Question

1. The following health statistics are available on the Internet for country Z about two disease outcomes. Disease A has an annual incidence rate of 225 per 100,000 population and an annual mortality rate of 150 per 100,000. Disease B has an annual incidence rate of 500 per 100,000 population and the same annual mortality rate as Disease A. Neither disease has a cure. What would you conclude regarding the burden of these diseases in country Z?
   1. The proportionate mortality is higher for disease A than disease B.
   2. Disease A has a higher prevalence than disease B.
   3. Disease B has a higher prevalence than disease A.
   4. The case fatality ratio is higher for disease B than disease A.
   5. Years of potential life lost (YPLL) is greater for disease B than disease A.

Answer 1

1. Mortality rate is same for Disease A and B in that particular year. Proportionate Mortality rate PMR = (No of deaths in a given time due to a particular disease / total number of deaths during that time) x 100. So Option A is wrong.
2. Option B is wrong. Disease A has lower prevalence rate (225 per 100,000) than disease B (500 per 100,000). Prevalence rate = Total number of cases in a given time/total population.
3. Option C is right. Prevalence rate of disease B (500 per 100,000) is higher compared to that of disease A (225 per 100,000)
4. Option D is wrong. Case fatality ratio is the proportion of deaths due to a particular disease compared to the total number of peoples diagnosed with the disease. Case fatality ratio = no of deaths due to a disease / no of cases of a particular disease. 0.3 is the case fatality rate of disease B (150/500) and that of disease A is 0.7 (150/225). So case fatality rate is high for disease A than disease B.
5. YPLL is estimated life span or the average years a person would have lived unless he died prematurely of a particular disease. It measures the premature mortality rate. For this age of death needs to be available. YPLL = persons age at death - reference age (expected life span). Here the mortality corresponding to various age groups is not given. so this option is not applicable.