Biostatistics and Epidemiology PDF

o Far Eastern University - Dr. Nicanor Reyes Medical Foundation To diagnose the health of a community and ○ Employment and working conditions: proposing appropriate, practical, and acceptable people in employm...

o Far Eastern University - Dr. Nicanor Reyes Medical Foundation To diagnose the health of a community and ○ Employment and working conditions: proposing appropriate, practical, and acceptable people in employment are healthier when public health interventions to control and prevent they have more control over their working disease in the community. condition. Eg: The interventions made by WHO, DOH, etc Eg: job security, clean for the COVID pandemic (vaccines) to prevent its environment occurrence and proliferation, as well as patient Immunologic: immunity (natural and acquired). death. Nutritional: proper and balanced diet. Genetics: inheritance plays a part in determining lifespan, healthiness, and the likelihood of DETERMINANTS OF HEALTH: BEINGS MODELS developing certain illnesses. ○ Genetic screening: done on newborns in EXTRA NOTES (FROM LECTURE) order to determine if they have certain Determinants: Any factors, events or illnesses (eg: diabetes). characteristics that can change health Services, social, and spiritual: conditions. ○ Services: access and use of services that BEINGS Model: can prevent and treat diseases that can ○ B - Behavioral influence health. ○ E - Environment ○ Social support network: number of ○ I - Immunologic / Immunity support networks (eg: family, ○ N - Nutrition / Nutritional community, peers). ○ G - Genetics Income and social status: ○ S - Services higher income and social status are linked to better health. This can cause a gap between the Gender: men and women suffer from different richest and poorest people when types of diseases at different ages. it comes to health. Individual behavior and lifestyle: Spiritual: includes customs and traditions, as ○ Intrinsic factors: ability and motivation well belief of the support networks. This affects to engage in healthcare (taking the health of individuals (eg: family members medication) and access to technology. practice meditation which will lead to better ○ Extrinsic factors: behavior (eg: health). healthcare - ability to schedule appointments). CHAPTER 6: INTRODUCTION TO EPIDEMIOLOGY Attitude and perceived skills of the healthcare providers (patient care - whether patients are EPIDEMIOLOGY satisfied). The study of a scientific method of problem Physical or sedentary life. solving that helps "disease detectives" understand Eg: The Framingham study how people get sick and die, who gets sick and established links between dies, and how to avoid getting sick. smoking, lack of physical activity Although it was originally focused on the study of and cardiovascular disease. infectious disease, the scope has expanded to Education: low education levels are linked with include chronic disease and health related poor health, more stress and lower conditions. self-confidence. INFECTIOUS DISEASE Environment: comprises safe water, clean air, Refers to a contagious or transmissible disease. healthy workplace, safe houses, communities and CHRONIC DISEASE roads all contribute to good health. Refers to a disease that is long lasting. JULIA ANDREA BLEZA o Far Eastern University - Dr. Nicanor Reyes Medical Foundation HEALTH-RELATED STATES OR CONDITIONS ENVIRONMENTAL Diseases or events that cause illness, deaths, or Studies the effect of the environment on human disability. health; can subspecialize in water quality, air Examples are heart attacks or car accidents that pollution, chemical exposures, radiation, and can cause death, illness, or disability. others. Conditions that may not cause death, but are very FORENSIC important because they cause disability include Studies the joint integration of law enforcement autism or arthritis. functions and public health in criminal contexts DISTRIBUTION (e.g., bioterrorism). Refers to time, place and types of persons affected GENETIC by a particular disease or condition Studies the role of genetics in disease (demographics). development; can include infectious or chronic diseases. INFECTIOUS DISEASE USES OF EPIDEMIOLOGY Studies diseases that are acute and contagious; can include long-lasting diseases that are Epidemiology is also used to describe the extent of transmissible. disease in a population and the natural history INJURY and characteristics of a disease, as well as to Studies the distribution and risk factors for evaluate preventive measures and guide policy injuries, either accidental or intentional decisions. PERINATAL Epidemiology methods can also establish risk Studies health problems of newborns. factors. Some risk factors are non-modifiable, REPRODUCTIVE HEALTH whereas others are modifiable. Studies normal reproductive processes and problems that can occur, including infertility, NATURAL HISTORY birth defects, and low birth weight. The course of a disease if left untreated. SOCIAL EPIDEMIOLOGY RISK FACTORS Studies the effect of community socioeconomic Characteristics associated with disease factors on health. development. VIOLENCE NONMODIFIABLE RISK FACTORS Studies the effect of violence on health. Risk factors that cannot be changed or eradicated. Eg: age, sex, etc. TERMINOLOGIES MODIFIABLE RISK FACTORS Risk factors that can be changed or eradicated with lifestyle changes. ETIOLOGY Eg: quitting to smoke Biological cause of a problem or disease. AGENT Capable of causing an illness. SPECIALTIES IN EPIDEMIOLOGY NULL HYPOTHESIS A hypothesis that is stated as if there is no CHRONIC DISEASE relationship between the study factors and the Studies the occurrence and risk factors for disease disease. such as cancer, heart disease, and diabetes that EPIDEMIC THRESHOLD are slow to develop but span many years. Upper end of the normal pandemic level of BEHAVIORAL infections. Studies lifestyle factors that may be associated HUMAN SUBJECT with disease status; examples include smoking, Any person that is observed for purposes of lack of physical activity, poor diet. research. JULIA ANDREA BLEZA o Far Eastern University - Dr. Nicanor Reyes Medical Foundation A graphic demonstration of the relationship between the agent, environment and individual as CHAPTER 7: FUNDAMENTALS OF EPIDEMIOLOGY a function of time. Composed of three parts: + Note: Concepts that are also included in lesson 2 ○ Agent: what causes the disease. are still included here (except for the sensitivity ○ Host: personal characteristics of those and specificity). affected by the disease. ○ Environment: external factors that TERMINOLOGIES cause or allow the disease to spread. Time is another important part that ties into the elements of the triangle and is crucial in CAUSALITY understanding disease transmission. Refers to determining the cause of a disease. MODERN EPIDEMIOLOGIC TRIANGLE SCREENING TEST Modified version of the traditional epidemiology Test given to people who have no symptoms to triangle to reflect the different characteristics of check for the presence of a particular disease. non-infectious disease diseases. The time element is still present, but the modern NATURAL HISTORY OF DISEASE epidemiology triangle includes groups of: ○ Populations (instead of person) ○ Causative factors (instead of LATENCY PERIOD environment) The time from the start of a disease process until ○ Risk factors (instead of agent) signs and symptoms appear. INCUBATION PERIOD The time between infection and clinical disease. CLINICAL The stage of disease when signs and symptoms appear. NONCLINICAL The stage of disease when clinical signs and symptoms are not present. PRECLINICAL Non-clinical disease because signs and symptoms are not yet present. SUBCLINICAL Non-clinical disease because signs and symptoms will not become apparent. MORBIDITY Any departure from the state of physiological or psychological well. DISEASE OCCURRENCE MORTALITY Resulting in death. DESCRIPTIVE EPIDEMIOLOGY The pattern of disease occurrence from the EPIDEMIOLOGIC TRIANGLE perspectives of person, place and time. OUTCOME Refers to a particular disease under study. EPIDEMIOLOGIC TRIANGLE DEPENDENT VARIABLE Something that we are studying, usually called an outcome. JULIA ANDREA BLEZA o Far Eastern University - Dr. Nicanor Reyes Medical Foundation EXPOSURE 3. The pathogen from the pure culture should cause Also known as a risk factor or an independent the disease when inoculated into a healthy, variable. susceptible laboratory animal. INDEPENDENT VARIABLE 4. The pathogen must be reisolated from the new Risk factors are exposures that we think might host and shown to be the same as the originally affect the outcome. inoculated pathogen. PERSON BRADFORD HILL In epidemiological studies are often referred to as To help epidemiologists sort through many the study population or the group of individuals scientific studies, some of which are contradictory, being studied. Sir Austin Bradford Hill, a British medical PLACE statistician, developed a list of elements to Generally meant to imply the geographical consider: location. ○ Temporal relationship: exposure TIME (agent or risk factor) always precedes the This could apply to seasonal patterns or it could outcome. refer to trends over time. ○ Strength: this is defined by the size of the association as measured by appropriate statistical tests. CAUSALITY ○ Dose-Response relationship: an increasing amount of exposure increases CAUSE the risk. Something that brings about an effect or a result. ○ Consistency: the association is DIRECT CAUSE consistent when results are repeated in Refers to a factor that causes a problem without studies in different settings, using any intermediate steps. different methods. INDIRECT CAUSE ○ Plausibility: findings agree with Refers to a factor that may cause a problem, but currently accepted understanding of through an intermediate step. pathological processes. ○ Consideration of alternate KOCH’S POSTULATES explanations: in judging whether a Four rules that established the coastal relationship reported finding is causal, it is always between an infectious agent and a particular necessary to consider multiple hypotheses infection. before making conclusions about the Basically if (1) an organism can be isolated from a causal relationship between any two items host suffering from the disease, and (2) the under investigation. organism can be cultured in a laboratory, and (3) ○ Experiment: the condition can be the organism causes the same disease when altered (prevented or ameliorated) by an introduced to into another host, and (4) The appropriate experimental regimen. organism can be re-isolated from that host - then, ○ Specificity: this is established when a the organism is the cause of the disease and the single putative cause produces a specific disease is an infectious disease. effect. ○ Coherence: the association should be KOCH’S CRITERIA compatible with existing theory and 1. The microorganism or other pathogen must be knowledge. present in all cases of 2. The pathogen can be isolated from the diseased LEVELS OF PREVENTION host and grown in pure culture. LEVELS OF PREVENTION JULIA ANDREA BLEZA o Far Eastern University - Dr. Nicanor Reyes Medical Foundation Refers to three types of prevention: primary Proportion of clinically apparent cases that are secondary, and tertiary. severe or fatal. PRIMARY PREVENTION CARRIERS Avoid the initial occurrence of a disease. Persons who are infectious but have subclinical SECONDARY PREVENTION disease. Limits the effect of a disease by early detection and treatment. NATURAL HISTORY OF DISEASE TERTIARY PREVENTION Reduces the impact of a disease that has already developed by preventing complications. NATURAL HISTORY OF DISEASE Process wherein individual disease developments over time in the absence of treatment (according SCREENING TESTS to the Center for Disease Control / CDC): Primary intervention: ○ Susceptible Secondary intervention: ○ Nonclinical disease Tertiary intervention: ○ Clinical disease ○ Recovery, disability or death EXTRA NOTES (FROM LECTURE) Stage 1: Stage of Susceptibility ○ No disease developed yet. ○ Susceptible hose is exposed or comes into close contact with an agent. LESSON 2: DISEASE CAUSATION, OCCURRENCE Stage 2: Stage of Subclinical Disease AND EXPOSURE ○ Asymptomatic initially. ○ Once the disease is activated, pathological changes can occur NATURAL HISTORY OF DISEASE: KEY TERM without the host’s knowledge. ○ The causative agent may enter or ETIOLOGY already entered the body, and can Cause or origin of a disease multiply. INCUBATION PERIOD In between Subclinical and Clinical: Onset of Time from the exposure to an infectious agent Symptoms until signs and symptoms appear. ○ Incubation period: time interval INFECTION between the initial exposure to the Infectious agent is present on or within the host agent and the onset of symptoms from and is capable of surviving and replicating the unknown disease. INFECTIVITY ○ Usual time of diagnosis: A screening Proportion of exposed persons who become test can be done to determine the infected. presence of the disease. PATHOGENICITY Stage 3: Stage of Clinical Disease Proportion of infected individuals who develop ○ Patient is symptomatic. clinically apparent disease. ○ Disease is advanced. VIRULENCE JULIA ANDREA BLEZA