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Introduction Individuals with sickle cell disease (SCD) in resource-rich countries are now living longer due to the implementation of newborn screening, use of prophylactic penicillin, and introduction of hydroxyurea. The impact of SCD on the bone marrow and peripheral blood counts as individuals with SCD age is not well described in the hydroxyurea era. As a result of increased red blood cell (RBC) turnover due to hemolysis in SCD, potential ineffective erythropoiesis, and well-described systemic inflammatory processes, the increased stress in the bone marrow may manifest as decreased peripheral blood cell counts over time in a during an aging process unique to those with SCD. Objective The objective was to model routine clinical blood measurements (n=5,328) with a longitudinal cohort of 447 patients, resulting in models of circulating blood counts as a potential marker of bone marrow function across the lifespan in adults with SCD. Our working hypothesis was that increasing age would be associated with decreases in certain blood counts, with trends modified by SCD genotype severity. Methods In this large, single institution retrospective cohort study, we analyzed blood count measurements from adults with SCD. We used an accelerated longitudinal cohort design to examine changes in white blood cell count (WBC), hemoglobin (HGB), absolute reticulocyte count (ARC), and platelet count over time. Genotypes were grouped as severe (HbSS or HbSβ 0-thalassemia; n=301), non-severe (HbSC or HbSβ +-thalassemia; n=136), or other (n=10). For HGB and ARC, we adjusted for estimated glomerular filtration rate (eGFR) and serum creatinine. Results Patients ranged in age at enrollment from 18 to 84 (M = 31.9, SD=12.9), with median follow-up time of 3.6 years and a median of 6 measurements per patient. Overall, HGB and ARC decreased across the lifespan; however, trends were moderated by genotype. Compared to individuals with non-severe genotypes, those with the severe genotypes had consistently lower HGB levels that did not differ by age. For ARC, the severe genotypes had higher levels in young adulthood, which slowly decreased with age. WBC also decreased with age for this group. In contrast, individuals with the non-severe genotype showed an increase in WBC by age. Platelet counts decreased with increasing age for those with the severe genotype while those with non-severe genotypes showed an increase with age. Conclusion Severe SCD genotypes are associated with decreases in HGB, ARC, WBC, and platelet count by age. For HGB and ARC, these declines are significantly attenuated by renal function, suggesting that such declines are largely related to worsening renal function with age. However, an intrinsic bone marrow contribution to this aging process should also be explored in future studies. Decreases in WBC and platelet count with time, observed in the severe genotypes, support the presence of pathological processes of bone marrow dysfunction that may worsen with age. A possible etiology of the increasing bone marrow dysfunction in SCD may be a result of bone marrow exhaustion or cellular senescence. Prospective studies to explore contributors to reduced blood counts during the aging process in individuals with SCD are needed. We are actively exploring potential biomarkers associated with this process. Figure 1 Figure 1. Disclosures Carden: Forma Therapeutics: Current Employment. Derebail: Novartis: Consultancy; UpToDate: Patents & Royalties; Travere Therapeutics: Consultancy; Bayer: Consultancy. Ataga: Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Consultancy; Forma Therapeutics: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Introduction:Chronic kidney disease (CKD) is common in sickle cell disease (SCD). We have recently reported on the progression of CKD in SCD and factors associated with it (Ciccone EJ et al, ASH, 2016). The purpose of this study was to evaluate the prevalence of rapid decline in kidney function, factors associated with such decline, and the association of rapid decline in kidney function with mortality in adult patients with SCD. Methods: We conducted a retrospective study of patients seen between July 2004 and December 2013 at an adult Sickle Cell Clinic. Patients had confirmed diagnoses of SCD, were at least 18 years old, and were in non-crisis state. We excluded patients with histories of HIV, hepatitis B and C, or systemic lupus erythematosus. Clinical and laboratory variables were obtained from medical records. Estimated glomerular filtration rate (eGFR) was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation. Rapid decline of kidney function was defined as eGFR loss of >3.0 ml/min/1.73 m2per year during the observation period. Logistic regression was used to model the association of rapid eGFR decline with clinical and laboratory variables, adjusting for age and sex. Multivariable analysis with variable selection was performed with backward elimination from the following initial variables - hemoglobin, reticulocyte count, lactate dehydrogenase, baseline eGFR, history of stroke, hydroxyurea therapy, systolic blood pressure, use of ACE inhibitors/angiotensin receptor blockers (ACE-I/ARB) and history of diabetes. Since proteinuria measures were missing for many patients, we performed sensitivity analyses with 1) exclusion of proteinuria, 2) inclusion of only patients with available values, 3) assignment of no proteinuria to those missing values, or 4) assignment of proteinuria to those missing values. Age- and sex- adjusted Cox proportional hazards models were used to evaluate the association of the slope of eGFR (continuous variable) or rapid decline in eGFR (binary variable) with mortality. The slope of eGFR was estimated by linear regression modeling of eGFR over time. Kaplan-Meier estimates of survival probabilities for rapid and non-rapid decline groups were obtained, and the log-rank test was used to compare the survival probabilities for the two groups. Results: Three hundred and thirty-one SCD patients with at least two eGFR measurements(SS = 218, SC = 67, Sβ0= 18, Sβ+= 22, SE = 2, SD = 2, SHPFH = 2), median age of 29 years (IQR: 20 - 41 years) were evaluated and followed for a median of 4.01 years (IQR: 1.66, 7.19). Rapid decline of eGFR (>3.0 ml/min/1.73 m2per year) was noted in 103 (31.1%) patients; 80 (33.9%) with severe genotype (HbSS/HbSβ0thalassemia) and 21 (23.6%) with mild genotype (HbSC/HbSβ+thalassemia).Baseline laboratory factors significantly associated with rapid decline in eGFR were hemoglobin (p = 0.007), ferritin (p = 0.01), and baseline eGFR (p = 0.01) (Table 1). There was a trend towards an association (p = 0.06) with baseline proteinuria (at least 1+ on dipstick urinalysis). Clinical variables significantly associated with eGFR decline were history of stroke (p = 0.002) and use of ACE-I/ARB (p = 0.006). In multivariable analysis, history of stroke (estimate: 1.07, p = 0.01) and use of ACE-I/ARB (estimate: 1.15, p = 0.01) were associated with rapid eGFR decline when proteinuria was excluded from the model or proteinuria status was assigned to those with missing values. When we limited the dataset to those with available values for proteinuria, only history of stroke (estimate: 2.00, p = 0.007) was associated with rapid decline in eGFR. Finally, we observed an association of the slope of eGFR change over time with mortality (hazard ratio [HR]: 0.99, p = 0.0002). Rapid decline in eGFR was significantly associated with increased mortality compared with eGFR decline of ≤ 3 ml/min/1.73 m2per year (HR: 2.40, p = 0.005). Kaplan-Meier estimates also showed significantly lower survival probabilities for patients with rapid eGFR decline (log-rank test; p = 0.0002) (Figure 1). Conclusion:Rapid decline in eGFR is common in SCD. Use of ACE-I/ARB and history of stroke are associated with rapid decline in renal function. Rapid decline in eGFR is associated with an increased risk of death in SCD. Long-term studies are required to determine if therapies that may reduce loss of kidney function may decrease mortality in SCD. Disclosures Ataga: Pfizer: Research Funding; Bioverativ: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals: Honoraria; Modus Therapeutics: Honoraria; Global Blood Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Introduction: Chronic kidney disease (CKD) is common in patients with sickle cell disease (SCD). Despite current practice and recent NHLBI guidelines, which recommend screening and treatment for albuminuria, the progression of CKD in SCD and factors associated with such progression remain poorly defined. The purpose of this study was to evaluate the prevalence of CKD and its rate of progression in adult SCD patients. We also evaluated the laboratory and clinical factors associated with CKD progression. Methods: We conducted a retrospective study of patients seen between July 2004 and December 2013 at an adult Sickle Cell Clinic. Patients had confirmed diagnoses of SCD, were at least 18 years old, and were in the non-crisis state at the time of evaluation. Patients were excluded for histories of HIV, hepatitis B and C, and systemic lupuserythematosus. Clinical and laboratory variables were obtained from medical records. Estimated glomerular filtration rate (eGFR) was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation.Presence of CKD was assessed by using a modification of the Kidney Disease Improving Global Outcomes clinical practice guidelines that incorporateseGFR and levels of albuminuria. CKD was defined aseGFR Results: Four hundred and twenty six patients with SCD (SS = 268, SC = 98, Sb0 = 22, Sb+ = 29, SE = 3, SD = 2, SHPFH = 4), median age of 29.5 years (IQR: 20 - 41 years), were evaluated. CKD at baseline was observed in 92 patients (21.6 %). The rate of decline in eGFR over time was 2.1 mL/min per 1.73 m2 per year (SE: 0.11, p < 0.0001) (Figure 1). Baseline laboratory factors that were significantly associated with decline ineGFR inunivariate analyses were hemoglobin, lactate dehydrogenase, indirect bilirubin, ferritin, hematuria, urine specific gravity, and proteinuria (at least 1+ on dipstick urinalysis). Clinical variables significantly associated witheGFR decline inunivariate analyses were weight, history of acute chest syndrome,history of stroke, chronic transfusion, systolic blood pressure, diastolic blood pressure, and use of ACE inhibitors/angiotensin receptor blockers (ACE-I/ARB). Multivariable analyses showed that the rate ofeGFR decline was dependent on the status of having proteinuria (estimate: -3.96, p < 0.0001), age (estimate: -0.05, p Conclusion: eGFR declined at a rate of 2.1 mL/min per 1.73 m2 per year in adult patients with SCD. Proteinuria, age, acute chest syndrome, stroke, and higher systolic blood pressure were associated with an increased rate of decline in eGFR. However, heavier weight and chronic red cell transfusions were associated with less severe eGFR decline. Better understanding of these relationships and their pathophysiology is needed so that we can modify identified risk factors and attenuate the loss of kidney function in SCD. Disclosures No relevant conflicts of interest to declare.