Abstract
BACKGROUND: Metamizole is a non-opioid analgesic agent that can rarely cause agranulocytosis, a severe form of leukopenia. OBJECTIVES: The aim of this study was to assess previously identified potential risk factors for the development of metamizole-induced leukopenia. DESIGN: A retrospective, observational, matched case-control study was performed in a single-center setting. METHODS: Patients who developed leukopenia in the setting of metamizole therapy were included as cases and matched 1:3 on the basis of age and sex to control patients who did not develop leukopenia when treated with metamizole. The data were obtained from the medical records of patients hospitalized at Cantonal Hospital Baselland between 2015 and 2020. Univariate and multivariate analyses were performed. RESULTS: Eighty-six cases and 258 matched controls aged between 18 and 102 years were included. Fifty-seven percent were female. Previous leukopenic episodes (odds ratio (OR): 4.02, 95% CI: 1.95-8.28, p < 0.001) and a history of penicillin allergy (OR: 2.49, 95% CI: 1.03-6.03, p = 0.044) were found to be independent risk factors for metamizole-induced leukopenia. CONCLUSION: A history of previous leukopenic episodes and a history of penicillin allergy were confirmed as risk factors for metamizole-induced leukopenia. In our opinion, metamizole should be avoided in patients with these risk factors.