UCLA

Objective

African Americans (AA) suffer disproportionately from diabetic nephropathy (DN). C-reactive protein (CRP) has been associated with prevalent DN, but its association with incident DN in AA is unknown. We examined hs-CRP and incident DN in AA.

Research design and methods

We conducted a longitudinal analysis of data from exams 1, 2, and 3 in 4,043 eligible Jackson Heart Study (JHS) participants. Participants with DN or without hs-CRP at exam 1 were excluded. Incident DN was defined as urinary albumin-to-creatinine ratio (ACR) >30 mg/g or self-reported dialysis/transplantation and type 2 diabetes mellitus (DM) or HbA_1c >6.5% by exam 2 or 3 among participants free of DN at exam 1. Kaplan-Meier curves examined DN event-free survival probability by hs-CRP. With Cox proportional hazards regression we estimated hazard ratios (HRs) and 95% CI for DN by hs-CRP tertiles, adjusting for demographics and clinical and laboratory data.

Results

During 7.8 years of median follow-up time, participants who developed DN had significantly higher baseline hs-CRP, age, fasting glucose, triglycerides, ACR, systolic blood pressure, waist circumference, and duration of DM (P < 0.05). The overall incident rate of DN was 7.9%. The mean time to incident DN was shorter for participants with hs-CRP in the high tertile (>4.24 mg/L) than in the low tertile (<1.46 mg/L); P < 0.001. Participants with high hs-CRP had higher incidence of DN (HR 2.34, 95% CI 1.04-5.24) versus the reference group.

Conclusions

Inflammation, as measured by hs-CRP levels, may be associated with incident DN in AA. Further studies are warranted to replicate and elucidate the basis for this association.