Predictive factors for sustained remission with stratification by myositis-specific autoantibodies in adult polymyositis/dermatomyositis

Abstract

Objective: The aim of this study was to clarify predictive factors for sustained remission in adult patients with PM/DM, particularly focusing on stratification by myositis-specific autoantibodies (MSAs).

Methods: A total of 162 adult patients with PM/DM who were followed up for >1 year after diagnosis were retrospectively enrolled. MSAs were evaluated comprehensively in 102 patients whose sera were available. Sustained remission was defined as no evidence of disease activity (active skin rash, active myositis or active interstitial lung disease) for longer than a 6-month continuous period while undergoing myositis therapy or no medication. Clinical data were reviewed in patients' medical charts.

Results: The sustained remission rate for all patients was 58% during the median follow-up period at 4 years. With regard to MSAs, the achievement rate of sustained remission among MSA-negative patients was significantly higher than that for patients with anti-aminoacyl-tRNA synthetase (P = 0.004), anti-melanoma differentiation-associated gene 5 (P = 0.037) or anti-transcriptional intermediary factor 1-γ (P = 0.013) antibodies. MSA-negative status (odds ratio 5.84, P = 0.009) and absence of severe muscle weakness requiring assistance at diagnosis (odds ratio 43.6, P < 0.001) were independent factors associated with sustained remission in multivariate analysis. Cumulative remission rates were significantly higher (P < 0.001) in patients with both the MSA-negative status and absence of severe muscle weakness at diagnosis than the others.

Conclusion: MSA-negative status and the absence of severe muscle weakness requiring assistance at diagnosis are independent predictive factors for sustained remission in adult PM/DM patients.

Keywords: dermatomyositis; myositis-specific autoantibodies; polymyositis; prediction; remission; treatment outcome.