Distributions of C-reactive protein and its association with metabolic syndrome in middle-aged and older Chinese people

Objectives We evaluated the distributions of C-reactive protein (CRP) and its association with metabolic syndrome (MetS) in middle-aged and older Chinese people. Background Several studies have suggested that CRP is a risk factor of MetS. However, it remains unclear how CRP levels are distributed and whether they are associated with MetS in Chinese people. Methods We conducted a population-based cross-sectional survey in 2005 in Beijing and Shanghai, with a total of 1,458 men and 1,831 women age 50 to 70 years. Metabolic syndrome was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans. Results The median CRP level was 0.68 mg/l among the study population. The CIRP levels were significantly higher among participants from Beijing or from urban areas than those in participants from Shanghai or from rural areas (p < 0.01). No gender difference in CRP levels was observed. The prevalence of MetS progressively increased with elevated CRP levels (p < 0.0001 for trend). In the highest quartile of CRP levels (> 1.50 mg/l), the risk for MetS was substantially higher (odds ratio 5.97; 95% confidence interval 4.75 to 7.51) compared with that in the lowest quartile of CRP levels (<= 0.33 mg/l) after adjustment for age, gender, geographic location, lifestyle factors, educational attainment, and family history of chronic diseases. This association was observed in both obese and nonobese participants. Conclusions The overall plasma level of CRP is low but highly associated with the MetS among the middle-aged and elderly Chinese population. Prospective studies are needed to investigate the role of CRP in the development of MetS and related chronic diseases among Chinese people.