Modeling of risk factors for ischemic stroke. The Willis Lecture.

Abstract

It is a pleasure for me to give the Willis Lecture. I am especially honored because at the 8th Conference in February 1983 I also gave the Keynote Address, before it became known as the Willis Lecture.1 I am going to discuss a few principles concerning the risk factors for stroke; some recent observations from the Rochester, Minnesota, population on modeling of stroke risk factors; and some new observations about modeling attributable risk for stroke risk factors in a multivariable analysis; and I shall discuss how we might consider the risk factors for stroke in regard to the pathologic substrates for stroke. The Rochester Epidemiology Project medical record linkage system2 provided the means to identify virtually all new cases of ischemic stroke in the Rochester population for a population-based, nested case-control study of risk factors for stroke. The controls for the study were selected from an enumeration of the population through the medical records of the Rochester Epidemiology Project. There were 1444 incidence cases of stroke in the population in the 25 years of the study from 1960 through 1984, with controls from the population matched one-to-one by age, sex, and duration of the medical record. About 80% of the cases were seen and evaluated by a neurologist. This study of risk factors for ischemic stroke provides a unique and powerful set of data because it includes such a large number of incident cases and population-based controls. The size of the data set allowed assessment of interactions that have not been assessed adequately. More details of this study were published in December 1996.3 The effect of a risk factor on the probability of stroke is determined by three considerations: (1) the relative risk of the factor, (2) the prevalence of the factor in the population, and (3) …