Validation of the MCK model for predicting outcomes in myopathy-associated interstitial lung disease: a multicentre...

To validate the MCK model's prognostic utility in patients with idiopathic inflammatory myopathy (IIM)-associated interstitial lung disease (ILD).

This retrospective study included 242 patients with IIM-associated ILD from the multicentre MYKO cohort. Patients were classified as anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive or antibody-negative. The MCK score was defined by the number of criteria met: C-reactive protein (CRP) ≥ 0.8 mg/dL and Krebs von den Lungen 6 (KL-6) ≥ 1000 U/ml for MDA5-positive patients; CRP ≥ 1.1 mg/dL and KL-6 ≥ 1000 U/ml for MDA5-negative patients. Outcomes included all-cause mortality, disease flares, and infections requiring hospitalisation, which were assessed via Kaplan-Meier and Cox regression analyses.

Amongst MDA5-positive patients, an MCK score of 2 did not significantly predict mortality. However, in MDA5-negative patients, an MCK score of 2 was significantly associated with an increased risk of all-cause mortality, disease flares, and infections requiring hospitalisation. Subgroup analyses from 2018 onward showed similar patterns, although statistical significance was not maintained.

The MCK model demonstrates strong predictive performance for all-cause mortality and disease complications, particularly in patients with MDA5-negative IIM. However, its predictive utility may have declined in recent years, possibly due to advancements in treatment approaches.