腎臓学と治療学ジャーナル

Relationship of Race and Proteinuria to Renal Function Decline in Patients with CKD

Abstract

Steven Rosansky *,Martin Durkin ,James Hardin ,Kirby Jackson ,Csaba Kovesdy ,Jessica Sontrop ,Justin Reynolds ,Kathlyn Haddock ,Frankie Richards ,William Clark

Background: To date, the reasons for the higher rates of treated end-stage renal failure in blacks versus whites are poorly understood. Proteinuria is the most important determinant of renal function loss (RFL). Blacks have a higher incidence of proteinuric CKD than whites. The current study evaluates the hypothesis that after adjustment for proteinuria, blacks have faster RFL, more prominent at lower levels of estimated glomerular filtration rates (eGFR). Methods: In a non-referral outpatient CKD population of 1,935 blacks and 6,286 whites, the relationship of zero, <2 plus and ≥ 2 plus dipstick proteinuria to MDRD e GFR change per year (RFL) was analyzed. Next the relationship between race and RFL was examined in patients with higher versus lower eGFR (defined by never or ever having an eGFR <30 ml/min/1.73 m2, respectively during the study using a mixed effects model which includes longitudinal urinalysis (log converted), serum creatinine data points, age and whether a patient died during the study. Results: Versus whites, blacks had higher baseline e GFR (75.3 ml/min/1.73 m2 versus 64.9 ml/min/1.73 m2) higher frequency of e GFR <30 ml/min/1.73 m2 (30.8% versus 21%), higher dipstick proteinuria levels and faster RFL by proteinuria group (range -1.07 to -2.28 ml/min/m2/year in blacks and -0.68 to -1.80 ml/min/1.73 m2/ year, in whites), p< 0.01. In the mixed effects model, blacks had a 0.30 and 0.59 ml/min/1.73 m2/ year, faster loss of renal function in the higher and lower eGFR groups, respectively, p< 0.001. Conclusion: Blacks with CKD appear to lose renal function faster than whites. This effect may be more pronounced at lower e GFR levels.