Idiopathic inflammatory myopathies (IIM) such as polymyositis, dermatomyositis, inclusion body myositis and immune-mediated necrotising myopathy, have a significant impact on health-related quality of life and work productivity.

A South Australian study comprised 50 patients with a mean age of 62 years and a mean duration of IIM of five years.

The unemployment rate in the group was a high 68% with consequences for lower HR-QOL in the physical component summary (PCS) and across domains of physical function and physical role limitations.

“Among the employed cohort, there were impacts of IIM on work productivity, with an overall median work impairment of 20.8% (IQR 10, 50).”

The study, published in the International Journal of Rheumatic Diseases, also found significantly lower SF-36 scores in seven of the eight domains when compared against Australian population norms.

While the PCS was lower in people with IIM, patients had similar scores to the general population in the mental component summary (MCS).

This suggested that despite significant physical impairments, patients with IIM had relatively well preserved emotional health.

Manual muscle strength testing (MMT-8) was positively associated with most SF-36 domains and inversely associated with work productivity life impairment.

“This supports the clinical utility of testing MMT-8; furthermore, targeted therapies to restore muscle power, such as immunomodulatory therapies and resistance training programs, should have a significant impact on HRQOL,” the study said.

Patient Global Activity Assessments showed patients who perceived their disease as more active also had poorer quality of life.

The study found no differences in HR-QOL between the different subtypes of IIM or in the duration of IIM or creatine kinase levels which are considered surrogate markers for disease severity.

“The findings of this study should be a reminder to treating clinicians of the far-reaching and diverse effects of IIM on patients’ HR-QOL and WP, and to encompass a multidisciplinary and holistic approach to address the impacts of IIM,” they concluded.