Infections Following Kidney Transplantation After Exposure to Immunosuppression for Treatment of Glomerulonephritis.

RATIONALE & OBJECTIVE: Kidney transplant patients with glomerulonephritis (GN) as their native disease commonly have received pretransplant immunosuppression (PTI). This may contribute to the immunosuppression burden potentially increasing the risk for infections after transplantation. STUDY DESIGN: Single-center, retrospective cohort study. SETTING & PARTICIPANTS: Recipients of a kidney transplant from January 2005 until May 2020 at a tertiary care university teaching hospital. EXPOSURE: Patients with GN as their native kidney disease who received PTI for treatment of GN (n=184) were compared with nondiabetic recipients of kidney transplants who did not receive PTI (n = 579). OUTCOME: First occurrence after transplantation of an infection outcome, either viral (BK or cytomegalovirus [CMV] infection) or bacterial. ANALYTICAL APPROACH: Cox regression analysis adjusted for age at transplant, sex, race, donor type, year of transplant surgery, dialysis vintage, receipt of T-cell depleting induction, and CMV transplant status. RESULTS: Over a median follow-up period of 5.7 years, patients with GN PTI were not at an increased risk for developing any first viral infection compared with controls (adjusted HR [AHR] 0.69 [95% CI, 0.52-0.91]) nor at increased risk for specific viral infections: BK infection 19.6% vs 26.3% (AHR 0.72 [95% CI, 0.50-1.05]) or CMV infection, 24.5% vs 29.0% (AHR, 0.76 [95% CI, 0.54-1.07]), respectively. There was also no increased risk of developing a first bacterial infection: 54.5% vs 57.5% (AHR, 0.90 [95% CI, 0.71-1.13]). These findings of no increased risk for infection were independent of the type of PTI used (cyclophosphamide, rituximab, mycophenolate mofetil, or calcineurin inhibitor) or the type of T-cell depleting induction therapy (alemtuzumab or antithymocyte globulin) administered. LIMITATIONS: Single-center study, no data on methylprednisone use for PTI, unmeasured confounding. CONCLUSIONS: Use of PTI for the treatment of GN was not associated with an increased risk of viral (BK or CMV) or bacterial infection after transplantation. Additional surveillance for infection after transplantation for patients who received PTI may not be necessary. PLAIN-LANGUAGE SUMMARY: Many kidney transplant patients have glomerular disease as the cause of kidney failure. These patients may be exposed to immunosuppression before transplantation, which could increase the risk for infections after receipt of a transplanted kidney. We identified kidney transplant recipients at a university teaching hospital who received immunosuppression before transplant for the treatment of glomerular kidney disease. We examined their risk for infection after transplantation by comparing it with the risk among transplant patients who were not exposed to immunosuppression before transplant. We observed no increased risk for infection after exposure to prior immunosuppression. Therefore, patients exposed to significant amounts of immunosuppression before transplantation may not require special surveillance or medication adjustment for fear of infection after their receipt of a kidney transplant.

Precision nephrology identified tumor necrosis factor activation variability in minimal change disease and focal segmental glomerulosclerosis.

The diagnosis of nephrotic syndrome relies on clinical presentation and descriptive patterns of injury on kidney biopsies, but not specific to underlying pathobiology. Consequently, there are variable rates of progression and response to therapy within diagnoses. Here, an unbiased transcriptomic-driven approach was used to identify molecular pathways which are shared by subgroups of patients with either minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS). Kidney tissue transcriptomic profile-based clustering identified three patient subgroups with shared molecular signatures across independent, North American, European, and African cohorts. One subgroup had significantly greater disease progression (Hazard Ratio 5.2) which persisted after adjusting for diagnosis and clinical measures (Hazard Ratio 3.8). Inclusion in this subgroup was retained even when clustering was limited to those with less than 25% interstitial fibrosis. The molecular profile of this subgroup was largely consistent with tumor necrosis factor (TNF) pathway activation. Two TNF pathway urine markers were identified, tissue inhibitor of metalloproteinases-1 (TIMP-1) and monocyte chemoattractant protein-1 (MCP-1), that could be used to predict an individual's TNF pathway activation score. Kidney organoids and single-nucleus RNA-sequencing of participant kidney biopsies, validated TNF-dependent increases in pathway activation score, transcript and protein levels of TIMP-1 and MCP-1, in resident kidney cells. Thus, molecular profiling identified a subgroup of patients with either MCD or FSGS who shared kidney TNF pathway activation and poor outcomes. A clinical trial testing targeted therapies in patients selected using urinary markers of TNF pathway activation is ongoing.

Malignancy risk in kidney transplant recipients exposed to immunosuppression pre-transplant for the treatment of glomerulonephritis.

BACKGROUND: Kidney transplant patients with glomerulonephritis (GN) as their native disease may receive significant amounts of pre-transplant immunosuppression (PTI), which could increase the risk for development of malignancy post-transplant. METHODS: We conducted a single-center, retrospective study of kidney transplant recipients from January 2005 until May 2020. Patients with GN as their native kidney disease who received PTI for treatment of GN (n = 184) were compared with a control cohort (n = 579) of non-diabetic, non-PTI-receiving kidney transplant patients. We calculated hazard ratios (HR) with 95% confidence intervals (95% CI) for outcomes of first occurrence of solid or hematologic malignancy, non-melanoma skin cancer (NMSC) and post-transplant lymphoproliferative disorder (PTLD). RESULTS: Over a median follow-up of 5.7 years, PTI for GN was associated with significantly increased risk for malignancy compared with controls [13.0%  vs 9.7%, respectively; adjusted HR 1.82 (95% CI 1.10-3.00)], but not for NMSC [10.3% vs 11.4%, respectively; adjusted HR 1.09 (95% CI 0.64-1.83)] or PTLD [3.3% vs 3.1%, respectively; adjusted HR 1.02 (95% CI 0.40-2.61)]. The risk for malignancy was significantly increased in those who received cyclophosphamide [HR 2.59 (95% CI 1.48-4.55)] or rituximab [HR 3.82 (95% CI 1.69-8.65)] pre-transplant, and particularly in those who received both cyclophosphamide and rituximab, but not for calcineurin inhibitors or mycophenolate. CONCLUSION: The use of PTI for treatment of GN, especially cyclophosphamide or even with rituximab, is associated with increased risk for development of solid or hematologic malignancy post-transplant. These data highlight potential risks with treatment of GN and underscore the importance of post-transplant malignancy surveillance in this patient population.

Tobacco exposure in adults and children with proteinuric glomerulopathies: a NEPTUNE cohort study.

BACKGROUND: Tobacco exposure has been recognized as a risk factor for cardiovascular disease (CVD) and progression of kidney disease. Patients with proteinuric glomerulopathies are at increased risk for cardiovascular morbidity and mortality. Multiple studies have linked tobacco exposure to CVD and chronic kidney disease, but the relationships between smoking and proteinuric glomerulopathies in adults and children have not been previously explored. METHODS: Data from the Nephrotic Syndrome Study Network (NEPTUNE), a multi-center prospective observational study of participants with proteinuric glomerulopathies, was analyzed. 371 adults and 192 children enrolled in NEPTUNE were included in the analysis. Self-reported tobacco exposure was classified as non-smoker, active smoker, former smoker, or exclusive passive smoker. Baseline serum cotinine levels were measured in a sub-cohort of 178 participants. RESULTS: The prevalence of active smokers, former smokers and exclusive passive smoking among adults at baseline was 14.6%, 29.1% and 4.9%, respectively. Passive smoke exposure was 16.7% among children. Active smoking (reference non-smoking) was significantly associated with greater total cholesterol among adults (ß 17.91 95% CI 0.06, 35.76, p = 0.049) while passive smoking (reference non-smoking) was significantly associated with greater proteinuria over time among children (ß 1.23 95% CI 0.13, 2.33, p = 0.03). Higher cotinine levels were associated with higher baseline eGFR (r = 0.17, p = 0.03). CONCLUSION: Tobacco exposure is associated with greater risk for CVD and worse kidney disease outcomes in adults and children with proteinuric glomerulopathies. Preventive strategies to reduce tobacco exposure may help protect against future cardiovascular and kidney morbidity and mortality in patients with proteinuric glomerulopathies.

Glomerular Hematuria and the Utility of Urine Microscopy: A Review.

Evaluation of hematuria and microscopic examination of urine sediment are commonly used tools by nephrologists in their assessment of glomerular diseases. Certain morphological aspects of urine red blood cells (RBCs) seen by microscopy may help in identifying the source of hematuria as glomerular or not. Recognized signs of glomerular injury are RBC casts or dysmorphic RBCs, in particular acanthocytes (ring-shaped RBCs with protruding blebs). Despite being a highly operator-dependent test, urine sediment examination revealing these signs of glomerular hematuria has demonstrated specificities and positive predictive values ranging between 90%-100% for diagnosing glomerular disease, although sensitivity can be quite variable. Hematuria is a commonly used tool for diagnosing patients with proliferative glomerulonephritis such as IgA nephropathy, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, and lupus nephritis, sometimes even as a surrogate for kidney involvement. Studies examining the role for hematuria in monitoring and predicting adverse outcomes in these diseases have shown inconsistent results, possibly due to inconsistent definitions that often fail to consider specific markers of glomerular hematuria such as dysmorphic RBCs, acanthocytes, or RBC casts. A consensus definition of what constitutes glomerular hematuria would help standardize use in future studies and likely improve the diagnostic and prognostic value of hematuria as a marker of glomerulonephritis.

Black and White Adults With CKD Hospitalized With Acute Kidney Injury: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: Few studies have investigated racial disparities in acute kidney injury (AKI), in contrast to the extensive literature on racial differences in the risk of kidney failure. We sought to study potential differences in risk in the setting of chronic kidney disease (CKD). STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: We studied 2,720 self-identified Black or White participants with CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study from July 1, 2013, to December 31, 2017. EXPOSURE: Self-reported race (Black vs White). OUTCOME: Hospitalized AKI (≥50% increase from nadir to peak serum creatinine). ANALYTICAL APPROACH: Cox regression models adjusting for demographics (age and sex), prehospitalization clinical risk factors (diabetes, blood pressure, cardiovascular disease, estimated glomerular filtration rate, proteinuria, receipt of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers), and socioeconomic status (insurance status and education level). In a subset of participants with genotype data, we adjusted for apolipoprotein L1 gene (APOL1) high-risk status and sickle cell trait. RESULTS: Black participants (n = 1,266) were younger but had a higher burden of prehospitalization clinical risk factors. The incidence rate of first AKI hospitalization among Black participants was 6.3 (95% CI, 5.5-7.2) per 100 person-years versus 5.3 (95% CI, 4.6-6.1) per 100 person-years among White participants. In an unadjusted Cox regression model, Black participants were at a modestly increased risk of incident AKI (HR, 1.22 [95% CI, 1.01-1.48]) compared with White participants. However, this risk was attenuated and no longer significant after adjusting for prehospitalization clinical risk factors (adjusted HR, 1.02 [95% CI, 0.83-1.25]). There were only 11 AKI hospitalizations among individuals with high-risk APOL1 risk status and 14 AKI hospitalizations among individuals with sickle cell trait. LIMITATIONS: Participants were limited to research volunteers and potentially not fully representative of all CKD patients. CONCLUSIONS: In this multicenter prospective cohort of CKD patients, racial disparities in AKI incidence were modest and were explained by differences in prehospitalization clinical risk factors.

Longitudinal study of glomerular hyperfiltration and normalization of estimated glomerular filtration in adults with sickle cell disease.

Glomerular hyperfiltration is common in sickle cell disease (SCD) and precedes proteinuria and declining kidney function. We evaluated hyperfiltration in SCD patients and its "normalization." Routine visit data were collected retrospectively from adult SCD patients in a single centre from 2004 to 2013. Baseline was defined as first available serum creatinine and hyperfiltration as estimated glomerular filtration rates (eGFR) >130 ml/min/1·73 m2 for women and >140 ml/min/1·73 m2 for men. Normalization of hyperfiltration was eGFR reduction to 90-130 ml/min/1·73 m2 for women or 90-140 ml/min/1·73 m2 for men. Among 292 patients, median age was 27 years [interquartile range (IQR):20·0-38·0], and 56·8% had baseline hyperfiltration. Baseline hyperfiltration was inversely associated with age [odds ratio (OR):0·86, 95% confidence interval (CI): 0·82-0·90; P < 0·0001], male sex (OR:0·16, 95% CI: 0·07-0·41; P = 0·0001), haemoglobin (OR:0·76, 95% CI 0·61-0·94; P = 0·01), weight (OR:0·96, 95% CI: 0·93-0·99; P = 0·004), and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACE-I/ARB) use (OR:0·08, 95% CI: 0·01-0·75; P = 0·03), and positively with hydroxycarbamide use (OR:2·99, 95% CI: 1·18-7·56; P = 0·02). Of 89 hyperfiltration patients without baseline proteinuria, 10 (11·2%) developed new-onset proteinuria [median 1·05 years (IQR:0·63-2·09)]. Normalization of hyperfiltration was less likely with higher baseline eGFR [hazard ratio (HR):0·90, 95% CI: 0·86-0·95; P < 0·0001] and more likely in males (HR:6·35, 95% CI:2·71-14·86, <0·0001). Hyperfiltration is common in adult SCD patients, particularly when younger. Decline to normal values is more likely in males, possibly representing kidney function loss rather than improvement in hyperfiltration.

Rapid decline in estimated glomerular filtration rate in sickle cell anemia: results of a multicenter pooled analysis.

Not available.

APOL1 genotype-associated morphologic changes among patients with focal segmental glomerulosclerosis.

BACKGROUND: The G1 and G2 alleles of apolipoprotein L1 (APOL1) are common in the Black population and associated with increased risk of focal segmental glomerulosclerosis (FSGS). The molecular mechanisms linking APOL1 risk variants with FSGS are not clearly understood, and APOL1's natural absence in laboratory animals makes studying its pathobiology challenging. METHODS: In a cohort of 90 Black patients with either FSGS or minimal change disease (MCD) enrolled in the Nephrotic Syndrome Study Network (58% pediatric onset), we used kidney biopsy traits as an intermediate outcome to help illuminate tissue-based consequences of APOL1 risk variants and expression. We tested associations between APOL1 risk alleles or glomerular APOL1 mRNA expression and 83 light- or electron-microscopy traits measuring structural and cellular kidney changes. RESULTS: Under both recessive and dominant models in the FSGS patient subgroup (61%), APOL1 risk variants were significantly correlated (defined as FDR <0.1) with decreased global mesangial hypercellularity, decreased condensation of cytoskeleton, and increased tubular microcysts. No significant correlations were detected in MCD cohort. Independent of risk alleles, glomerular APOL1 expression in FSGS patients was not correlated with morphologic features. CONCLUSIONS: While APOL1-associated FSGS is associated with two risk alleles, both one and two risk alleles are associated with cellular/tissue changes in this study of FSGS patients. Our lack of discovery of a large group of tissue differences in FSGS and no significant difference in MCD may be due to the lack of power but also supports investigating whether machine learning methods may more sensitively detect APOL1-associated changes.

Role of direct oral anticoagulants in patients with kidney disease.

The anticoagulation field is experiencing a renaissance that began with regulatory approval of the direct thrombin inhibitor dabigatran, a direct oral anticoagulant (DOAC), in 2010. The DOAC medication class has rapidly evolved to include the additional approval of 4 direct factor Xa inhibitors. Commensurately, DOAC use has increased and collectively account for the majority of new anticoagulant prescriptions. Despite exclusion of patients with moderate-to-severe kidney disease from most pivotal DOAC trials, DOACs are increasingly used in this setting. An advantage of DOACs is similar or improved antithrombotic efficacy with less bleeding risk when compared with traditional agents. Several post hoc analyses, retrospective studies, claims data studies, and meta-analyses suggest that these benefits extend to patients with kidney disease. However, the lack of randomized controlled trial data in specific kidney disease settings, with their unique pathophysiology, should be a call to action for the kidney community to systematically study these agents, especially because early data suggest that DOACs may pose less risk of anticoagulant-related nephropathy than do vitamin K antagonists. Most DOACs are renally cleared and are significantly protein bound in circulation; thus, the pharmacokinetics of these drugs are influenced by reduced renal function and proteinuria. DOACs are susceptible to altered metabolism by P-glycoprotein inhibitors and inducers, including drugs commonly used for the management of kidney disease comorbidities. We summarize the currently available literature on DOAC use in kidney disease and illustrate knowledge gaps that represent important opportunities for prospective investigation.

Effect of renin-angiotensin-aldosterone system blocking agents on progression of glomerulopathy in sickle cell disease.

Although renin-angiotensin-aldosterone system (RAAS) blocking agents decrease albuminuria in short-term studies, there is no evidence confirming their long-term efficacy in sickle cell disease (SCD). In a single-centre, retrospective study, we evaluated the long-term effect of RAAS blocking agents on proteinuria and declining estimated glomerular filtration rates (eGFR). Eighty-six patients on RAAS blocking agents for proteinuria, followed for a median of 2·28 years, were compared with 68 patients with proteinuria followed for 2·24 years who were not receiving such treatment. The log odds of proteinuria decreased over time in patients on RAAS blocking agents (ß: -0·23, P = 0·03) and in the non-treatment group (ß: -0·54, P < 0·0001), but was not statistically different between both groups (ß: 0·31, P = 0·063). The eGFR declined over time in patients on RAAS blocking agents (ß: -2·78, P < 0·0001) and in those not on such treatment (ß: -4·7, P < 0·0001), and was statistically different between both groups (ß: 1·9, P = 0·0002). Baseline eGFR was associated with mortality (Hazard rato: 0·97, P < 0·0001), but RAAS blocking agents had no significant effect on mortality. These data suggest that RAAS blockade may slow the loss of kidney function in SCD.

Rapid decline in estimated glomerular filtration rate is common in adults with sickle cell disease and associated with increased mortality.

We evaluated the prevalence of rapid decline in kidney function, its potential risk factors and influence upon mortality in sickle cell disease (SCD) in a retrospective single-center study. Rapid decline of kidney function was defined as estimated glomerular filtration rate (eGFR) loss of >3·0 ml/min/1·73 m2 per year. A multivariable logistic regression model for rapid eGFR decline was constructed after evaluating individual covariates. We constructed multivariate Cox-regression models for rapid eGFR decline and mortality. Among 331 SCD patients (median age 29 years [interquartile range, IQR: 20, 41]; 187 [56·5%] female) followed for median 4·01 years (IQR: 1·66, 7·19), rapid eGFR decline was noted in 103 (31·1%). History of stroke (odds ratio [OR]: 2·91, 95% confidence interval [CI]: 1·25-6·77) and use of angiotensin converting enzyme inhibitors/angiotensin receptor blockers (OR: 3·17, 95% CI: 1·28-7·84) were associated with rapid eGFR decline. The rate of eGFR change over time was associated with mortality (hazard ratio [HR]: 0·99, 95% CI: 0·984-0·995, P = 0·0002). In Cox-regression, rapid eGFR decline associated with mortality (HR: 2·07, 95% CI: 1·039-4·138, P = 0·04) adjusting for age, sex and history of stroke. Rapid eGFR decline is common in SCD and associated with increased mortality. Long-term studies are needed to determine whether attenuating loss of kidney function may decrease mortality in SCD.

Progressive Decline in Estimated GFR in Patients With Sickle Cell Disease: An Observational Cohort Study.

RATIONALE & OBJECTIVE: Progression of chronic kidney disease (CKD) in sickle cell disease (SCD) and its risk factors remain poorly defined. We identified characteristics associated with CKD as well as decline in estimated glomerular filtration rate (eGFR) and presence of proteinuria over time in adults with SCD. STUDY DESIGN: Retrospective observational study. SETTING & PARTICIPANTS: Patients with SCD 18 years or older in a single center from 2004 to 2013. PREDICTORS: Baseline clinical and laboratory measures, comorbid conditions, SCD-related complications, relevant treatments, and severity of genotypes defined as severe (homozygous SCD [HbSS]/sickle-ß0-thalassemia [HbSß0]) or mild (hemoglobin SC disease [HbSC]/sickle-ß+-thalassemia [HbSß+]-thalassemia). OUTCOMES: Presence at baseline of CKD, defined here as eGFR<90mL/min/1.73m2 or proteinuria (≥1+) on urinalysis or current kidney transplant or dialysis therapy; change in eGFR; and presence of proteinuria over time. ANALYTICAL APPROACH: Logistic regression for baseline CKD. Linear mixed-effects model for eGFR decline and generalized linear mixed-effects model for proteinuria during the study period evaluating for interaction with time. Stratified by genotype severity. RESULTS: Among 427 patients, 331 had 2 or more measurements of creatinine. During a median follow-up of 4.01 (interquartile range, 1.66-7.19) years, annual eGFR decline was 2.05mL/min/1.73m2 for severe genotypes (P<0.001) and 1.16mL/min/1.73m2 (P=0.02) for mild genotypes. At baseline, 21.4% of patients with severe genotypes had CKD versus 17.2% of those with mild genotypes. For severe genotypes, angiotensin-converting enzyme-inhibitor/angiotensin receptor blocker use (OR, 6.10; 95% CI, 2.03-18.29; P=0.001) and avascular necrosis (OR, 0.40; 95% CI, 0.16-0.97; P=0.04) were associated with baseline CKD. Among those with mild genotypes, higher hemoglobin level was associated with lower probability of CKD (OR per 1-g/dL greater hemoglobin level, 0.63; 95% CI, 0.43-0.93; P=0.02). Rate of eGFR decline was inversely related to hemoglobin level (ß = 0.46 [SE, 0.23]; P=0.04) within the severe genotype subgroup. No factors were identified to be associated with proteinuria over time. LIMITATIONS: Retrospective observational study, limited direct measures of albuminuria. CONCLUSIONS: Patients with SCD exhibit rapid decline in eGFR over time. Decline in eGFR is associated with markers of disease severity and associated comorbid conditions.

Thirty-year risk of ischemic stroke in individuals with sickle cell trait and modification by chronic kidney disease: The atherosclerosis risk in communities (ARIC) study.

Sickle cell trait (SCT) has been associated with hypercoagulability, chronic kidney disease (CKD), and ischemic stroke. Whether concomitant CKD modifies long-term ischemic stroke risk in individuals with SCT is uncertain. We analyzed data from 3602 genotyped black adults (female = 62%, mean baseline age = 54 years) who were followed for a median 26 years by the Atherosclerosis Risk in Communities Study. Ischemic stroke was verified by physician review. Associations between SCT and ischemic stroke were analyzed using repeat-events Cox regression, adjusted for potential confounders. SCT was identified in 236 (7%) participants, who more often had CKD at baseline than noncarriers (18% vs 13%, P = .02). Among those with CKD, elevated factor VII activity was more prevalent with SCT genotype (36% vs 22%; P = .05). From 1987-2017, 555 ischemic strokes occurred in 436 individuals. The overall hazard ratio of ischemic stroke associated with SCT was 1.31 (95% CI: 0.95-1.80) and was stronger in participants with concomitant CKD (HR = 2.18; 95% CI: 1.16-4.12) than those without CKD (HR = 1.09; 95% CI: 0.74-1.61); P for interaction = .04. The hazard ratio of composite ischemic stroke and/or death associated with SCT was 1.20 (95% CI: 1.01-1.42) overall, 1.44 (95% CI: 1.002-2.07) among those with CKD, and 1.15 (95% CI: 0.94-1.39) among those without CKD; P for interaction = .18. The long-term risk of ischemic stroke associated with SCT relative to noncarrier genotype appears to be modified by concomitant CKD.

Sickle Cell Trait and the Risk of ESRD in Blacks.

Blacks, compared with whites, have an increased risk of progression to end-stage renal disease (ESRD). Emerging evidence suggests that, in addition to APOL1 high-risk genotypes, hemoglobin variants, including sickle cell trait (SCT) and hemoglobin C trait, have a role in kidney disease in blacks. However, the association between these hemoglobin traits and ESRD remains unknown. In a large population-based cohort, the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, we evaluated 9909 self-reported blacks (739 with SCT and 243 with hemoglobin C trait). Incident ESRD occurred in 40 of 739 (5.4%) individuals with SCT, six of 243 (2.5%) individuals with hemoglobin C trait, and 234 of 8927 (2.6%) noncarriers. The incidence rate for ESRD was 8.5 per 1000 person-years for participants with SCT and 4.0 per 1000 person-years for noncarriers. Compared with individuals without SCT, individuals with SCT had a hazard ratio for ESRD of 2.03 (95% confidence interval, 1.44 to 2.84). Hemoglobin C trait did not associate with prevalent CKD or ESRD. The incidence rate for ESRD among participants with APOL1 high-risk genotypes was 6.6 per 1000 person-years, with a hazard ratio for ESRD of 1.77 (95% confidence interval, 1.31 to 2.38) for participants with, compared with those without, APOL1 high-risk genotypes. In this cohort, SCT strongly associated with risk of progression to ESRD in blacks, and this degree of risk for ESRD was similar to that conferred by APOL1 high-risk genotypes. These results may have important public policy implications for genetic counseling of SCT carriers.