PubMed1986
Risk factors for definite hypertension were examined using data from two Italian rural cohorts from the Seven Countries Study, originally composed of 1,712 men ages 40-59 at entry. Two approaches were used: cross-sectional examination of baseline exposure/outcome measurements; and prospective examination of data, correlating baseline measurements with subsequent definite hypertension, diagnosed at the 10-year follow-up exam. Hypertension was defined as diastolic blood pressure greater than or equal to 95 mm Hg or systolic blood pressure greater than or equal to 160 mm Hg. Included in the cross-sectional analysis were 1,437 subjects free from other cardiovascular diseases at baseline. Of these, 590 were included in the prospective analysis. Using a multiple logistic function that did not include baseline (normal) blood pressure, age, pulse rate, and weight were confirmed as risk factors for hypertension both cross-sectionally and prospectively, thus suggesting that bias cannot explain the relationship of hypertension to these factors. Although proteinuria and vital capacity were associated with hypertension in the cross-sectional analysis, no such relationships were detected prospectively, thus implying that these factors are effects, rather than determinants, of definite hypertension. Smoking had a negative prospective (but not cross-sectional) association with hypertension, which can probably be explained by survival bias at 10 years after ascertainment of smoking habits. When mean baseline blood pressure was added to the prospective multiple logistic function, it became the only factor significantly associated with hypertension (P less than 0.001), again confirming the importance of "tracking" in the determination of hypertension.