Cause-Specific Mortality Rates in Chronic Disease Populations

Random sample surveys have been used for public health surveillance for about 50 years and have grown in size over that time. Such surveys are sufficiently large to estimate the sizes of relatively small subpopulations, such as patients with chronic diseases, helped by pooling multiple years of the same survey. Survey estimates of population sizes have been used as denominators to estimate death rates from specific causes within specific subpopulations. Since these are ratio estimates, with both numerator and denominator being estimates, additional examination is required to evaluate their reliability. We illustrate these methods for rates using deaths due to diabetes and the estimated population of diabetics to compute death rates due to diabetes among diabetics by age and sex. Substituting the much smaller population of people at risk for the total population yields useful information about the burden of disease.