Computerised record linkage: Compared with traditional patient follow-up methods in clinical trials and illustrated in a prospective epidemiological study

To determine the effects of lowering cholesterol concentrations on total and cause specific mortality in randomised primary prevention trials. Qualitative (meta-analytic) evaluation of total mortality from coronary heart disease, cancer, and causes not related to illness in six primary prevention trials of cholesterol reduction (mean duration of treatment 4.8 years). 24,847 Male participants; mean age 47.5 years. Total and cause specific mortalities. Follow up periods totalled 119,000 person years, during which 1147 deaths occurred. Mortality from coronary heart disease tended to be lower in men receiving interventions to reduce cholesterol concentrations compared with mortality in control subjects (p = 0.06), although total mortality was not affected by treatment. No consistent relation was found between reduction of cholesterol concentrations and mortality from cancer, but there was a significant increase in deaths not related to illness (deaths from accidents, suicide, or violence) in groups receiving treatment to lower cholesterol concentrations relative to controls (p = 0.004). When drug trials were analysed separately the treatment was found to reduce mortality from coronary heart disease significantly (p = 0.04). The association between reduction of cholesterol concentrations and deaths not related to illness warrants further investigation. Additionally, the failure of cholesterol lowering to affect overall survival justifies a more cautious appraisal of the probable benefits of reducing cholesterol concentrations in the general population.

The relationship between ethanol consumption and coronary heart disease was examined in the original Framingham Heart Study cohort (1948) with a 24-year follow-up from exam 2 (2,106 males and 2,639 females). Ethanol consumption shows a strong U-shaped relationship with coronary heart disease mortality for male nonsmokers and heavy smokers both in the raw age-adjusted data and in the Cox regression analyses, where ethanol consumption is modeled quadratically. No ethanol effects were found for female nonsmokers. The age-adjusted data suggest a U-shape curve for female smokers, although this was not confirmed by the Cox analysis. Separate analyses relating alcohol consumption to mortality from all causes showed similar effects except that the reduction in mortality for males was much less. For male coronary heart disease mortality, ethanol consumption was subdivided into beer, wine, and spirits consumption. These beverages were also modeled quadratically in the Cox analyses, and all showed strong U-shaped curves for both nonsmokers and heavy smokers. In nonsmokers, beer and wine show greater reductions in coronary heart disease mortality than spirits.