Acute Kidney Injury among Black Patients with Sickle Cell Trait and Sickle Cell Disease

Abstract

Background and objectives: Sickle cell trait and sickle cell disease are associated with faster GFR decline compared with normal hemoglobin phenotypes. We sought to compare the AKI risk in sickle cell trait/disease to normal hemoglobin phenotypes and investigate the association between AKI and GFR decline in sickle cell trait/disease.

Design, setting, participants, & measurements: This multicenter observational study used registry data (January 2005-June 2018) of adult Black patients with sickle cell trait/disease (exposures) and normal hemoglobin phenotype (reference) ascertained by hemoglobin electrophoresis. Outcomes of interest (incident AKI [1.5 times baseline serum creatinine or higher], incident severe AKI [doubling of baseline serum creatinine or higher], and incident sustained AKI [AKI persisting for ≥72 hours]) were adjudicated by chart review and evaluated by Cox regression. The association between AKI and GFR decline (linear mixed models) was also investigated.

Results: We identified 8968 reference patients, 1279 patients with sickle cell trait, and 254 patients with sickle cell disease with a median follow-up of 7.6 years and mean baseline serum creatinine of 0.8 mg/dl. We observed 796 AKI events, 452 sustained AKI events, and 466 severe AKI events. Compared with people with a normal hemoglobin phenotype, sickle cell trait was associated with higher risk for sustained AKI (adjusted hazard ratio, 1.64; 95% confidence interval, 1.27 to 2.11), but not AKI (adjusted hazard ratio, 1.11; 95% confidence interval, 0.91 to 1.36) or severe AKI (adjusted hazard ratio, 1.26; 95% confidence interval, 0.96 to 1.64). Sickle cell disease was associated with AKI (adjusted hazard ratio, 2.85; 95% confidence interval, 2.13 to 3.81), severe AKI (adjusted hazard ratio, 2.38; 95% confidence interval, 1.65 to 3.42), and sustained AKI (adjusted hazard ratio, 2.50; 95% confidence interval, 1.68 to 3.71). Post-AKI GFR decline was significantly faster in sickle cell trait (0.37 ml/min per 1.73 m² per year faster, P<0.01) and disease (1.69 ml/min per 1.73 m² per year faster, P<0.01) compared with the reference.

Conclusions: Sickle cell trait and disease are associated with higher risk of AKI, which is associated with accelerated decline in eGFR.

Keywords: AKI; Black race; eGFR decline; hazard ratio; incidence; sickle cell disease; sickle cell trait.