Assessing Mortality Models in Systemic Sclerosis-Related Interstitial Lung Disease

Area of Science:

• Pulmonology
• Rheumatology
• Medical Prognostics

Background:

• Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is a severe complication requiring accurate prognostic assessment.
• Several models exist to predict outcomes in interstitial lung diseases, but their performance in SSc-ILD is not well-established.

Purpose of the Study:

• To compare the prognostic performance of three established models: the gender, age, and lung physiology (GAP) model, the interstitial lung diseases-GAP (ILD-GAP) model, and the smoking history, age, and diffusion capacity of the lung (SADL) model.
• To determine which model best predicts prognosis in a cohort of patients with SSc-ILD.

Main Methods:

• The study analyzed a cohort of 179 SSc-ILD patients diagnosed within one year at a tertiary care center.
• Models were assessed for calibration using standardized mortality ratios (SMR) and for discrimination using concordance (c)-statistics.
• Demographics, clinical characteristics, and mortality data were collected.

Main Results:

• All three models demonstrated comparable discrimination (c-statistics around 0.72).
• The ILD-GAP model significantly underestimated mortality (SMR 1.50).
• The GAP model (SMR 0.90) and SADL model (SMR 1.00) showed acceptable calibration, though SADL underestimated mortality in Stage I ILD.

Conclusions:

• The gender, age, and lung physiology (GAP) model provided the most reliable prognostic information for SSc-ILD patients in this cohort.
• While ILD-GAP underestimated mortality and SADL had subgroup limitations, the GAP model's performance was robust.
• The GAP model is recommended for prognostication in SSc-ILD.