Prognosis

Classic dermatomyositis

With treatment, prognosis has improved with 5-year survival of 95% and 10-year survival of 84%.[193] However, despite improved survival rates, one third of patients will experience permanent disability that can be severe.[194][195]

Although some patients have an acute illness and do not require long-term maintenance therapy, most experience a chronic disease with a relapsing-remitting course. Most patients require long-term treatment with corticosteroids or other immunosuppressant agents and many experience complications related to this.

Amyopathic dermatomyositis

Patients with clinically amyopathic DM may have subclinical evidence of muscle disease (hypomyopathic) or may be truly amyopathic, and often present early with cutaneous manifestations.

Response to treatment of subclinical muscle disease may be better as a result of early diagnosis and treatment or less severe myositis.[96] Cutaneous disease is often more resistant to treatment and can cause significant morbidity.[96]

Amyopathic patients require continued follow-up to screen for the development of muscle disease. In the absence of malignancy the prognosis is good.[196][197]

Prognostic indicators

Several factors are associated with a poorer outcome. These include:

  • Delay in treatment for >6 months after symptom onset[130][198]

  • Greater muscle weakness at presentation[199]

  • Respiratory muscle involvement[200]

  • Interstitial lung disease[194]

  • Malignancy[194]

  • Dysphagia[199]

  • Cardiac involvement.[200]

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