The role of risk factor time trends in the steep decline of CHD mortality between two Israeli cohort studies

Background Over the past few decades, a sizable monotonous decrease in coronary heart disease (CHD) mortality rates was evident in Israel. Our purpose was to evaluate the association of risk factor time trends with this decline. Subjects and methods Data of two Israeli male cohorts with an inception date separated by 14 years were combined: (a) 9699 employees who participated in the Israeli Ischemic Heart Disease (IIHD) project, followed-up between 1965 and 1983, and (b) 1745 participants of the Glucose Intolerance, Obesity and Hypertension (GOH) study, sampled from the Central Population Registry, followed-up between 1979 and 1997. Results The mean age of both groups was comparable (52.9 vs. 51.2 years in the GOH and IIHD, respectively). Systolic blood pressure (133.5 vs. 138.1 mm/Hg), smoking (44% vs. 49%), and BMI (25.5 vs. 25.9 kg/m2) were lower in the GOH, whereas mean serum cholesterol was higher (215 vs. 208 mg/dL). During the follow-up period, 3,173 deaths were recorded. Of these, 968 (31%) were attributed to CHD. Overall mortality, adjusted by age and ethnic origin, was lower in the GOH (HR = 0.80, 95% CI: 0.72–0.89). CHD mortality was remarkably lower (HR = 0.55, 95% CI: 0.44–0.69). Adjusting for systolic blood pressure and smoking increased the HR for CHD death to 0.68 (95% CI: 0.55–0.85), whereas further adjustment for cholesterol reduced it slightly (HR = 0.63, 95% CI: 0.50–0.78). Conclusion Traditional risk factors appear to play a limited role in the declining rates of CHD mortality among Israeli males.