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level: EPIDEMIOLOGIC MEASURES

Questions and Answers List

level questions: EPIDEMIOLOGIC MEASURES

Question	Answer
Basic Measurement	o Rate, Ratio and Proportion o Prevalence Rate o Incidence rate o Case fatality rate o Mortality rates(age specific/cause specific) o Attack rate O Other measures
EPIDEMIOLOGIC MEASURES	1 RATE 2 RATIO 3 PROPORTION
 comprises a numerator, denominator, time specification & multiplier.  The time dimension is usually a calendar year.  Rate is expressed per 1000, 10,000 or 100,000 selected according to convenience to avoid fractions  used to estimate probability or risk of occurrence of a disease or to assess the accessibility or coverage of healthcare system.	RATE Rate = No. events in spec. period / population at risk in spec. period x K
 A fraction in which the numerator is not part of the denominator. Ex: Fetal death ratio: Total no. of fetal deaths/total no. of live births  Fetal deaths are not part of live births Other ex: doctor-population ratio, child-woman ratio	RATIO
 Specific type of ratio in which numerator is included in the denominator and the resultant value is expressed as % age.	PROPORTION
MEASUREMENTS OF MORBIDITY	1 Incidence 2 Prevalence
1 No. of newly added disease cases in a population at risk during a specified time interval. Number of new cases of a disease which come into being during a specified period of time. 2 Measure of instantaneous rate of disease; useful in estimating length of time needed to follow up individuals	1 Incidence 2 Rate
1 The proportion of individuals in a population who have disease at a specific point in time Number of current/existing case (old and new) of a specified disease at a point of time It help to estimate the burden of disease Identify potentially high-risk populations. They are essentially helpful to plan rehabilitation facilities, manpower needs, etc. (Number of current case of a specified disease at a point of time)/(estimated population at the same point of time) x 100 2 Measure the individual risk of disease; Useful in estimating the probability that an individual will be at ill at specific point in time	1 Prevalence 2 Ratio
Prevalence two types:	1 Point P (day, week, month) 2 Period P Point P is the commonly used term
is the number of all current cases (old & new) of a disease at one point in time in relation to a defined population. The “point” in this may consist of a day, several days or even a few weeks depending upon the time it takes to examine the population sample.	POINT PREVALENCE
Is the proportion of a population that has the characteristic or disease at any point during a given time period of interest. “Past 12 months” is a commonly used timeframe. It includes cases arising before but extending into or through to the year as well as those cases arising during the year	PERIOD PREVALENCE
RELATIONSHIP BETWEEN INCIDENCE AND PREVALENCE	Prevalence =Incidence x Duration
Useful for comparing the risk of disease in groups with different exposures. can be specific for a given exposure. no. of people at risk in whom a certain illness develops total no. of people at risk	ATTACK RATE (AR)
MEASUREMENTS OF MORTALITY	1 CASE FATALITY RATE 2 PROPORTIONAL MORTALITY RATE OTHER MEASURES 1 Maternal mortality ratio (MMR) 2 Crude birth rate 3 Under-five mortality rate 4 Infant mortality rate
→ Measure of the severity of a disease which defined as the proportion of cases of a specified disease or condition which are fatal within a specified time	CASE FATALITY RATE
→ It is sometimes useful to know what proportion of total deaths are due to a particular cause (e.g., cancer) or what proportion of deaths are occurring in a particular age group (e.g., above the age of 50 years). → It expresses the " # of deaths due to a particular cause (or in a specific age gp.) per 100 (or 1000) total deaths."	PROPORTIONAL MORTALITY RATE
1 The number of women who die as a result of pregnancy and childbirth complications per 100,000 live births in a given year. 2 Annual number of births per 1,000 population.	1 Maternal mortality ratio (MMR) 2 Crude birth rate
1 Probability of dying between birth and exactly five years of age expressed per 1,000 live births 2 Probability of dying between birth and exactly one year of age expressed per 1,000 live births.	1 Under-five mortality rate 2 Infant mortality rate