Blood pressure and mortality during an up to 32-year follow-up

BACKGROUND: Elevated blood pressure is an established risk factor of cardiovascular diseases, but there is a constant debate whether the association is continuous or with a threshold. METHODS: During the 1960s (1964 onwards), 3,267 initially healthy male business executives (born 1919-1934) participated in voluntary health check-ups with measurements of cardiovascular disease risk factors. At baseline none of the men were on antihypertensive medication. Mortality follow-up was performed using national registers up to 31 December, 1995. Follow-up total and cardiovascular mortality was related to systolic (by 10 mmHg) and diastolic (by 5 mmHg, Korotkoff's 4th phase) blood pressure at baseline. Analyses were adjusted for age, body mass index, smoking and serum cholesterol. RESULTS: During an up to 32-year follow-up, there were 701 deaths, 234 (33.4%) of them due to coronary heart disease, 49 (7.0%) to stroke, 42 (6.0%) to other cardiovascular diseases and 204 (29.1%) to cancer. Total mortality curves of the whole cohort (all age groups) were flat until 131-140 mmHg (systolic) and 81-85 (diastolic) and increased thereafter. Among men who smoked and had baseline serum cholesterol > 6.5 mmol/l (n = 986), the risk of death increased progressively with systolic blood pressure, whereas among non-smoking normocholesterolaemic men (n = 504) the association was J-shaped, i.e. higher mortality at < or = 110 mmHg than between 111-150 mmHg and a more consistent rise from 151-160 mmHg. The curves were essentially similar for cardiovascular mortality. The results were supported by analyses where major cardiovascular risk factors were controlled. CONCLUSION: During a truly long-term follow-up, the relationship between systolic blood pressure and mortality was initially flat up to 131-140 mmHg although a linear relationship is suggested in men with other cardiovascular risk factors.