Potentially inappropriate drug use in myasthenia gravis: a real-world population-based cohort study in Italy

Abstract

IntroductionTo evaluate the use of pyridostigmine in presence of contraindications, and the use of concomitant potentially contraindicated drugs in a cohort of patients affected by Myasthenia Gravis (MG) in the Italian Regions of Lazio, Tuscany, and Umbria.MethodsThis is a retrospective cohort study. A multivariate logistic regression model was used to evaluate the determinants of pyridostigmine and of potentially contraindicated drugs use in MG patients.ResultsAmong 591 incident pyridostigmine users affected by MG, 91 (15.4%) had at least one of the contraindications considered at the first prescription of pyridostigmine. Patients prescribed with pyridostigmine in presence of contraindications were more frequently affected by diabetes, obesity, and renal diseases. Age 75+ years (odds ratio, OR 4.94, 95% confidence interval, CI 1.60–15.22 for Latium; OR 3.78, 95%CI: 1.26–11.34 for Tuscany; OR 5.83, 95%CI 1.19–28.52 for Umbria), the presence of at least one specific comorbidity (OR 3.93; 95%CI 1.68–9.17 for Latium), and polytherapy (6+ drugs, OR 4.90, 95%CI: 1.35–17.85 for Tuscany) were found to be significantly associated with pyridostigmine use in presence of contraindications. Among patients affected by MG, 1,483 (62.6%) were treated with potentially contraindicated drugs in the first year of follow-up (67.06.9% in Latium; 59% in Tuscany; 57.6% in Umbria). Patients aged 75+ years, those with at least one specific complication or comorbidity, and those exposed to polytherapy were more likely to be treated with a potential contraindicated drug.ConclusionAmong incident users of pyridostigmine, more than 15% of patients have at least one of the contraindications considered, and among patients diagnosed with MG, in the first year of follow-up >60% of subjects were treated with potentially contraindicated drugs.

Drug Use Patterns in Myasthenia Gravis: A Real-World Population-Based Cohort Study in Italy

“…Moreover, it is to be taken into account that our enrolment date may not be the true start of the disease. Of notice, these limitations may have different impacts in the three regions, because traceability of drug claims depends on the administrative procedures underlying drug registration under different reimbursement policies [ 19 , 20 , 33 ]. Furthermore, treatments administered to in-patients (immunomodulation therapies such as intravenous immunoglobulins and plasma exchange) and self-prescribed drugs (i.e., over-the-counter medications) are generally not retrievable at the patient level.…”

“…This is a real-world population-based retrospective cohort study, part of a multiregional Italian pharmacovigilance project on the comparative effectiveness and safety of drugs used in rare neuromuscular and neurodegenerative diseases (the CAESAR project) [ 19 , 20 ]. In the period 2013–2019, three Italian regions were involved: Latium, Tuscany, and Umbria.…”