposure to an infectious agent and secondary propagative spread to other individuals, usually by person to person transmission The figure above is an example of epidemic curve -number of cases during an epidemic were plotted over time. The epi-curve above is an example of epidemic of hepatitis A among patrons of a restaurant who ate green onions, each had a point source of exposure. Dr. Mann • For example, a common-source epidemic of shigellosis occurred among a group of 3,000 women attending a national music festival (Figure 1.24). Many developed symptoms after returning home. Over the next few weeks, several state health departments detected subsequent generations of Shigella cases propagated by person-to-person transmission from festival attendees. • CONTINUOUS COMMON-SOURCE OUTBREAK HERD IMMUNITY IN THE CONTEXT OF COMMUNICABLE DISEASES • Herd immunity o Herd immunity is a term used to describe a situation where enough of a community is immune to an infectious process to prevent person-to-person spread SUPPLEMENT: • may also rise to a peak and then fall, but the cases do not all occur within the span of a single incubation period. This implies that there is an ongoing source of contamination The epidemic curve above is from the cholera outbreak in the Broad Street area of London in 1854 that was investigated by Dr. John Snow. Cholera has an incubation period of 1-3 days, and even though residents began to flee when the outbreak erupted, you can see that this outbreak lasted for more than a single incubation period. This suggests an ongoing source of infection, in this case, the Broad Street pump • Dr. Mann Dr. Mann Black circles show individuals infected by a contagious disease, white circles are individuals who are not affected, and the grey circle represents the one person who was immune. The arrows show the direction of transmission. In A, all individuals were susceptible, and all were affected. In B, only one individual was immune, yet four were protected, even though three of them were susceptible • TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Dr. Mann Page 7 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. EXPLORING OCCURRENCE OF DISEASE • When a disease appears to have occurred at more than an endemic level, and we wish to investigate its occurrence, we ask: o Who was attacked by the disease? (Person) o When did the disease occur? (Time) o Where did the cases arise? (Person) WHO • The characteristics of the human host are clearly related to disease risk. Factors such as sex, age, and race have a major effect PERSON • Age: diseases with different age patterns o Magnitude decreasing with age: disease confers long lasting immunity o Magnitude increasing with age: degenerative diseases o Magnitude high at both extremes of age: reflects low resistance of the young and old o Great exposure during the middle age • Sex: sex differential because of sexual constitution/make up o Greater exposure of males, greater health consciousness of females: early consultation, diagnosis and treatment, more cases recorded • Civil risk factors: o Married at higher risk for cervical CA o Greater family support among the married • Socio-economic status o TB and H. Pylori (low socio-economic status) o Gout –“Disease of kings”, tennis elbow( high socio-economic status) • Ethnic and racial groups – Differences in racial, ethnic, or other group variables may reflect differences in susceptibility or exposure, or differences in other factors that influence the risk of disease • State of Nutrition o Malnourished at higher risk for opportunistic infections o Obese at higher risk for CVS diseases WHEN • Certain diseases occur with a certain periodicity TIME (TEMPORAL VARIATION) Secular Long term fluctuation of disease occurrence (Long)Trend over many decades Increase in # of cases more or less regularly Cyclic Intrinsic every around 5 years due to accumulation of Variation susceptible through births; exhibited by diseases that confer long lasting immunity Fluctuation of disease occurrence during a Seasonal year reflecting climactic changes (Dengue, Variation leptospirosis, influenza) WHERE • Disease is not randomly distributed in time or place PLACE International Related to geographic variation as well as Variation race, ethnicity and culture Results from differences in socio economic National development as well as cultural and Variation geographic differences Related to environmental and access to health differences (Sex linked dystonia Local Variation parkinsonism (XDP), Malaria, Schistosomiasis) CRITERIA FOR INITIATING AN INVESTIGATION • If the disease is a priority • When the disease exceeds the usual expected frequency • Cases are due to common sources • When the disease seems to be more severe • When a disease has not previously occurred for a long time in a place a. Time course by frequency polygon or histogram b. Place: geographical extent of problem c. Person: Population at risk 6. Develop hypothesis 7. Evaluate hypothesis – uses cohort &case-control studies 8. Execute additional studies and refine hypothesis 9. Implement control, and prevention measures (Sanitation, Prophylaxis, Diagnosis and treatment, and Vector Control) 10. Communicate findings 11. Follow up recommendations https://www.cdc.gov/csels/dsepd/ss1978/lesson6/section2.html SUPPLEMENT: ATTACK RATE An attack rate is defined as: !"#$%& () *%+ ,-.%. () - /0.%-.% !"#$%& () 1%&.(* %23(.%/ 0* - 3-&40,"5-& ("4$&%-6 x 100 In this equation, 100 is used as the constant multiplier so the rate can be expressed as a percentage. Dr. Mann • A person who acquires the disease from that exposure (e.g., from a contaminated food) is called a primary case • A person who acquires the disease from exposure to a primary case is called a secondary case. • The secondary attack rate – defined as the attack rate in susceptible people who have been exposed to a primary case SUPPLEMENT: ICEBERG PHENOMENON • The visible part of the iceberg denotes the clinically apparent cases of disease in the community. • The part of the iceberg below the water level denoted the latent, subclinical, undiagnosed and carrier states in the community, which forms the major part. Iceberg Phenomenon, as Illustrated by a Diphtheria Epidemic in Alabama. • Alabama. In epidemics, the number of people with severe forms of the disease (part of iceberg above water as shown here by 2 patients who died and 12 patients with symptoms of clinical illness) may be much smaller than the number of people with mild or asymptomatic clinical disease (part of iceberg below water as shown by the 32 “invisible” cases that would have remained invisible without extensive epidemiologic surveillance). Elmore, Joann G.. Jekel's Epidemiology, Biostatistics and Preventive Medicine EPIDEMIOLOGIC STUDIES DESCRIPTIVE EPIDEMIOLOGY ANALYTICAL EPIDEMIOLOGY INTERVENTION OR EXPERIMENTAL EVALUATION EPIDEMIOLOGY Concerned with disease distribution and frequency Analyze the causes or determinants of disease by testing hypothesis Clinical and community trials about effectiveness of new methods for controlling diseases Measure of the effectiveness of different health services and programs STEPS IN OUTBREAK INVESTIGATION 1. Field work 2. Establish existence of an outbreak 3. Verify diagnosis- uses frequency distributions 4. Define and identify cases 5. Perform descriptive epidemiology; characterize: TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 8 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. TYPES OF EPIDEMIOLOGIC STUDIES DESCRIPTIVE STUDIES ANALYTICAL STUDIES • Describes the distribution • Concerned with of cases by the variables of determining causes of person, time and place in disease occurrence, order to: specifically whether a o Study and explain acute suspected factor is causally outbreaks of disease associated with disease o Follow secular trends of using observational disease occurrence over method of testing time hypothesis or cause o Develop hypothesis of • goes further by analyzing disease transmission relationships between • limited to a description of health status and other the occurrence of a disease variables in a population and is often the first step in an epidemiological investigation • Used if little is known • Purpose is to test the about event or hypothesis because you phenomenon. The purpose already know the is to generate hypothesis relationship of events. TIP: One way of knowing if the question warrants for a descriptive study or analytical study is looking at the construction of the case. If it uses “MAYBE associated” then the use of descriptive study is logical. While if the case presents with words like… “With Significant Relationship or Is related with”. Then, an analytic design is appropriate. Dr. Mann TYPES OF EPIDEMIOLOGIC STUDIES ALTERNATIVE NAME TYPE 1. OBSERVATIONAL DESCRIPTIVE Case Report Case Series Ecological Study Cross-sectional ANALYTICAL Cross-section Case-Control Cohort 2. EXPERIMENTAL Randomized Controlled Trials Field Trials Community Trials UNIT OF OBSERVATION Single patient Group of patients Correlational Prevalence Survey Prevalence Study Case Reference Follow-up Individuals Individuals Individuals Clinical Trials Therapeutic Trials Prophylactic Trial Community Intervention Study Patients Healthy people Communities Modified from Basic epidemiology 2nd edition (WHO) OBSERVATIONAL DESCRIPTIVE EPIDEMIOLOGY DESCRIPTIVE STUDY DESIGNS CASE REPORT “INTERESTING CASE” • Most basic; brief objective report of a clinical characteristic or outcome from a single clinical subject or event. • Highlights the UNAWARENESS of case (ex: adverse drug effect; advanced proliferative diabetic retinopathy) • Methodology: o Identify single noteworthy case o Retrospective data collection o No statistical analysis • Advantages: o Address almost all clinical question or issue; commonly used to report unusual or unexpected events • Disadvantages: o Only few conclusions can be drawn based on evidence o Results are rarely generalizable o Susceptible to bias CASE SERIES • Objective report of a clinical characteristic or outcome from a group of clinical subjects with similar diagnosis, collection of individual case reports which may occur within fairly short period of time • Highlights the SIMILARITIES of case • Methodology: o Identify subjects with regard to clinical events in question o Retrospective or prospective data collection BUT a control group is usually not included o Descriptive statistics are calculated o Results are strengthened when consecutive series of subjects are included over a period of time • Advantage: Easy to conduct and less time and financial use • Disadvantages: o Limited generalizability because of bias, lack of control group o Absence of comparison, not conclusive ECOLOGIC STUDIES (CORRELATIONAL) • The unit of analysis is a group most often defined geographically (urban vs. rural; mountainous region, area with wells as major water source) • Measures that represent characteristics of entire population, used to describe disease in relation to some factors of interest. • Seeks to determine the extent to which two characteristics are related. • Aggregate risk factors CROSS-SECTIONAL SURVEYS (PREVALENCE SURVEYS) • A simple descriptive account of interesting characteristics observed in a group of patients. • Case finding, special surveys to establish incidence or prevalence • Also called prevalence surveys because they focus on a point in time • Exposure and effect at the same time o On a topic or variables of interest which may include the frequency of disease or health disorder, factors associated with health and disease, attributes of positive health. • Advantages: o Relatively simple and rapid; o Can be extended to a case control or cohort study; o Allows the study of the association of a disease with a wide range of factors simultaneously; o Feasible as long as prevalence of condition is high o Convenient for sudden outbreaks • Disadvantages: o Not suitable for rare or acute disease o Factors which may prolong or shorten the duration of the condition may not be seen o Difficult in interpreting temporal sequence of cause and effect o Provides only a snap shot in time. o Selection bias OBSERVATIONAL ANALYTICAL EPIDEMIOLOGY • Common Applications: o Community diagnosis o Investigation of epidemic o Determination of diseases etiology o Evaluations of community interventions and programs • May be observational or experimental: Observational Experimental • Cross-Sectional • Field/Community Trials • Case-Control • Clinical Trials • Cohort ANALYTIC STUDY DESIGNS Ngayon ka pa ba susuko? DOC!!!!! Please basahin mo ito, kapag may tiyaga may linaga! Patience is a virtue, read the whole text please… J) Dr. Mann CROSS-SECTIONAL ANALYTIC (PREVALENCE STUDY) • Examines the relationship between diseases and other variable of interest as they exist in defined population at one particular point in time. • Subject selection at random. • Employs inferential statistics (p value) to determine association or relationship using chi square test. • Uses: o Determine the magnitude of a disease o Hypothesis generation o Evaluation of medical care and health service delivery o Establish baseline data o Studying conditions that are quantitatively measured and that vary over time or relatively frequent diseases that have long duration TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 9 of 77 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. • Advantages: o Conducted quickly o Provides data on a disease rate in a population and descriptive information on other characteristics of the population o Can identify easily stage of disease before it becomes apparent clinically o Less costly than cohort • Disadvantages: o Measures the effect of both incidence and duration; o Cannot identify direction of etiologic association (temporal sequence) o Sensitive to response bias o Observation bias can easily occur since both are measured simultaneously CASE-CONTROL • Persons with a given disease (cases) and persons without the disease (controls) are selected. The proportion of cases and controls of being exposed to a probable risk factor are determined and compared for presence of association. • Starts with the outcome then researcher will be looking for any exposure or factors. OUTCOME → EXPOSURE • Issues: o Selection bias o Observation bias – can be avoided by making the procedures to obtain information as similar as possible or by blinding the investigator o Recall bias o Misclassification – errors in categorization of either exposure or disease status • Example: Comparison of prior estrogen use, in uterine CA patients to that in age-matched controls without CA to assess possible risk of uterine CA SUPPLEMENT THALIDOMIDE A classic example of a case-control study was the discovery of the relationship between thalidomide and limb defects in babies born in the Federal Republic of Germany in 1959 and 1960. The study, done in 1961, compared affected children with normal children. Of 46 mothers whose babies had malformations, 41 had been given thalidomide between the fourth and ninth weeks of pregnancy, whereas none of the 300 control mothers, whose children were normal, had taken the drug during pregnancy. Accurate timing of the drug intake was crucial for determining relevant exposure. What do you call that condition that involves malformations of the arms and legs that is usually associated with thalidomide? Mga besh SAGOT?............. Phocomelia Dr. Mann DESIGN OF A CASE-CONTROL STUDY Basic epidemiology 2nd edition (WHO) COHORT • Exposed and non-exposed populations are identified and followed prospectively over time to determine the rate of a specific clinical disease or event. • Also used in clinical decision analysis to address the predictive value of test positivity or negativity. • Starts with the factors/ exposure then researcher will be looking for outcome • At the time exposure status is defined, all potential subjects must be free from the disease under investigation • Best information about disease causation EXPOSURE → OUTCOME • Done only if there is significant association. • Uses: o Address issues relating to risk factors o Used in clinical decision analysis to assess the differences in test positivity between diseased and non-diseased population • Advantages: o Provide the opportunity to investigate rare diseases as well as those with long period of latency o Less time consuming and less expensive to carry out o Require smaller sample size o Allow for the evaluation of a wide range of potential etiologic exposure o For diseases with long lag • Disadvantages: DESIGN OF A COHORT STUDY o Disease status is measured as a dichotomous categorical variable; Basic epidemiology 2nd edition (WHO o Disease status of the subject is likely to influence ascertainment of exposure factor; o Temporal relationship between exposure and disease may be difficult to establish in some situation; o Has to deal with the problem of selective survival, differential reporting of exposure information between study groups • Types: based on their disease status and differential selection of o Retrospective: all relevant events (both exposure and either the cases or controls on the basis of their exposure outcome of interest) have already occurred when the study is status; initiated. o Information on the potential risk factor and confounders may o Prospective: relevant exposure may or may not have occurred not be available either from records or the subject’s memories at the time the study is begun but the outcome has not yet o Inferential statistics: ODDS RATIO (OR)!!!! occurred • Selection of cases Hospital- based Population-based • Convenient • Avoids bias • Less expensive • More expensive • Prone to selection bias o Incident cases preferable to prevalent o Prevalent cases reflect not only determinants of disease but those of duration as well. • Selection of controls • Uses: o Depends on the characteristics and source of the cases, o Describe the natural history of disease practical and economic considerations o Identify the number of new cases for planning health care o Disadvantages using controls from the general population: services & determine effectiveness of preventive measures o More costly and time consuming o Determine the etiologic factors associated with the onset of disease o Difficulty in contacting healthy people o Example: The association between low birth weight and maternal o Availability of population smoking during pregnancy can be studied by obtaining smoking o Quality of information may not be the same – general histories from women at the time of prenatal visit and then population may not recall exposures with the same level of subsequently correlating birth weight with smoking histories accuracy as that of cases TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN Page 10 of 77 For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. • Advantages: o Less potential bias in recall & observation o Allows for calculation of incidence rate o Can study the association of one factor and many subsequent effects • Disadvantages: o Requires large sample & long follow-up period o More expensive o Attrition – patients are loss to follow up o Confounders o Controls are difficult to identify o Surveillance bias o No blinding and randomization o Inferential statistics: RELATIVE RISK (RR)!!