Discriminant function analysis of factors related to myocardial infarction in male patients on antihypertensive therapy.

Records of 367 male patients who began attending the Dunedin Hospital Hypertension Clinic between 1959 and 1969 were coded up to the end of 1972. Of these patients, 60 had their first myocardial infarction, or sudden cardiac death without previous evidence of myocardial infarction, while they were attending the clinic. This infarct group was compared with a control group of 120 which was chosen from the remaining patients so that the two groups would be comparable with regard to their age and year of first attendance. A stepwise discriminant function analysis showed that the basal systolic and diastolic pressures measured when patients started attending the clinic were the variables with the most significant difference. Further analysis showed that inclusion of the average casual standing systolic pressure when patients were receiving antihypertensive therapy improved the discrimination between the groups. The average casual standing diastolic pressure during antihypertensive therapy also improved the discrimination, but, curiously enough, with a negative sign in the discriminant function. Quetelet's index of obesity similarly improved the discrimination, obese subjects having less risk of infarction or sudden death. Serum cholesterol, however, was not related to prognosis.