Objectives: To estimate cost of a sickle cell (SC) crisis, describe setting of care, and type of crisis; and compare costs of sequential crises among adult SC patients. Methods: We used a large US health plan claims database 2 Truven Commercial & Medicare Supplemental. Patients selected had $2 SC claims, presence of SC crisis between 2009-2016 (i.e., SC crisis diagnosis in emergency department [ED] or hospitalization), age $18y at index (i.e., first crisis), 1-year pre-and post-index continuous enrollment, and no crisis during 1-year pre-index period. Healthcare setting, type of crisis, and medical and pharmacy costs during the crisis encounter were measured. Costs of sequential crises were restricted to patients with fee-for-service insurance, adjusted for 2017 inflation, controlled for age, gender and comorbidities, and were compared using gamma models. Results: There were 1,583 patients (1,234 fee-for-service), mean (SD) age 38y ( 14) and 58% female. Mean number of crises during 1-year post-index was 1.9. Average time between crises was 4.2 months. Number of patients with 1+, 2+, 3+ and 4+ crises within 1 year were 1,583 (100%), 679 (43%), 306 (19%) and 160 (10%), respectively. Among these, 52%, 55%, 59% and 61% were hospitalized for the 1st-4th crises (average length of stay: w7 days), and the rest had ED visits. After one crisis, patients tended to have the same setting of care for their next crisis. Across all crises, majority were pain crises (w63%), followed by acute chest syndrome (w11%). Mean (SE) adjusted costs of 1st-4th crises were $12,685
