Current Prevalence of Specific Clinical Outcomes in Adult Patients with Hb SS or Hb Sβ⁰ Thalassemia.

Over the last five years, we have enrolled 541 unrelated adult patients (age >18) with HbSS or HbSβ⁰ at three major comprehensive sickle cell centers in a study designed to identify factors associated with clinical outcomes in sickle cell disease. Our database includes demographic, clinical, and laboratory data on all participants. Medical history was obtained by both patient interview and review of medical records. The average age of patients enrolled was 34.0 yrs, median age 31.9, and 61 were ≥ 50 yrs; 54% were female. 81% of patients had finished high school, and 35% smoked tobacco products. History of SCD-related complications was as follows: acute chest syndrome - 76%, priapism (males only) - 41%, stroke - 16%, TIA - 5%, seizure - 12%, AVN of shoulders or hips - 30%, leg ulcers - 26%, heart failure - 7%, gallstones - 66%, and retinopathy - 22%. 68% of patients had undergone cholecystectomy, 11% splenectomy, and 11% major joint replacement. 136 patients had echocardiography data reported, and of these 39% had findings consistent with pulmonary hypertension, as defined as TRjet ≥ 2.5 m/s. 7% were receiving chronic transfusion therapy, and 6% were receiving iron chelation therapy. Significant proteinuria (≥ 1+) was present in 27% of patients, while only 4% had hematuria. Review of medication usage revealed that 40% were taking hydroxyurea (HU) at the time of enrollment, and 23% used long-acting narcotics daily. 14% of patients took medication for hypertension, 9% took antidepressants, and 6% used bronchodilators. Interviews and review of records showed that 21% had not required hospitalization during the past year, while 25% were hospitalized only once, 46% were hospitalized 2–4 times, and 8% were hospitalized >4 times during the past year. Hematologic values and HU status were available for 433 patients.

Patients not on HU had significantly higher total bilirubin values (3.51±2.66 vs 2.91±2.93, p=0.02) and insignificantly higher ferritin levels (1297±2118 vs 1089±1535, p=0.5). However, patients taking HU had higher LDH (p=0.0019) and uric acid levels (p<0.0001). In summary, despite frequent use of HU, resulting in statistically higher hemoglobin levels and lower WBC, the prevalence of end-organ complications associated with SCD remains high. More than half of all patients were hospitalized at least twice annually, and almost one-quarter required daily long-acting narcotics. 30% of patients have AVN, and more than 10% of patients had already undergone major joint surgery. Further research into HU prescribing patterns and patient compliance might lead to improvement in patient outcomes, but other interventions are likely to be required in order to ameliorate the persistently high complication rate of SCD.