Prolonged Survival despite High Disease Burden in Elderly (≥55) Patients with Hb SS or Hb Sβ0 Thalassemia
Authors: Silbermins Damian , De Castro Laura M. , Ashley-Koch Allison E , Jonassaint Jude C , Garrett Melanie E. , Eckman James R. , Orringer Eugene P. , Telen Marilyn J. 
Published: October 2019

Abstract
In 1994, the average age of death of patients with sickle cell disease (SCD) in the US was 42 years for males and 48 for females. We theorized that patients who lived appreciably beyond these ages would therefore have lower disease burden than patients overall, and that lack of specific disease complications would be characteristic of such patients. From 2001 until 2006, we enrolled 541 unrelated adult patients (age ≥18) with Hb SS or Hb Sβ0 at three comprehensive sickle cell centers in a study designed to identify factors associated with clinical outcomes in SCD. Our database includes demographic, clinical, and laboratory data on all participants. We identified 61 patients 50 years and older and 32 patients 55 years and older. Among the latter, the average age was 60.6, with a median of 58 years (range 55–83); 65% were female. Although patients with SCD are generally thought to have a low prevalence of hypertension, the mean BP in this older cohort was 142/75, and 55% of patients were taking anti-hypertensives. Patients ≥55 had the following history of SCD-related complications: acute chest syndrome – 69%, priapism (males only) – 46%, stroke – 16%, TIA – 10%, seizure – 3%, AVN of shoulders or hips – 40%, leg ulcers – 38%, heart failure – 16%, gallstones – 64%, and retinopathy – 40%. Compared to all patients, elderly SCD patients had higher prevalence of TIA (10% vs 5%), retinopathy (40% vs 21%), and heart failure (16% vs 6%), and lower prevalence of seizures (3% vs 12%). When compared to younger patients, the elderly had a similar rate of AVN (40% vs 30%) but a significantly higher number had undergone surgical joint interventions (33% vs 10%; p=0.0001). The percentage of patients who had had cholecystectomies and splenectomies was uniform through the whole study cohort. Most interestingly, 60% of patients ≥ 55 had findings consistent with pulmonary hypertension, defined as TR jet ≥ 2.5 m/s on echocardiography. This represented approximately twice the prevalence seen in the entire study cohort. Significant proteinuria (≥ 1+) was present in 41% of patients, again approximately twice as frequently as seen in younger patients. Interviews and review of records showed that 47% of elderly patients had not required any hospitalizations during the past year (compared to only 27% in the total study cohort), while 20% were hospitalized only once, 20% were hospitalized 2–4 times, and 6% were hospitalized >4 times. Review of medication usage revealed that 35% were taking hydroxyurea (HU) at the time of enrollment, and 13% used long-acting narcotics daily (compared to 39% and 24% of the total cohort, respectively). When hematologic parameters were compared for elderly patients who were or were not taking HU, no significant differences were observed for Hb, Hct, WBC and platelet counts, although the mean Hb for patients taking or not taking HU were 8.5 and 7.8 g/dL respectively. We conclude that when compared to the overall population, the elderly had a higher prevalence of pulmonary hypertension, systemic hypertension, TIA and joint replacement, suggesting that contrary to our hypothesis, the degree to which they had experienced SCD-related end-organ damage was not decreased. While the frequency of HU use was similar to all patients, HU did not have clear effects on hematologic parameters in the elderly, raising the question of its efficacy in this population. Finally, the elderly did have some indicators of lower disease severity—namely, lower use of daily long-acting narcotics and fewer admissions for painful episodes. While research has traditionally focused on the high-risk SCD population, we believe that further investigation of elderly patients as a “lower risk” group is warranted to further advance our understanding of the relationship of SCD complications to survival.