KL-6 is a long-term disease-activity biomarker for interstitial lung disease associated with polymyositis/dermatomyositis, but is not a short-term disease-activity biomarker

Abstract

Objectives: We aimed to evaluate the usefulness of serum KL-6 for interstitial lung disease (ILD) with polymyositis/dermatomyositis (PM/DM).

Methods: All consecutive and previously untreated adult patients with PM/DM who were admitted to our hospital from 2010 to 2015 were included. The associations between serum KL-6 levels and clinical information were retrospectively analyzed.

Results: Baseline serum KL-6 levels were significantly higher in patients with ILD than in those without (n = 41 and 15, respectively; p < .001). In the 14 patients whose ILD improved within 4 weeks post-treatment, their serum KL-6 levels did not significantly decrease at 2 weeks, 4 weeks, or 3 months post-treatment (p = 1.00, 1.00, and .83, respectively). Conversely, their serum KL-6 levels significantly decreased at 6, 9, and 12 months post-treatment (p = .01 in all comparisons). In the 12 patients whose ILD remained unchanged or deteriorated in 4 weeks post-treatment, only the difference between their serum KL-6 levels at 3 and 12 months was significant (p = .003).

Conclusions: The present study validated the serum KL-6 as a diagnostic marker for ILD in PM/DM. However, serum KL-6 is not a short-term disease-activity biomarker for ILD with PM/DM, but it is a long-term disease-activity biomarker.

Keywords:

• Dermatomyositis
• interstitial lung disease
• KL-6
• polymyositis

Acknowledgements

We thank Cambridge English Correction Service for the English language editing. We thank Dr. Masataka Kuwana (Department of Allergy and Rheumatology, Nippon Medical School Graduate School of Medicine, Tokyo, Japan) for the assessment of serum myositis-specific autoantibodies.

Conflict of interest

None.

Additional information

Funding

This work was supported by the Japanese MEXT (The Ministry of Education, Culture, Sports, Science and Technology) KAKENHI (Grants-in-Aid for Scientific Research) [grant numbers 26461242, 17K09715].