Understanding Flares in Patients With Generalized Pustular Psoriasis Documented in US Electronic Health Records

IMPORTANCE: Other than single-center case studies, little is known about generalized pustular psoriasis (GPP) flares. OBJECTIVE: To assess GPP flares and their treatment, as well as differences between patients with and patients without flares documented in US electronic health records (EHRs). DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study included adult patients with GPP (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision code L40.1) identified in Optum deidentified EHR data between July 1, 2015, and June 30, 2020. The index GPP diagnosis was the first occurrence in the EHR, with no coded history of GPP for at least 6 months prior. Flare episodes were identified using an algorithm based on diagnosis coding, care setting, type of clinician, GPP disease terms, and flare terms and attributes in the EHR. MAIN OUTCOMES AND MEASURES: Flare episodes were characterized by the frequency of occurrence per patient, the care setting in which they were identified, the type of specialist managing the episode, associated symptoms, and the type of treatment before, during, and after the episode. Patients were divided into groups based on whether or not they had a flare episode documented in their EHR. Comparisons were made between the groups based on demographic characteristics, comorbidity burden, health care use, and treatments. RESULTS: Of 1535 patients with GPP (1018 women [66.3%]; mean [SD] age, 53.4 [14.7] years), 271 had 513 flares documented. Compared with patients without flares, patients with flares had a 34% higher mean (SD) Charlson Comorbidity Index score (2.80 [3.11] vs 2.09 [2.52]), were almost 3 times more likely to have inpatient visits (119 of 271 [44%] vs 194 of 1264 [15%]), were more than twice as likely to have emergency department (ED) visits (126 of 271 [47%] vs 299 of 1264 [24%]), and had higher use of almost all treatment classes. Flares were identified in outpatient (271 of 513 [53%]), inpatient (186 of 513 [36%]), and ED (48 of 513 [9%]) settings. The most common treatments during flares were topical corticosteroids (35% of episodes [178 of 513]), opioids (21% [106 of 513]), other oral treatments, (eg, methotrexate, cyclosporine, tacrolimus; 13% [67 of 513]), and oral corticosteroids (11% [54 of 513]). Almost one-fourth of flare episodes (24% [122 of 513]) had no dermatologic treatment 30 days before, during, or 30 days after a flare episode. CONCLUSIONS AND RELEVANCE: This cohor