METHODS: Medical records of 254 SCD patients ≥16 years old were retrospectively reviewed at three US tertiary care centers. High utilizers (HUs) were defined as patients with ≥5 days of IP+ED care for SCD-related complications per year. Patients were classified in cohorts based on cumulative blood transfusion and iron chelation therapy (ICT): <15 units, no ICT (C1); ≥15 units, no ICT (C2); ≥15 units, with ICT (C3). SCD complication rates were expressed as the number of SCD complications per patient per year (PPPY); cohort comparisons used rate ratios (RRs). A logistic regression was used to identify risk factors for high IP+ED utilization.

RESULTS: Of 254 patients (C1: 69, C2: 91, C3: 94), 30% were HUs (C1: 14[18.4%], C2: 37[48.7%], C3: 25[32.9%]). HUs were younger (median [range]: 21 [16-65] vs. 23 [16-59] years old), and had shorter observation time (mean: 6.7 vs. 8.2 years). HUs accounted for 68% of SCD-related complications and 88% of IP+ED days. Pain (81%) and infection (7%) were key HU complications. Mean (95% CI) PPPY IP+ED days was higher among HUs (16.63 [16.28-16.99]) vs. other patients (0.89 [0.84-0.94]). Among regularly transfused HUs (C2+C3), those with ICT had fewer IP+ED days (C2 vs. C3 RR [95% CI]: 1.30 [1.24-1.36]) and IP+ED readmissions within 30 days (1.70 [1.49-1.93]). History of infections was associated with an increased risk of high IP+ED utilization (odds ratio: 7.45, p<0.0001). CONCLUSIONS: In this study of SCD patients a minority of patients accounted for a disproportionate share of IP+ED use. Frequently transfused patients without ICT had more IP+ED use than those with ICT. Identifying HUs can assist payers and providers in directing targeted interventions to deliver better care with lower costs.