Influence of colchicine prescription in COVID-19-related hospital admissions: a survival analysis

Aims: To analyze the association between colchicine prescription and COVID-19-related hospital admissions in patients with rheumatic and musculoskeletal diseases (RMDs). Methods: Patients attending a rheumatology outpatient clinic from a tertiary care center in Madrid, Spain, from 1 September 2019 to 29 February 2020 were included. Patients were assigned as exposed or unexposed based on whether they were prescribed with colchicine in their last visit to the clinic during the 6 months before the start of the observation period. Treatment changes during the observation period were also considered. The primary outcome was COVID-19-related hospital admissions between 1 March and 20 May 2020. Secondary outcome included COVID-19-related mortality. Several weighting techniques for data balancing, based and non-based on the propensity score, followed by Cox regressions were performed to estimate the association of colchicine prescription on both outcomes. Discussion: The number of patients entered in the study was 9379, with 406 and 9002 exposed and unexposed follow-up periods, respectively. Generalized Boosted Models (GBMs) and Empirical Balancing Calibration Weighting (EBCW) methods showed the best balance for COVID-19-related hospital admissions. Colchicine prescription did not show a statistically significant association after covariable balancing ( p-value = 0.195 and 0.059 for GBM and EBCW, respectively). Regarding mortality, the low number of events prevented a success variable balancing and analysis. Conclusion: Colchicine prescription does not play a significant protective or risk role in RMD patients regarding COVID-19-related hospital admissions. Our observations could support the maintenance of colchicine prescription in those patients already being treated, as it is not associated with a worse prognosis. Plain language title: Colchicine influence in COVID-19-related hospital admissions