Association of statin exposure with histologically confirmed idiopathic inflammatory myositis

A population-based case-control study examined the association between current exposure to statin medications and histologically confirmed idiopathic inflammatory myositis (IIM). The group of rare, clinically heterogeneous, autoimmune muscular disorders can lead to permanent disability and death.

A population-based case-control study examined the association between current exposure to statin medications and histologically confirmed idiopathic inflammatory myositis (IIM). The group of rare, clinically heterogeneous, autoimmune muscular disorders can lead to permanent disability and death. For the study, researchers used the South Australian Myositis Database of all histologically confirmed IIM cases diagnosed between 1990 and 2014 among individuals aged 40 years or older and population-based controls from the North West Adelaide Health Study. At the time of IIM diagnosis, 68 of 221 (30.8%) patients had been exposed to statins, compared with 142 of 662 matched controls (21.5%). The likelihood of statin exposure among patients with IIM was nearly two-fold higher compared with controls. "While the incidence of IIM is rare (0.1 per 100,000 persons per year to 1.0 per 100,000 persons per year) and statin-associated autoimmune myopathy even rarer (estimated 2 per 1,000,000 persons per year), increasing use of statins at the population level, the severity of this condition, and the need for immunosuppressive treatment highlights the importance of early recognition of this disease," the researchers write. Although a causative role cannot be made from the observed association, the authors say the results point to the need for more research. Additionally, they suggest that "the potential risk of IIM should be considered in the assessment of risks and benefits of statin medications."