Myasthenia gravis following initiation of statin therapy: multinational selfcontrolled case series study

Abstract

<p>Introduction<br>Recently, regulatory authorities worldwide have advised patients receiving statins to be aware of the<br>potential onset of myasthenia gravis (MG) symptoms. Yet, evidence regarding this potential adverse<br>effect were limited to case reports and disproportionality analyses.<br>Aims<br>This study aims to examine the risk of incident MG following initiation of statin therapy using<br>multinational real-world data.<br>Methods<br>A self-controlled case series (SCCS) study was conducted using electronic medical records and claims<br>databases from Hong Kong, Japan, and United Kingdom. Individuals aged 18 years and above with<br>their first diagnosis of MG and first prescription of any statin during the study period were included.<br>Conditional Poisson regression was employed for within-individual comparison of MG risks during<br>different risk periods (up to two years after statin initiation) compared to the non-exposure period,<br>adjusted for age. Pooled results based on meta-analysis of all study sites were reported.<br>Results<br>A total of 2267 MG cases were analysed. Combining all study sites, we observed a significantly<br>increased risk of incident MG during the first year after statin initiation compared to the nonexposure<br>period, with a higher risk during days 0-179 (pooled IRR [95% CI]: 2.662 [1.276-5.553]) than<br>days 180-364 (1.407 [1.014-1.954]). No increased risk of MG was observed m -195- ore than one year after statin initiation (1.011 [0.848-1.206]). Moreover, the magnitude of MG risk elevation during first 180<br>days after statin initiation was more pronounced with higher intensity of statins used.<br>Discussion<br>In this multinational SCCS study, an increased risk of incident MG during the first 6-12 months after<br>initiation of statin therapy was observed, with greater magnitude of risk elevation for higher intensity<br>statin regimens. Monitoring for incident MG shall be warranted within the first 6-12 months after<br>initiating statin treatment, especially for medium-to-high intensity statin therapy.<br></p>