Objectives: In a 5-year multifactorial risk reduction intervention for healthy men with at least one cardiovascular disease (CVD) risk factor, mortality was unexpectedly higher in the intervention than the control group during the first 15-year follow-up. In order to find explanations for the adverse outcome, we have extended mortality follow-up and examined in greater detail baseline characteristics that contributed to total mortality.
Design: Long-term follow-up of a controlled intervention trial.
Setting: The Helsinki Businessmen Study Intervention Trial.
Participants and intervention: The prevention trial between 1974-1980 included 1,222 initially healthy men (born 1919-1934) at high CVD risk, who were randomly allocated into intervention (n=612) and control groups (n=610). The 5-year multifactorial intervention consisted of personal health education and contemporary drug treatments for dyslipidemia and hypertension. In the present analysis we used previously unpublished data on baseline risk factors and lifestyle characteristics.
Main outcome measures: 40-year total and cause-specific mortality through linkage to nation-wide death registers.
Results: The study groups were practically identical at baseline in 1974, and the 5-year intervention significantly improved risk factors (body mass index, blood pressure, serum lipids and glucose), and total CVD risk by 46% in the intervention group. Despite this, total mortality has been consistently higher up to 25 years post-trial in the intervention group than the control group, and converging thereafter. Increased mortality risk was driven by CVD and accidental deaths. Of the newly-analysed baseline factors, there was a significant interaction for mortality between intervention group and yearly vacation time (P=0.027): shorter vacation was associated with excess 30-year mortality in the intervention (hazard ratio 1.37, 95% CI 1.03-1.83, P=0.03), but not in the control group (P=0.5). This finding was robust to multivariable adjustments.
Conclusion: After a multifactorial intervention for healthy men with at least one CVD risk factor, there has been an unexpectedly increased mortality in the intervention group. This increase was especially observed in a subgroup characterised by shorter vacation time at baseline. Although this adverse response to personal preventive measures in vulnerable individuals may be characteristic to men of high social status with subclinical CVD, it clearly deserves further investigation.
Keywords: Multifactorial prevention; mortality; vacation.