Fatigue Closely Tracks Disease Activity in Myositis

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Fatigue Closely Tracks Disease Activity in Myositis

NEW findings reinforce that fatigue is not just a secondary symptom in myositis, but a central feature of disease activity that should be routinely assessed in both clinical care and research.

Idiopathic inflammatory myopathies (IIM), including dermatomyositis and polymyositis, are characterised by muscle inflammation and systemic involvement. However, patients frequently report fatigue as one of the most debilitating aspects of the disease, often impacting quality of life as much as physical symptoms.

Fatigue Affects the Majority of Patients

In this prospective observational study, 50 adults with myositis were followed over six months, with fatigue assessed using both a visual analogue scale and the SF-36 energy-fatigue domain.

The results showed that fatigue is highly prevalent, with 67% of patients reporting moderate to severe fatigue on the visual scale and over half showing similar levels on standardised measures.

Strong Link to Disease Activity

Crucially, fatigue was found to correlate closely with multiple indicators of disease activity. These included muscle involvement, extra-muscular manifestations, physician global assessments, pain, and physical function.

The association was consistent both at baseline and over time, indicating that fatigue reflects underlying disease processes rather than being an unrelated or purely subjective symptom.

Responsive to Clinical Improvement

One of the most important findings was that fatigue improved in parallel with reductions in disease activity. Patients who responded to treatment, based on established 2016 ACR/EULAR response criteria, also experienced meaningful reductions in fatigue.

This suggests that fatigue is not only measurable and reliable, but also sensitive to change, making it a useful marker for monitoring treatment response.

Implications for Practice and Trials

The study also demonstrated strong reliability and validity of fatigue assessment tools, supporting their use in both clinical and research settings.

Taken together, the findings argue for fatigue to be considered an integral component of myositis disease activity, rather than a secondary outcome. Incorporating fatigue into routine assessment could provide a more complete picture of patient burden and treatment effectiveness.

Looking Ahead

While the study size was relatively small, the consistency of findings strengthens the case for prioritising fatigue in myositis management.

Future research will need to explore targeted interventions for fatigue, but for now, the message is clear: if you ignore fatigue in myositis, you are missing a major part of the disease.

Reference

George TB et al. Fatigue is common in myositis and is associated with disease activity. Semin Arthritis Rheum. 2025;73:152730.

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