Assessing potential risk factors for metamizole-induced leukopenia.

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.

METHOD: We compared hospitalized patients treated with metamizole who developed leukopenia, with similar hospitalized patients who did not develop this side effect. RESULTS: It was observed that patients were more likely to develop leukopenia under metamizole therapy if they: - had previous episodes of leukopenia - were under cytostatic/immunosuppressive therapy (for example drugs used to treat cancer or autoimmune conditions) - had a history of penicillin allergy. CONCLUSION: These findings will help in identifying people who are at risk of developing this serious side effect, so that they can be given a medication for pain or fever that suits them better.

Assessing potential risk factors for metamizole-induced leukopenia Background: Metamizole is a medication used to treat pain and fever. It carries a risk of developing the side effect of a low white blood cell count (leukopenia). Researchers have identified certain risk factors which predispose some, but not all, people to develop this side effect. We undertook this study to examine these risk factors in more detail.