Small clinical trials have shown that concomitant immunomodulatory (IMM) drug use improves pegloticase persistence in the treatment of gout. However, real-world evidence has been lacking. Therefore, researchers evaluated pegloticase persistence and adverse events associated with concomitant IMM drug use in patients with uncontrolled gout. They conducted a retrospective cohort study and selected patients with procedure codes for pegloticase using ACR’s Rheumatology Informatics System for Effectiveness (RISE) registry from January 2016 to June 2020. Based on use of the concomitant IMM drug, the study team identified two exposure groups: 1) IMM users (defined as ≥ 1 IMM prescription within ±60 days of index); and 2) non-IMM users. They calculated the proportion of patients who ever achieved the serum urate (SU) ≤ 6mg/dL and patients who had lab abnormalities (WBC < 3.4; platelets < 135,000; hematocrit [HCT] < 30; ALT or AST ≥1.5X ULN) within 180 days after the index date. Time to pegloticase discontinuation was analyzed using a Cox regression model controlling for potential confounders including age, sex, race, BMI, national area deprivation index, concurrent medications, and number of RxRisk categories (a measure of comorbidity based on medications for specific diseases). Among pegloticase users, 700 had a median follow-up of 14 months; among them, 124 were IMM users and 576 non-users. During follow-up, 90% of patients ever met the SU treatment target. The median number of pegloticase infusions was seven for IMM drug users and five for non-users. Compared with non-users, IMM users were less likely to discontinue pegloticase. After adjustment, the HR for discontinuation of pegloticase associated with concomitant IMM therapy was 0.57.