Polypharmacy, drug-drug interactions, and adverse drug reactions among systemic sclerosis patients: A cross-sectional risk factor study.

Objectives: Polypharmacy, drug -drug interactions (DDI) and related adverse drug reaction (ADR) are understudied in SSc. The aim of this work was to determine the prevalence and determinants of DDI and ADR in a reallife prospective cohort of SSc patients. Methods: We performed a retrospective analysis of the drug prescriptions of SSc patients admitted to the daily scleroderma clinic between January 2020 and April 2022. DDI were identified using 2 prescription analysis applications, and adjudicated related ADRs occurring during a one-year follow-up were reported. Risk factors for DDI and ADR were identified using multivariate analysis. Results: One hundred and eight SSc patients were included. The median number of medications per patient was 6 [4 -9]. Seventy-one (65.7 %) patients had 5 or more medications, and 23 (21.3 %) had 10 or more. Seventy-two (66.7 %) patients had DDIs on their prescriptions at inclusion. Patients with DDIs had more medications than patients without DDIs (7 [5 -10] versus 3 [2 -5], p < 0.0001). Six (8.3) patients experienced ADRs during the oneyear follow-up. Patients with ADRs had more medications (14 [10 -18] versus 7 [5 -10] p < 0.001) and more DDIs (12 [7 -32] versus 3 [1 -6]; p < 0.001) than patients without ADRs. Multivariate analysis confirmed that the number of prescribed medications was independently positively associated with DDIs (OR: 2.25 [1.52 -3.32], p < 0.0001) as well as with ADRs (OR: 1.68 [1.17 -2.40], p < 0.01). Conclusions: SSc patients are significantly exposed to polypharmacy, DDIs and related ADRs, particularly in cases of severe illness, and especially if 5 or more medications are prescribed.