Association of coronary heart disease mortality with risk factors according to length of follow-up and serum cholesterol level in men: the Oslo Study cohort

Aim: We aimed to clarify the strength of the association between conventional and metabolic risk factors to coronary heart disease (CHD) mortality across short, intermediate, and long periods of follow-up and whether the effects of risk factors are heterogeneous across serum cholesterol levels. Methods: The Oslo Study prospective cohort of 14,846 men aged 40–49 years was followed from screening in 1972–73 until 2006, during which time 1655 subjects died of CHD. Multivariate-adjusted Cox proportional models compared hazard ratios (HRs) and 95% confidence intervals (CIs) for CHD mortality across 0–12, 12–24, and 24–33 years of follow-up. Interactions between risk factors and quartile level of total serum cholesterol were assessed. Results: Total cholesterol, blood pressure, and cigarette smoking were associated with CHD mortality in multivariate analyses across all follow-up periods. Nonfasting triglyceride levels were associated with CHD in multivariate analyses (0–12 years, HR 1.12, 95% CI 1.00–1.25; 12–24 years, HR 1.13, 95% CI 1.04–1.23; 24–33 years, HR 1.09, 95% CI 1.00–1.19; 0–33 years, HR 1.10, 95% CI 1.05–1.16). A metabolic risk factor score (based on blood pressure, triglycerides, body mass index, and glucose) retained predictivity across all periods. The relations between systolic blood pressure, triglycerides, and metabolic risk factor score to CHD were stronger in the lower than the upper quartiles of serum cholesterol (p < 0.001). Conclusions: Conventional risk factors and nonfasting triglycerides increased CHD mortality across all periods of follow-up. The association with metabolic variables was strongest in men with low total cholesterol levels supporting the idea that lowering cholesterol should be the primary target of primary prevention.