Epidemiological approach
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This document summarizes key concepts in epidemiological studies. It discusses how epidemiological studies aim to determine the differences between those who get a disease and those who are spared. This is done by investigating the nature and extent of the disease, causative agents, sources of infection, modes of transmission and susceptibility of the population. The document also outlines the two main approaches in epidemiological investigations - asking questions and making comparisons. It provides examples of the types of questions asked and comparisons that can be made, such as between rural and urban populations. Finally, it defines epidemiological terms like case counts, rates, ratios and proportions that are used to measure and compare health outcomes.
Epidemiological approach
- 1. GOOD EVENING PRESENTED BY, MRS. B.kalPaNa, M.SC (N) aSSo. PRoFESSoR DEPT oF CoMMUNITY HEalTH NURSING SREE NaRaYaNa NURSING CollEGE NElloRE
- 2. Why? Epidemiological studies are based on sick and well people to determine the crucial difference between those who get disease and those who are spared…………….
- 3. An epidemiological studies are aimed to find……………. Nature and extent of the disease Causative agent Sources of infection Period of communicability Mode of transmission Susceptibility of population Incubation period Method of prevention and control
- 4. “ The epidemiological investigation to health problems involves the two basic approaches” Epidemiological approach
- 5. a. Asking questions b. Making comparisons
- 6. a. Asking Questions The key information can be approached through a series of questions Related to health events What are the actual and potential health problems its manifestations and characteristics?
- 7. Who are affected, with reference to age, sex, social class………? Where are they occur in terms of place? Which populations are increased at risk? When does it happen in terms of day, month, season etc……….?
- 8. Why does it happen in terms of contributing or causative factors? Which problems have declined? Which problems are increasing or have the risk to increase?
- 9. Related to health action What can be done to reduce the problem and its consequences? How can it be prevented in the future? What action should be taken by the community to prevent and manage the problem?
- 10. Action taken by the health services? Action taken by other sectors? Where and for whom these activities carried out? What resources are required in future? How are the activities to be organized? What difficulties may arise, and how it has to overcome?
- 11. b. Making Comparisons This approach is to make comparisons and draw inferences. Comparison may be made between different population at a given time eg. Rural with urban population between sub group of population eg. Male with female population between various periods of observation eg. Different seasons
- 12. • Case Counts • Rates • Ratios • Proportions Tools of Measurement
- 13. Case Counts The case count refers to the number of cases of a disease or other health phenomenon being studied eg Number of cases of Still births It Can be useful for allocation of health resources
- 14. Rate The rate measures the occurrence of some particular event ( development of disease or the occurrence of death) in a population during a given period of time. Expressed as: Example: Death rate: n y x 10× 1000 yearsameofpopulationyear-Mid yearoneindeathsofNumber ×
- 15. A rate comprises the following elements- Numerator, denominator, time specification and multiplier. The time specification is usually a calendar year The rate is expressed per 1000 or some other round figure like 100,000.
- 16. Various categories of rates 1. Crude rate: These are actual observation rates. Eg: Birth rate, Death rate Crude rates are un standardized rates 2. Specific rate: These are the actual observed rates due to specific causes (tuberculosis) occurring in specific groups (age-sex) during specific time period (annual, monthly, weekly)
- 17. 3. Standardized rates: These are obtained by direct or indirect method of standardization Eg: age and sex standardized rates
- 18. Ratio The ratio is the most fundamental measurement in epidemiology using two variables X and Y Obtained by dividing one quantity by another with out implying any specific relationship between numerator and denominator Expressed as: yx or y x ;
- 19. The number of children with scabies at a certain time The number of children with malnutrition at a certain time Other examples: Sex-ratio, Doctor-population ratio, Child-woman ratio
- 20. Proportion The proportion is a ratio where the numerator is included in the denominator Usually proportions are expressed as a percentage Proportion is the part of the whole Expressed as 100 timesameinchildrenofnumberTotal timeaatScabiesofNumberThe ×
- 21. Numerator: It refers to the number of times an event has occurred in a population during specified time period. It is a component of denominator Denominator: It may be related to the population or related to the total event Related to population: Mid year population Related to total events: Number of accidents for 1000 vehicles
- 22. OUR ROLE • Screening • Notification • Evaluation of Health Services • Management • Prevention and control
- 23. References ActivEpi CD-ROM; Kleinbaum ActivEpi Companion Textbook; Kleinbaum, Sullivan, Barker Epidemiology in Medicine, Hennekens
- 24. THANK U…