Analysis of total mortality in the Rotterdam sample of the Kaunas-Rotterdam Intervention Study (KRIS)

In 3284 middle-aged Rotterdam men, the dependency of 9-year survival on a number of cardiovascular risk factors is analysed. The purpose of this analysis is twofold. First, there is interest in the relationship between total mortality and the continuous variables blood pressure and plasma cholesterol. In accordance with other studies, the results provide further evidence for a U-shaped relationship. The second purpose is to compare three models theoretically as well as empirically: a piecewise exponential distribution of survival time, Cox's proportional hazards model (both with a long-linear dependency specification of the mortality rate), and a logistic model. The disadvantage of a logistic model is that it is theoretically not appropriate in longitudinal (prospective) epidemiologic studies. The theoretical advantage of the piecewise exponential distribution to Cox's model is that longitudinal (time) effects on the mortality rate can be specified and estimated directly. Empirically, with 342 deaths all three methods yield quite similar estimates and therefore are almost equally capable of detecting relationships between mortality and the risk factors in the data set at hand.