Question

Data on incidence is usually the most useful for identifying important etiologic (causative) and preventive factors for a condition. However, because of the societal and legal importance of death, mortality data are much more available than incidence data. Under what circumstances is the mortality rate for a disease a good reflection of the incidence rate for that disease? Would you say that such circumstances apply for CHD death rates? Discuss the consequences of your answer in regard to the objectives (not the results) of this study

Answer 1

The basic elements of an epidemiological study can as follows:

• formulation of the study question or hypothesis
• selection of study populations and study samples
• selection of indicators of exposure
• measurement of exposure and disease
• analysis of the relationship between exposure and disease
• evaluation of the role of bias
• evaluation of the role of chance.

A mortality rate is a good reflection of the incidence rate under two conditions

• First when the case fatality rate is high
• When the duration of disease is short

Under these conditions, mortality is a good measure of incidence, and thus a measure of the risk of disease.

Case fatality rate-Any specified time interval is specified for incidence rate is case fatality rate.

In case CHD we can't able to decide the interval and also the duration of disease is long term so these circumstance can't be applied.