Acute painful episodes and acute chest syndromes are common complications of sickle cell disease (SCD), often leading to emergency department (ED) visits. ED utilization differs among patients with SCD and varies over time for most individual. Factors such as genotype, age, sex, medication adherence, previous SCD complications, psychiatric comorbidities, and meteorological conditions have been suggested as contributors to this variability. This study aims to identify the main patterns of ED utilization in adults with SCD, and describe associated factors.

We analyzed data from all adults with SCD followed up at a French reference center and hospitalized at least once between October 1, 2013 and December 31, 2019. We used a Cox model for recurrent events with fixed and time dependent variables to estimate (i) the cumulative risk of ED visits and (ii) its variability over time. We then applied clustering methods on these two dimensions to identify typical patterns of ED utilization and compared the characteristics of individuals across these patterns.

We included 656 adults with SCD, accounting for 9,080 ED visits over a median follow-up of 5 years (interquartile range [IQR] 3–6), corresponding to 1 ED visit per patient per year (IQR 1–3). Of these visits, 5,157 (57%) resulted in home discharge, 3,573 (39%) led to hospital admission, and 350 (4%) required transfer to the intensive care unit.

Two clusters of patients emerged, based on their ED utilization: 529 (81%) with low ED use, accounting for 2,924 ED visits (32%); 127 (19%) with high ED use, accounting for 6,156 ED visits (68%). Patients in the high-use group had a higher prevalence of usual risk factors for ED visit, such as younger age, SS/Sβ0 genotype or past acute chest syndrome. They also had a significantly higher prevalence of psychiatric comorbidities (56% vs. 14%, P<0.001), notably anxious disorders (40% vs. 6%, P<0.001).

All individuals in the high-use group experienced bursts of ED visits, defined as at least 3 visits within 3 months and at least 3 times more than during the previous 3 months. This burst pattern was uncommon in the low-use group (7% of patients). Among patient prone to bursts, ED visits spaced less than a month apart were followed by a significantly increased risk of a new ED visit within the next month (adjusted hazard ratio 3.49 [95%CI 2.95–4.06]).

Our findings highlight two main patterns of ED utilization in adults with SCD, with a small subset of patients (19%) accounting for more than two thirds of ED visits (68%). These high-use patients have a markedly higher prevalence of psychiatric comorbidities and frequently experience bursts of ED visits, which strongly predict subsequent visits in the short term. These findings underscore the importance of integrating psychiatric support into SCD care and closely monitoring patients during burst period, to prevent recurrent ED visits.

Better understanding the factors that trigger bursts of ED visits in adults with SCD may lead to targeted interventions, such as mental health support, aimed at reducing ED utilization and improving patient outcomes and experience.