Effect of early treatment in polymyositis and dermatomyositis

Abstract

Background: Idiopathic inflammatory myopathies, dermatomyositis (DM) and polymyositis (PM) are rare but are potentially treatable.

Aim: To compare the effect of early and late treatment in patients with PM and DM.

Materials and methods: The study included all the adult patients with definite diagnosis of PM or DM treated for at least 12 months. The patients were divided into two groups: Early Group - treatment within three months and Late Group - treatment after three months. The number of patients with positive therapeutic response, remission in less than one year and the mean time elapsed for reaching the remission were assessed and compared between the two groups. Chi-square test, Fisher's exact test, t-test and Pearson correlation test were used for data analysis.

Results: The analysis included 65 patients, 42 with DM and 23 with PM. Late Group included 24 patients (seven PM and 17 DM), while Early Group included 41 patients (16 PM and 25 DM). Positive therapeutic response, remission rate within one year was higher in Early Group (80% vs. 46%, P: 0.004). The mean time needed to achieve remission was much less with early treatment (5.5 vs. 11.9 months, P: 0.003). The relapse rate was also lower in Early Group (5% vs. 25%, P < 0.02). The comparison of treatment outcomes showed the same results in both PM and DM, but it was statistically significant in patients with DM.

Conclusions: Early treatment in patients with PM and DM is associated with higher remission rates, shorter treatment period and low complication rates.