Biological predictors of change in functioning in the Whitehall II study

To examine whether risk factors for CHD are related to change in functioning independent of the presence or development of disease.

Longitudinal follow up of 4768 men and 2034 women civil servants from 20 London-based departments with complete data for the SF-36, biological variables, and BMI and health related behaviors. Data are used from two phases of the Whitehall II study, phase 3 (1991-1993) and phase 4 (1995) with an interval of 36 months. Weight, height, fasting insulin, 2-hour post load glucose, total and HDL-cholesterol, fibrinogen, von Willebrand factor, diastolic and systolic blood pressure, and waist hip ratio were measured at phase 3. Demographic and socio-economic information, health related behaviors, and the SF-36 were obtained at both phases by questionnaire.

Waist hip ratio, fasting insulin, triglycerides, and HDL-cholesterol were associated with a decline in physical functioning in the total cohort and when those with poor health at baseline were removed from the analyses. Principal component analysis revealed that these variables clustered with total cholesterol and may represent insulin resistance. The biological variables had a cumulative effect on decline in physical functioning such that those with poor waist hip ratio, fasting insulin, triglycerides, and HDL-cholesterol was two times greater than those without. This relationship was independent of exercise, smoking, and alcohol intake which explained only 17% and 5.4% of the association in men and women, respectively.

A number of biological variables, which may represent insulin resistance, are associated with decline in physical functioning in men and women independent of prevalent ill health or health related behaviors.