Clinical spectrum of inflammatory myositis in South India--a ten year study

To describe the clinical spectrum of inflammatory myopathies at a referral hospital in South India.

Patients were assessed for the pattern of muscle involvement, for the presence of arthritis, Raynaud's phenomenon, interstitial lung disease (ILD) and cardiac involvement. Muscle enzymes, electromyogram (EMG) and muscle biopsies were done.

Eighty seven patients with inflammatory myopathies were encountered over 10 years. These included 24 with adult polymyositis, 26 with adult dermatomyositis, one with amyopathic dermatomyositis, five with juvenile myositis, one with dermatomysitis following carcinoma breast and 30 with overlap with other connective tissue diseases. There was a female preponderance (M:F = 1:2.35) except in juvenile myosits group (M:F = 1.5:1). The mean age of onset in years was 33.26 in adult polymyositis, 35.03 in adult dermatomyositis, 7.4 in juvenile dermatomyositis, 42 in malignancy-associated dermatomyositis and 25.51 in the overlap group. Proximal muscle weakness was seen in 98.8% patients, dysphagia in 33.3%, distal muscle weakness in 12.5%, respiratory muscle weakness in 9.2% and dysphonia in 4.6%. Other features included arthritis 35.63%, interstitial lung disease (ILD) 9.2%, Raynaud's 5.7%, myocarditis 4.6% and conduction disturbances 1.15%. Eleveated muscle enzymes were seen in 85.1% patients. Eletromyogram was positive in 66.6%. Muscle biopsy was positive in 85.29%. Anti-nuclear antibody was positive in 67.24%. All received steroids, non-responders needed methotrexate (13 patients) or azathioprine (11 patients). Death occurred in 10 (seven with dermatomyositis predominantly due to respiratory involvement and three with overlap).

There was female preponderance except in juvenile myositis group. Proximal muscle weakness was the commonest feature. ILD was the commonest respiratory problem, while myocarditis was the commonest cardiac problem seen. Response to therapy and prognosis in polymyositis were good with no mortality during the study period. Death in the dermatomyositis group was mainly due to respiratory involvement.