What determines quality of life in inclusion body myositis?

Background: Quality of life (QoL) assessment allows healthcare professionals to appreciate the patient perspective of their disease. This can help us make a better choice from among the various ways we currently measure the severity of a muscle disease such as inclusion body myositis (IBM). However, we cannot assume that QoL in IBM is just related to disease severity as psychosocial factors may play an important role in determining QoL. Methods: Sixty subjects with IBM had assessments of disease severity and concurrent assessment of mood and QoL using the Short-Form 36 (SF-36). Results: There were significant reductions in Physical functioning, Role physical, General health and Social functioning domains of the SF-36. Functional disability was more indicative of the broader effects of IBM on SF-36 than was the muscle strength sum score. Mood was relatively independent of disease severity and had a different profile of effects on SF-36 domains. Up to 14% of the effect of functional disability on some aspects of QoL was mediated through mood. Conclusions: The functional disability caused by IBM reduces QoL, but psychosocial factors such as mood affect QoL directly and by influencing the degree to which disease severity reduces QoL. Further study should follow the effects of IBM on QoL over time and look at the influence of other psychosocial factors. Such studies may point to psychosocial interventions that may help improve QoL in IBM even if the disease itself cannot be treated.