Effects of weight loss and risk factor treatment in subjects with elevated serum C3, an inflammatory predictor of myocardial infarction

Background Serum C3 is an inflammatory predictor of myocardial infarction and a covariate of fasting insulin and several endogenous risk factors. This study was performed to ascertain whether risk factor control may reduce elevated C3 concentrations. Methods After traditional risk factor and C3 assessment in 1100 unselected men aged 55–64 years, 238 men with persistently elevated C3 levels (>=1.19 g/l, high tertile) were randomised into 2 groups: 43 controls, who were referred to their general practitioner, and 195 subjects who were intensively treated with diet, and anti-hypertensive or antidiabetic drugs according to specific indications, without anti-dyslipidemic drugs. Results After three months in the treated subjects significant decrements of body weight, blood pressure, blood glucose and serum lipids were obtained, with stable C3 levels (while in controls a 3.3% increase occurred, P=0.02). The factors associated with a C3 decrement >5% were a high baseline C3 level, a recent acute inflammation, physical activity, belonging to the treated group, and a significant reduction in body weight, triglycerides or blood glucose. However, in multivariate analysis only an elevated baseline C3 (P<0.0001), a weight loss >2% (P=0.0009) and physical activity (P=0.02) remained independently associated with a C3 decrement >5% (R2=0.14). Conclusions Only weight loss and physical activity, but not traditional risk factor lowering, could independently induce a significant C3 decrease. Thus, C3 elevation is associated with, but probably not caused by, traditional risk factors.