Question

In 1960, investigator A took a simple random sample of 1,050 adults from an urban community of 100,000 (.i.e. each adult had 1050/100,000 chance of being chosen for the sample). After examining the entire study population of 1050, she detected 50 cases of disease Q, a chronic disease for which there is no recovery or cure. In 1965 (5 years later), investigator A re-examined all of the survivors from her original study population and determined the cause of death in those who had died since the first examination. Of the 50 subjects in whom disease Q was was detected in 1960, 40 died prior to being re-examined in 1965. Of those who did not have disease Q, 100 subjects developed it between 1960 and 1965 including 50 subjects who died prior to reexamination prior to reexamination (presumably due to disease Q). Among the subjects who did not contract disease Q, 15% had died between the 1960 and 1965 examinations.

1- Calculate prevalence of disease Q among adults in the community at the initial examination.

2- 5 year cumulative incidence of disease Q (make no adjustment for deaths from other causes other than disease Q). What is the impact on this measure of deaths among individuals who did not develop disease Q.

5. 5 year case fatality rate for disease Q.

Answer 1

1.Prevalence rate of disease is a proportion of a particular population found to be affected by a medical condition at a specific time . prevalence rate= Number of existing cases+New cases /Population at risk *100.

2. Cumulative incidence of disease is measure of frequency of disease ,it is calculate as number of new events of disease divided by the total number of individuals in the population at risk for a specific time intervals.

3. Case fatality rate =Number deaths due to particular disease /Total affected population*100.