The role of a baseline casual blood pressure measurement and of blood pressure changes in middle age in prediction of cardiovascular and all-cause mortality occurring late in life: a cross-cultural comparison among the European cohorts of the Seven Countries Study.

OBJECTIVE: The first objective was to study the long-term association of a casual measurement of systolic blood pressure (SBP) with cardiovascular deaths (CVD) and all causes of death (ALL) occurring during 35 years of follow-up in different population samples of men aged 40-59 years in five European countries. The second objective was to study the predictive power of early change in SBP levels (years 0-10) in relation to late fatal events (years 10-35). DESIGN, SETTING AND PARTICIPANTS: A single measurement of SBP was considered in cohorts in Finland, The Netherlands, Italy, Serbia and Greece for a total of 6507 men. Three partitioned proportional hazards models were solved, one for each independent and subsequent time block of 10 years, after excluding data from the first 5 years, to predict the risk of cardiovascular disease deaths of atherosclerotic origin (CVD) and all cause mortality (ALL). Independently, the predictive power of SBP changes (Delta-SBP) occurred during the first 10 years of follow-up was explored as a possible additional risk factor in relation to CVD and ALL deaths occurring between year 10 and year 35 of follow-up.
RESULTS: Partitioned hazard scores derived from the three partitioned functions were cumulated. The resulting curves showed a continuous and significant association of baseline SBP with CVD and ALL deaths during three decades, although the strength of association declined significantly from the first to the third decade. The relative risk for 20 mmHg of SBP (and its 95% confidence intervals) in predicting CVD deaths was 1.65 (1.54-1.77) for the first 10-year block; 1.33 (1.24-1.42) for the second block; and 1.22 (1.13-1.31) for the last 10-year block. The corresponding levels of ALL deaths were 1.41 (1.34-1.49), 1.26 (1.19-1.32) and 1.11 (1.05-1.17). Changes in SBP during 10 years (Delta-SBP) added predictive power to baseline measurements in a direct and significant way, with a relative risk for a change of 10 mmHg of 1.14 (1.10-1.17) for CVD deaths and 1.11 (1.09-1.13) for ALL deaths.
CONCLUSION: A single measurement of systolic blood pressure in middle-aged men maintains a strong relationship with fatal CVD and ALL deaths during the next 35 years, although for late events the strength of the association definitely declines. Changes in systolic blood pressure levels during the first 10 years of follow-up add predictive power, while baseline measurements retain their predictive power.