C-reactive protein and microalbuminuria in a multi-ethnic Asian population

Background. C-reactive protein (CRP), a marker for inflammation, has been recently associated with early kidney damage. We examined the association between CRP and micro/macroalbuminuria in a multi-ethnic Asian population using data from two population-based studies in Singapore. Methods. We studied 5127 individuals, who participated in two separate, cross-sectional studies, the Singapore Prospective Study Program [SP2]/Singapore Cardiovascular Cohort Study 2 (SCCS2), involving 4233 participants of Chinese, Malay and Indian ethnicity, aged 24-95 years in Singapore, and the Singapore Malay Eye Study (SiMES), involving 894 participants of Malay ethnicity, aged 40-80 years. Micro/macroalbuminuria was defined as urinary albumin-to-creatinine ratio of >= 17 mg/g for men and >= 25 g/g for women. CRP was analyzed as a continuous variable and as categories (<1, 1-3, >3 mg/L). Results. The prevalence of micro/macroalbuminuria in the whole population was 21.1%. The prevalence increased with increasing categories of CRP. Compared with persons with CRP concentrations <1 mg/L, the multivariable odds ratio (OR) (95% confidence interval [CI]) was 1.33 (1.11-1.60) in persons with CRP concentrations 1-3 mg/L and 1.60 (1.30-1.96) in persons with CRP concentrations >3 mg/L; P trend <0.0001. In continuous analysis, each unit increase in log CRP was associated with an OR (95% CI) of 1.20 (1.11-1.28) of having micro/macroalbuminuria (P < 0.0001). This association was independent of potential confounders and was consistent across the two study cohorts with similar effect estimates (OR = 1.6) for micro/macroalbuminuria. Conclusions. Elevated CRP levels are associated with micro/macroalbuminuria independent of diabetes, hypertension and other potential confounders. This suggests that inflammation may play a role in early kidney damage.