Racial Adjustment Adversely Affects Glomerular Filtration Estimates in African Americans Living with HIV
Background The creatinine-based CKD EPI equation is the most widely used method to estimate glomerular filtration rate (eGFRcr) in clinical practice. Here, we focus on African American (AA) participants to determine whether the race eGFRcr calibration factor contributes to poor accuracy and bias in AAs living with HIV. Methods Annually, we measured GFR by iohexol disappearance from plasma (iGFR) and serum concentrations of creatinine and cystatin C. We calculated eGFRcr and the creatinine-cystatin C combination equation (eGFRcr-cys) with and without race adjustment. We used multilevel mixed models to account for the within-visit linked structure of the multiple GFR measures, further nested within repeated observations for individuals. We examined the association between lean mass, HIV status, and eGFRcr bias in a subset with body composition measures. Results 207 HIV-positive and 107 HIV-negative AA participants contributed 781 and 376 study visits, respectively, with valid measures of iGFR, creatinine, and cystatin C. Among PLWH, omitting the race adjustment (compared with retaining it) changed average eGFRcr bias from 9.1 to -3.9 ml/min/1.73 m2. Moreover, estimation accuracy improved significantly when race adjustment was omitted rather than retained: 86% vs. 78% for eGFRcr (P<0.001) and 91% vs. 88% for eGFRcr-cys (P=0.045). Lean mass was correlated with eGFRcr bias and, in adjusted analyses, lean mass was significantly lower in PLWH compared with HIV-negative AAs compatible with not using the race coefficient. Conclusions We found that the standard, widely used eGFRcr equation overestimate iGFR and has poor accuracy in AAs living with HIV.