Informativeness of indices of blood pressure, obesity and serum lipids in relation to ischaemic heart disease mortality: the HUNT-II study

Bjørn Mørkedal, Pål R Romundstad, Lars J. Vatten

The informativeness of blood pressure, obesity and serum lipids associated with cardiovascular events may depend on how the indices are expressed, and mid blood pressure, waist-to-hip ratio adjusted for body-mass index (BMI) and the ratio of total to HDL cholesterol may be more informative than other expressions. Our aim was to study the informativeness of indices of blood pressure, obesity and serum lipids associated with ischaemic heart disease mortality in a large, homogeneous population. Blood pressure, weight, height, waist and hip circumference, total and HDL cholesterol, and triglycerides were measured at baseline (1995-1997) in 28,158 men and 32,573 women. Information on deaths from ischaemic heart disease (IHD) was obtained from the Causes of Death Registry in Norway from baseline until the end of 2007. Informativeness was analysed using the difference in twice the log-likelihood of a Cox model with and without each index. During 11 years of follow-up, 597 men and 418 women had died from IHD. Systolic blood pressure in men and pulse pressure in women were the most informative predictors of blood pressure, and waist-to-hip ratio adjusted for BMI was the most informative expression of obesity in both men and women. Among serum lipids, the most informative predictor was the ratio of total cholesterol to HDL cholesterol. Using more informative expressions of conventional risk factors for ischemic heart disease may improve both the validity and precision of estimates of risk, and may be useful both clinically and for preventive purposes.