Concordance and Prognostic Relevance of Different Definitions of Systemic Sclerosis Interstitial Lung Disease...

Rationale: Interstitial lung disease (ILD) in systemic sclerosis (SSc) is a common complication that has a varied progression rate and prognosis. Different progression definitions are available, including minimal clinically important worsening of FVC, EUSTAR (European Scleroderma Trials and Research Group) progression, OMERACT (Outcome Measures in Rheumatology Clinical Trials) progression, and Erice ILD working group progression. Pulmonary function and symptom changes may act as specific confounding factors when applying these definitions in SSc. Objectives: To assess the concordance and prognostic value of four different definitions in patients with SSc-ILD overall and in specific clinical groups. Methods: Progression status in consecutive patients with SSc-ILD was assessed over 24 months, and 60-month disease-related mortality risk was compared between progressors and nonprogressors using four definitions. Measurements and Main Results: Among 245 patients, 26 SSc-related deaths were reported. Mortality was linked to progression for minimal clinically important worsening of FVC (hazard ratio [HR], 2.27; 95% confidence interval [CI], 1.03-4.97), OMERACT (HR, 2.90; 95% CI, 1.28-6.57), and Erice definitions (HR, 2.69; 95% CI, 1.23-5.89). The association between progression and mortality was poor in patients with disease duration ≥3 years, mild functional impairment, and pulmonary artery systolic pressure ≥40 mm Hg. Erice criteria appeared superior in patients with duration ≥3 years, limited cutaneous variant, and pulmonary artery systolic pressure <40 mm Hg. OMERACT criteria performed better in diffuse cutaneous variant patients with severe functional impairment. Conclusions: The four evaluated definitions of progression in SSc-ILD are not interchangeable, resulting in up to one-third of cases being classified differently on the basis of adopted criteria and presenting different prognostic values, particularly within specific clinical groups.