Sex-Specific Associations Between Complement Component 3 and Component 4 Levels and Metabolic Syndrome in an Adult...

Metabolic syndrome (MetS) is a cluster of cardiovascular and metabolic risk factors in the same individual. Inflammation has been reported to be directly involved in the development of metabolic disease. Complement component 3 (C3) and complement component 4 (C4) have been identified as important inflammatory markers relevant to metabolic disease. However, few studies have analyzed the association between C3 and/or C4 and MetS. In this study, our aim is to evaluate sex-specific association between C3 and C4 levels and risk of MetS in an adult population.

A cohort of 4635 adults was followed from 2010 to 2016. Serum C3 and C4 levels were measured using an immunonephelometric technique. MetS was defined by the American Heart Association scientific statements of 2009. Cox proportional hazard regression models were used to assess sex-specific association between C3 and C4 levels and the incidence of MetS.

During the ∼6 years of follow-up, 1445 new cases of MetS were identified. After being adjusted to confounding factors, the hazard ratios (95% confidence interval) of MetS for gradually increasing quintiles of C3 were 1.00, 1.23 (0.98-1.54), 1.50 (1.21-1.87), 1.64 (1.32-2.04), and 1.75 (1.41-2.18) (P for trend <0.0001) in men and 1.00, 0.96 (0.60-1.53), 1.61 (1.06-2.44), 2.01 (1.34-3.03), and 2.43 (1.63-3.63) (P for trend <0.0001) in women, respectively. Similar results were also obtained for gradually increasing quintiles of C4 in women, but not in men.

The levels of C3 were significantly associated with the incidence of MetS in both men and women. The levels of C4 contributed to risk of MetS only in women.