Risk of myasthenia gravis onset highest in first month after statin initiation

14 Dec 2024 bởiNatalia Reoutova
Risk of myasthenia gravis onset highest in first month after statin initiation

A study investigating the association between the risk of myasthenia gravis (MG) and statin therapy found the risk of onset in patients with no prior history of MG and the risk of exacerbation among patients with pre-existing MG were the highest in the first month after initiating statins.

“In 2023, several international pharmacovigilance organizations, including those in Europe, the UK, Australia, Japan, and Hong Kong, issued a warning about the risk of new-onset or worsening of pre-existing MG following statin therapy. [However,] there are limited studies examining this relationship,” wrote the researchers. “To support informed clinical decisions and provide specific guidance, our study applied two designs to investigate the risk of new-onset and exacerbation of MG following statin initiation, using a sequence of nested target trials emulation [TTE] for interpersonal comparison and self-control cases series [SCCS] for intrapersonal comparison based on real-world population-based electronic health records.” [Nat Commun 2024;15:10317]

Data were obtained from the Hong Kong Hospital Authority’s electronic health records of 369,850 statin initiators without pre-existing MG (average age, 6.2 years; male, 50.5 percent) and 112 initiators with pre-existing MG (average age, 62.3; male, 37.5 percent). Data for eligible patients were extracted from the database on a rolling basis in each calendar month from January 2009 to December 2016 and followed up until the outcome of interest, death, or the end of the 24th month after baseline, whichever occurred first.

In TTE, the incidence rate (IR) of MG onset for statin initiators was 51.91 per 100,000 person-years (PY) in month 1, 16.27 in months 2–4 and 15.27 in months 5–7. The IRs of MG onset among statin initiators during the subsequent 18 months were comparable to those who did not initiate statin therapy (<10/100,000 PY). The adjusted hazard ratios (HRs) for MG onset in intent-to-treat (ITT) analysis were 6.11 (95 percent confidence interval [CI], 3.73–10.01) in month 1, 1.92 (95 percent CI, 1.15–3.19) in months 2–4 and 1.80 (95 percent CI, 1.06–3.04) in months 5–7. No significantly increased risk was found during the following 18 months.

Similar results were found in the SCCS analysis, where the IR ratio of MG onset was 7.68 in the first month after statin initiation, 2.42 in months 2–4 and 2.33 in months 5–7. Among patients with pre-existing MG, the IR of exacerbation was also higher in month 1, months 2–4, and months 5–7, with adjusted HRs for exacerbation in ITT analysis of 10.69 (95 percent CI, 5.48–20.84) in month 1, 1.50 (95 percent CI, 0.55–4.06) in months 2–4, and 2.79 (95 percent CI, 1.33–5.84) in months 5–7. No increased risk for exacerbation was found in the following 18 months.

Significantly increased risks of MG onset and exacerbation were observed in most patient subgroups in the first 7 months after statin initiation, but not in the subsequent 18 months. “However, for patients aged <60 years, the HR for MG onset [1.27; 95 percent CI, 0.66–2.45] in the initial 7 months was not as high as for those aged >60 years [3.24; 95 percent CI, 2.33–4.52; pinteraction=0.012] in the same time period,” noted the researchers.

“Significantly increased risks of MG onset and exacerbation of pre-existing MG observed in the first months following statin initiation suggest a minimum monitoring period for MG symptoms of approximately 6 months in patients initiating statins, irrespective of pre-existing MG,” advised the researchers.