All-cause mortality in statin-associated immune-mediated necrotizing myopathy compared with idiopathic inflammatory myopathy
Oluoma M Edeh, Tam N Dinh, Maheswari Muruganandam, Frank X O’Sullivan, Avinash Sahu, Wilmer L SibbittAbstract
Objectives
Statin-associated immune-mediated necrotizing myopathy (IMNM) is a distinct idiopathic inflammatory myopathy (IIM) associated with anti–3-hydroxy-3-methylglutaryl–coenzyme A reductase (anti-HMGCR) antibodies. The present study determined all-cause mortality among patients with statin-associated IMNM.
Methods
In this retrospective cohort study of 142 adult patients with IIM evaluated at a tertiary academic medical center, statin-associated IMNM was defined by IMNM with recent statin exposure. IIM was defined by standard criteria. The primary outcome was all-cause mortality. Age-adjusted Cox proportional hazards models were the primary analyses with additional adjustments for age, diabetes mellitus, and hyperlipidemia with propensity score–weighted Cox models.
Results
Among 142 patients with IIM, 41 were statin-associated IMNM who were older and had shorter disease duration (p < 0.05). All-cause mortality was higher in statin-associated IMNM (31.7%, 13/41) than in IIM (23.8%, 24/101) (unadjusted HR 2.55, 95% CI 1.24–5.24; p = 0.011), with cardiopulmonary events and infections the major causes of death. In unadjusted analysis, statin-associated IMNM was associated with higher mortality (hazard ratio [HR] 2.55, 95% CI 1.24–5.24) and attenuated after age adjustment (HR 1.98, 95% CI 0.97–4.03) and was no longer statistically significant after adjustment for diabetes and hyperlipidemia (HR 1.70, 95% CI 0.71–4.08). Joint stratification by anti-HMGCR status and age (cutoff 60 years) demonstrated that older patients with statin-associated IMNM had the lowest survival among the four strata (log-rank P = 0.036).
Conclusions
Statin-associated IMNM is associated with higher mortality than other myositis subtypes; this excess attenuates after adjustment for age and cardiometabolic comorbidity, indicating these pre-existing conditions identify a higher-risk clinical phenotype.