Long term changes in blood pressure and risk of cerebrovascular disease.

Little attention has been given to assessing risk factors for cerebrovascular disease (CBVD) and less has been given to relatinglong term changes in blood pressure (BP) to CBVD occurrence. In the Manitoba Study811 a cohort of 3,983 North American men (predominantly between 25-34 years of age at entry in 1948), measured 5 times during the 26 year observation period from 1948 to 1974, was related tothe incidence of CBVD. Used were measurements of age, systolic (SBP) and diastolic (DBP) blood pressure and Body Mass Index-weight/height2 determined at entry and at examination closest to July 1, 1954, 1959, 1964 and 1969. Change was calculated as the difference in these variables between examinations. In order to adjust for age and BP as CBVD risk factors, as well as for the effect both may have on the rate of BP change, the data were analyzed using multivariate as well as univariate methods. After adjusting for age and SBP, change in SBP was significantly associated with subsequent CBVD, primarily in men middle aged or older. When considering SBP after entry, changes from a measurement 5 yearsearlier were more important than SBP changes over longer intervals. Thus, in evaluating SBP as a risk factor for CBVD, the rate of change in SBP is also an important factor in the identification of the stroke prone individual.