Myopathy remains common among patients chronically treated with glucocorticoids

Key takeaways:

• 47.5% of patients treated with glucocorticoids reported myopathy.
• Cumulative dosage, age, sex and weight were contributing risk factors for glucocorticoid-induced myopathy.

Myopathy is a common side effect of systemic glucocorticoids for the treatment of autoimmune blistering disease and must be monitored by health care professionals, according to a study.

“Systemic glucocorticoids (GCs) have been the cornerstone of [autoimmune blistering disease (AIBD)] management since the 1950s,” Ailin He, of the department of dermatology at St. George Hospital and Faculty of Medicine at UNSW in Sydney, and colleagues wrote. “However, long-term GC exposure is common due to the persistent and recurrent disease course of AIBDs.”

GC-induced myopathy is a well-established side effect of GC treatment, which puts patients with AIBD at risk. As part of the first study to analyze GC-induced myopathy in patients with AIBDs, He and colleagues set out to investigate the nature, prevalence and risk factors of this side effect.

The international cohort study included 139 patients (mean age, 50 years; 77% women) with AIBD, divided into three groups: active GC treatment (n = 110), ceased GC treatment (n = 17) and controls (n = 12). Each patient was required to attend at least one baseline visit and two follow-up visits 3 months apart. At each visit, the Glucocorticoid Toxicity Index (GTI) was used to measure GC toxicity.

Results showed that a total of 132 episodes of myopathy occurred among these patients with 47.5% reporting muscle weakness at some point during the study. The majority of episodes were categorized as mild in severity; however, three were severe.

While the average dose and treatment duration were not significantly correlated to myopathy risk, the cumulative GC dose was. Age was a risk factor for myopathy with those aged 50 to 65 years being 2.39 (95% CI, 1.45-3.91) times more likely to develop myopathy vs. those aged younger than 50 years. Other risk factors including male sex (OR = 2.03; 95% CI, 1.27-3.24) and having a BMI above 30 kg/m² (OR = 2.64; 95% CI, 1.38-5.07).

“Cumulative dosage above 0.75 mg per day particularly in male patients older than 50 years old should be avoided,” the authors concluded, adding that exercise programs may also be a beneficial way to mitigate the effects of myopathy during GC treatment. “Overall, [myopathy] can cause significant morbidity and should be monitored throughout GC treatment to optimize management of AIBD patients.”