Survival estimates of adults with sickle cell disease (SCD) in highincome countries are limited because of the absence of prospective cohorts of young adolescents followed to and through adulthood. Recently, Gardner et al described a cohort of 712 adults with SCD (16-80 years of age) at King's College Hospital (London, U.K.) from 2004 to 2013 that included 5268 patientyears of observation, and the median observation per patient was 8 years. 1 The estimated median age of survival was 67 years for 450 adults with HbSS/HbSb 0 , an age that is significantly greater than that observed in a similar study in the United States reporting a median survival of 44.7 years for 132 adults with HbSS/HbSb 0 /HbSD. 2

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Chronic end-organ complications result in morbidity and mortality in adults with sickle cell disease (SCD). In a retrospective-prospective cohort of 150 adults with SCD who received standard care screening for pulmonary function abnormalities, cardiac disease, and renal assessment from January 2003 to 2016, we tested the hypothesis that clustering of end-organ disease is common and multiple organ impairment predicts mortality. Any end-organ disease occurred in 59.3% of individuals, and 24.0% developed multiple organ (>1) end-organ disease. The number of end-organs affected was associated with mortality (P ≤ .001); 8.2% (5 of 61) of individuals with no affected end-organ, 9.4% (5 of 53) of those with 1 affected organ, 20.7% (6 of 29) of those with 2 affected end-organs, and 85.7% (6 of 7) with 3 affected end-organs died over a median follow up period of 8.7 (interquartile range 3.5-11.4) years. Of the 22 individuals who died, 77.3% had evidence of any SCD-related end-organ impairment, and this was the primary or secondary cause of death in 45.0%. SCD-related chronic impairment in multiple organs, and its association with mortality, highlights the need to understand the common mechanisms underlying chronic end-organ damage in SCD, and the urgent need to develop interventions to prevent irreversible end-organ complications in SCD.

Current definitions of acute chest syndrome (ACS) in sickle cell anemia (SCA) do not account for rapid progression of respiratory compromise. In this two-center retrospective cohort study, we tested the hypothesis that in children and adults with ACS and respiratory failure (≤24 hours after onset of respiratory symptoms) have a distinct ACS phenotype associated with multiorgan failure when compared to those with ACS that have a more subacute and protracted course. We identified 173 individuals (97 children <20 years and 76 adults ≥20 years) with SCA and at least one episode of ACS. Only one ACS episode was considered per individual. Rapidly progressive ACS occurred in 21% (n = 16) of adults, but only 2.1% (n = 2) of children. Compared to adults without rapidly progressive ACS, adults with rapidly progressive ACS more frequently developed acute kidney injury (68.8% vs. 3.3%, P < 0.001), hepatic dysfunction (75.0% vs. 15.0%, P < 0.001), altered mental status (43.8% vs. 11.7%, P < 0.001), multiorgan failure (93.8% vs. 10%, P < 0.001), and death (6.3% vs. 0%, P = 0.05). Clinical and laboratory covariates that were evaluable on the first day of respiratory symptoms were evaluated to identify predictors of rapidly progressive ACS. On multivariable analysis, decline in platelet count at presentation was the only predictor of rapidly progressive ACS [odds ratio 4.82 (95% CI 1.20-19.39), P = 0.027]. In conclusion, rapidly progressive ACS is a distinct phenotype that occurs more frequently in adults, is preceded by thrombocytopenia, and is associated with multiorgan failure. Am. J. Hematol. 91:1185-1190, 2016. © 2016 Wiley Periodicals, Inc.