Health Statistics and Epidemiology PDF

Health Statistics and Epidemiology Ma. Veronica C. Legaspi, RN, MPH Demography Science which deals with the study of population sizes, composition and distribution in space. Population Refers to the number of people in a given place or areas in a given time.  Household Is a person or...

Health Statistics and Epidemiology Ma. Veronica C. Legaspi, RN, MPH Demography Science which deals with the study of population sizes, composition and distribution in space. Population Refers to the number of people in a given place or areas in a given time.  Household Is a person or group of related or unrelated persons who live together in the same dwelling unit, who acknowledge one adult male or female as the head of the household, who share the same housekeeping arrangements and who are considered a single unit  Sources of Demographic Information 1.Census- an official and periodic enumeration of population Two ways of assigning people during Census: De jure – when people are assigned to the place where they usually live regardless of where they are at the time of the census De facto – people usually present during time of the census regardless of their usual place of residence. 2. Sample surveys 3. Registration Population Size? Information on population changes Prioritize & strategize health programs or interventions for the community Assess possible health related factors  2 methods of measuring population changes 1.Comparing the CBR and CDR 2.Comparison by Census Birth Rate Average number of live births in a year for every 1000 people in a total population. Philippines 22.28 Japan 6.95 United States 12.28 Canada 10.17 Somalia 37.98 Death Rate Average number of deaths in a year for every 1000 people in a total population. Philippines 6.41 Japan 11.59 United States 8.38 Canada 8.12 Somalia 11.62 Natural Increase Difference between the number of births and the number of Deaths occurring in a population in a specific period of time. NI = Births - Deaths (Specified Year) (Specified Year) (Specified Year)  Philippines CBR= 22.28 CDR= 6.41  Crude Birth Rate Ex. Compute for Crude Birth Rate In Kidapawan City, North Cotabato, there were 4567 births. The total population was 125,447. The CBR is  Crude Birth Rate Ex. Compute for Crude Birth Rate In Kidapawan City, North Cotabato, there were 4567 births. The total population was 125,447. The CBR is 36.4 per 1000 population  Crude Death Rate Ex. Compute the Crude Death Rate In the municipality of Balo-i, Lanao Del Norte, there were 5634 deaths. The total population was 192,310. The CDR is  Crude Death Rate Ex. Compute the Crude Death Rate In the municipality of Balo-i, Lanao Del Norte, there were 5634 deaths. The total population was 192,310. The CDR is 29.3 per 1000 population Rate of Natural Increase Difference Between the Crude Birth Rate (CBR) and Crude Death Rate (CDR) in a specific period of time. NRI= CBR- CDR Calculate the Rate of Natural Increase Leyte South Biliran Samar Eastern North Leyte Samar Samar Population 1,742,679 421,750 171,612 780,481 467,160 632,379 Deaths 12,345 8,034 5,489 7,609 4,679 5,543 Births 15,745 15,023 3,456 11,234 6,987 12,342 RNI Calculate the Rate of Natural Increase Leyte South Biliran Samar Eastern North Leyte Samar Samar Population 1,742,679 421,750 171,612 780,481 467,160 632,379 Deaths 12,345 8,034 5,489 7,609 4,679 5,543 Births 15,745 15,023 3,456 11,234 6,987 12,342 RNI 2.0 16.6 -11.8 4.6 4.9 10.8 Demographic indicators Population Statistics Sex ratio Dependency ratio Density Population size Vital Statistics BR (Birth Rate) DR (Death Rate) Population Composition Sex Composition Age Composition Age and Sex Composition  Sex Ratio Number of females to the number of males in the population. Number of female per 1000 male population Number of Females Number of Males X 1000 Calculate Sex Ratio Males 1,996,355 Females 1,930,234 Calculate Sex Ratio Males 1,996,355 Females 1,930,234 967 Females per 1000 Males  Age Composition Median = arrange age from smallest to the highest, divide population into 2 equal equal parts & identify number in between Ex. you are trying to decide an activity for a suitable for the majority group of people. Age of the group are as follows. 12, 8, 13, 65, 10, 10, 9 Median Mean/Average 8 8+9+10+10+12+13+65 9 =127 10 7 10 18 Years old 12 13 65 Age and Sex Composition  Population Distribution Urban Rural Distribution = illustrates the proportion of the people living urban and rural areas Crowding Index = describes the ease by which a communicable disease will be transmitted from one host to another. Divide number of persons in a house hold to the number of rooms Population Density = will determine how congested a place is and has implications in terms of adequacy of basic health services. It describes how crowded a place is.  Vital Health Statistics Nurse Function Collects data Tabulates data Analyses data and interprets data Evaluates data Recommends redirection and /or strengthening of specific areas of health program  Rates and Ratio RATE = shows the relationship bet. a vital event and those persons exposed to the occurrence to the said event with in a given area and specific period of time RATIO = describe relationship between 2 numerical quantities or measures of events without taking particular considerations to the time or place. CRUDE or GENERAL RATES = rates are referred to the total living population. SPECIFIC RATE = the relationship is for a specific population class or group.  Vital Statistics Refers to the systematic study of vital events such as births, illness, marriages, divorces/separations and deaths. Uses of Vital Statistics Planning human development Dynamics of reproduction Life-tables Risks of dying Population growth dynamics Population projections Monitoring & evaluating interventions  Can facilitate information for Provision of services for vulnerable populations (i.e. single mothers & children) Regional & urban/rural comparisons Allocation of resources (i.e. health care, education, & social security) Crude Birth Rate =Natural growth and increase of Population. CBR = # OF Registered livebirth in a year x 1000 estimated population in the same year Crude Death Rate =mortality from all causes of Population CDR = # OF Registered deaths in a year x 1000 estimated population in the same year Infant Mortality Rate =risk of dying during the first year of life IMR = # OF number of deaths in the first year of life in a year x 1000 Total number of livebirths registered in the same year Maternal Mortality Rate=measures the risk o dying for causes related to pregnancy, childbirth and puerperium. MMR =# number of deaths from maternal causes registered given year Total number of livebirths registered in the same year x 1000 Fetal Death Rate = measures pregnancy wastage. Death of the product of conception occurs prior to its complete expulsion, irrespective of duration of pregnancy FDR = # fetal deaths registered in a given calendar year x 1000 Total Number of Live births registered in a same year Neonatal Death Rate= risk of dying the 1st month of life. NDR = # of deaths under 28 days of age registered x 1000 number of livebirths reg. in the same year ATTACK RATE Measures the risk of exposure. Useful in epidemiological investigation AR = number of person acquiring the disease x 100 number of exposed to the same disease in same year sCENARIO sCENARIO 63.0 58.6 60.5 62.5 62.2 62.2 64.3 59.6 69.6 57.7 56.8 65.8 79.6 14.3 53.2 74.1 Attack Ratio Case Fatality Rate Killing power of the disease No. of registered Deaths from a specific disease CFR = for a given year x 100 No. of registered cases from specific disease in same year Incidence and Prevalence INCIDENCE RATE = Measures the frequency of occurrence of the phenomenon during a given period of time. Deals only with New Cases No. of New Cases of particular disease Registered during a specific period of time IR = Population at risk of developing the disease x 100 (F) Incidence and Prevalence PREVALENCE RATE = Measures the proportion of the population which exhibits a particular disease at a particular time. No. of New and old cases of a certain disease registered at a given time PR = Number of persons examined at same time x 100 (F) iNTRODUCTION TO bASIC ePIDEMIOLOGY  Learning Objectives Define Epidemiology. Define Field Epidemiology. Identify the different core epidemiology functions. Describe primary applications of epidemiology in public health practice. Describe epidemiology as to Time, Place and Person.  Epidemiology originated from the Greek words “epi”- meaning on or upon, “demos” meaning people and “ logos” meaning study of.  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. Study scientific discipline data driven and relies on systematic approach basic science of public health provide foundation for practical and appropriate public health action basis for causal reasoning in public health Distribution frequency pattern Determinants Factors that influence disease or health events assumption: Disease does not occur RANDOMLY analytic epidemiology provide “why” and “how” to provide evidence to direct, prompt and effective Application applying the knowledge gained by the studies to community-based practice An outbreak, needs epidemiologic judgment of local conditions  Objectives of Epidemiology To identify the etiology or the cause of the disease and the risk factors. To determine extent of disease found in the community. To study the natural history and prognosis of disease. To evaluate existing and new preventive and therapeutic measures and modes of health care delivery. To provide foundation for developing public policy and regulatory decisions relating to environmental problems.  Uses of Epidemiology Study the health History of the population Assessing the community’s health Relevant sources of data: What are actual and potential health problems? Where are they occurring? Which populations are at risk? Which problems are increasing or decreasing over time? How do these patterns relate to public health services available? Diagnose the Community and the condition of the people Assess evaluate the effectivity of health services  Uses of Epidemiology Completing a clinical picture Epidemiologists rely on clinicians and laboratorians for proper diagnosis but also contribute to physicians’ understanding of clinical picture and natural history of disease Core Epidemiology Function 1. Public Health Surveillance 2. Field Investigation 3. Analytic Studies 4. Evaluation 5. Linkages 6. Policy Development 1. Public Health Surveillance refers to the ongoing, systematic collection, analysis, interpretation and timely dissemination of health data for the planning, implementation and evaluation of public health program. The use of information based from these data to disease prevention and health promotion program completes the surveillance cycle in public health. “The essence of public health surveillance is the use of data to monitor health problems to facilitate their prevention or control 1. Public Health Surveillance 2. Field Investigation A phone call to confirm or clarify circumstances of reported case Coordinated efforts of people to characterize extent of an epidemic or identify cause Objectives for investigations may vary 3. Analytic Studies Rigorous methods than surveillance and outbreak investigation Hallmark of analytic study is use of a comparison group  4. Evaluation process of determining, as systematically and objectively as possible, the relevance, effectiveness, efficiency, and impact of activities with respect to established goals. Effectiveness refers to the ability of a program to produce the intended or expected results in the field; effectiveness differs from efficacy, which is the ability to produce results under ideal conditions. Efficiency refers to the ability of the program to produce the intended results with a minimum expenditure of time and resources.  5. Linkages During an investigation an epidemiologist usually participates as either a member or the leader of a multidisciplinary team. Other team members may be laboratorians, sanitarians, infection control personnel, nurses or other clinical staff, and, computer information specialists 6. Policy Development Public health workers regularly provide input, testimony, and recommendations regarding disease control strategies, reportable disease regulations, and health-care policy. Descriptive Epidemiology Descriptive epidemiology characterizes as to time, place, person through comprehensive characterization. It identifies population at risk for the disease and provide clues about etiology, source and modes of transmission. This will be used to begin intervention and prevention measures. The W’s of descriptive Epidemiology: What: Health issue of concern Who: Person Where: Place When: Time Epidemic Curve Variability in disease occurrence can also be analyzed from different points of view. These observations are organized and illustrated as an Epidemic Curve.  Place Disease pattern by place can be analyzed by place-related difference based on geographic localities or characteristics common in a locality. Examples are urbanicity, economic development and climate type. Early clues about many diseases have come from comparing geographic-specific mortality rates. Place Person  Person Variation in disease rates by person variables suggests differences in the opportunity for exposure to the agent or differences in their susceptibility once exposed. This element pertains to personal characteristics which may affect illness. Concepts of Public Health Surveillance Surveillance Surveillance came from “sur” meaning over and “veller” meaning to watch. “close and continuous observation of one or more persons for the purpose of direction, supervision, or control Continued watchfulness over the distribution and trends of incidence [of a disease] through the systematic collection, consolidation, and evaluation of morbidity and mortality reports and other relevant data.” – by Alexander Langmuir, 1963 General application of surveillance to public health problems Roles of a Nurse in Surveillance 1. Identify, define and measure the health problem of interest 2. Collect and compile data about the problem 3. Analyze and interpret these data 4. Provide these data and their interpretation stakeholders/ program managers 5. Monitor and periodically evaluate the usefulness and quality of surveillance Core process of public health surveillance Core process of public health surveillance Core process of public health surveillance  Identifying and Selecting a Health Problem for Surveillance a. Public health importance – Incidence, prevalence, severity, disabilities, mortality, socioeconomic impact, community, outbreak potential, Ability to prevent, control, or treat Capacity of health systems Speed and response, economics, availability of response, National Surveillance System National Surveillance System National Surveillance System National Surveillance System Nurse Function in Epidemiology Maintains surveillance of the occurrence of notifiable disease Coordinates with other members of the health team during outbreaks Participates in case finding and collection of laboratory specimen. Isolates cases or communicable diseases Nursing care teaching & supervises care Nurse Function in Epidemiology Teaches household concurrent and terminate disinfection Follow up cases and contacts Education campaign Referral of cases Coordinates with other concerned community agencies Accomplishes reports and keeps records submits it to proper office. Epidemiological investigation Outbreak or an Epidemic is the occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time. EPIDEMIC to situations involving larger numbers of people over a wide geographic area. OUTBREAK as an epidemic limited to localized increase in the incidence of disease, e.g., village, town, or closed institution.  SPORADIC refers to a disease that occurs infrequently and irregularly. ENDEMIC refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area. CLUSTERING is an aggregation of cases in a given area over a particular period without regard to whether the number of cases is more than expected. Even if the current number of reported cases exceeds the expected number, the excess may not necessarily indicate an outbreak Increase in cases may be due to the following: changes in local reporting procedures changes in the case definition increased interest because of local or national awareness, improvements in diagnostic procedures A new physician, infection control nurse, or healthcare facility may more consistently report cases result of misdiagnosis or laboratory error sudden changes in population size  Outline of Plan for Epidemiological Investigation 1.Establish fact of presence of Epidemic Verify Diagnosis a. Is the disease that which it is reported to be? b. Are all the cases due to the same disease Reporting a. Is it reasonably complete? b. Is the data accurate Unusual prevalence of the disease a. Past experience of the disease b. Relation to nature of the disease Outline of Plan for Epidemiological Investigation 2. Establish time and space relationship of the disease Are cases limited or concentrated by place Relationship by onset of time 3. Relations to characteristic of the group community Relation of case by person (age, sex, occupation etc.) Relation to vital health facilities Relation to food and water Relation to other cases 4. Correlation of all data obtained Build final case and conclusion Provision of control measures STEPS IN OUTBREAK INVESTIGATION 1.Prepare for field work 2.Establish the existence of an outbreak 3.Verify the diagnosis 4.Construct a working case definition 5.Find cases systematically and record information 6.Perform descriptive epidemiology 7.Develop hypotheses 8.Evaluate hypotheses epidemiologically 9.As necessary, reconsider, refine, and re-evaluate hypotheses 10.Compare and reconcile with laboratory and/or environmental studies 11.Implement control and prevention measures 12.Initiate or maintain surveillance 13.Communicate finding  Epidemiological Triad A model that describes the causation of a disease Agent Host Environment Agent Infectious microorganism or pathogen: a virus, bacterium, parasite, or other microbe. Bacteria- Tuberculosis, Salmonellosis, Stryptococcal infections Viruses - Ex. Viral hepatitis A, influenza, viral meningitis Mycoses- diseases caused by fungi (Ex. Ringworm, athlete’s foot, candidiasis) Protozoa- Malaria, Amoebiasis Helminths- Schistosomiasis Characteristics of Infectious Disease Agents: INFECTIVITY - capacity of the agent to enter and multiply in a susceptible host to produce infection or disease. Poliomyelitis and measles are diseases with high infectivity. PATHOGENICITY- capacity of the agent to cause disease in the infected host VIRULENCE- refers to the severity of the disease TOXIGENICITY- capacity of the agent to produce toxin or poison RESISTANCE- ability of the agent to survive adverse environmental conditions ANTIGENICITY- ability of the agent to induce antibody production in the host. Host refers to the human who can get the disease. Example of host factors are: age, race, sex, socioeconomic status, and behaviors (smoking, drug abuse, lifestyle, sexual practices and contraception, eating habits), genetic composition, nutritional and immunologic status, anatomic structure, presence of disease or medications, and psychological makeup are some of the host factors which affect a person’s susceptibility and response to an agent.  Environment refers to the extrinsic factors that affect the agent and the opportunity for exposure. Environmental factors include physical factors such as geology and climate, biologic factors such as insects that transmit the agent, and socioeconomic factors such as crowding, sanitation, and the availability of health services. Thank you! www.reallygreatsite.com Resource Page