Myasthenia gravis following statin therapy: evidence from target trial emulation and self-controlled case series study

Several international pharmacovigilance agencies have issued warnings regarding the potential risk of myasthenia gravis (MG) following statin therapy. Our study investigated this association using population-based electronic health records in Hong Kong. We conducted a sequence of target trial emulation (TTE) for interpersonal comparison and a self-controlled case series (SCCS) study for intrapersonal comparison. In the TTE for MG onset, the incidence rates (per 100,000 person-years) and adjusted HRs were 51.91(31.80, 84.74)[HR:6.11 (3.73, 10.01)] in month 1, 16.27(9.81, 26.99)[HR:1.92(1.15, 3.19) in months 2-4, and 15.27(9.05, 25.79)[HR:1.80(1.06, 3.04)] in months 5–7. For risk of exacerbation, the adjusted HRs were 10.69(5.48, 20.84) in month 1, 1.50(0.55, 4.06) in months 2–4, and 2.79(1.33, 5.84) in months 5–7. No increased risks were found during the subsequent 18 months. A similar pattern was observed in SCCS analysis. Our findings recommend a minimum monitoring period of approximately six months for MG symptoms for patients starting using statin. There is evidence of increased risk of myasthenia gravis following statin therapy. Here the authors investigated this association using electronic health records and suggest a minimum monitoring period of approximately six months for MG symptoms for patients starting using statins.