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Introduction Interstitial lung disease (ILD) is a leading cause of mortality in systemic sclerosis (SSc). Half present with mild disease, of whom 25% progress over two years. Our aim was to explore demographic, clinical, and serological predictors of progression in mild SSc-ILD.Material and Methods We conducted an international retrospective cohort study using data from the Canadian Scleroderma Research Group (CSRG), Australian Scleroderma Cohort Study (ASCS), Centre hospitalier de l’Université de Montréal (CHUM), and Stanford University SSc cohorts. Patients were included if they had ILD, forced vital capacity (FVC) >= 80% predicted, and available follow-up pulmonary function test data. ILD was diagnosed on HRCT or, if unavailable, then by chest X-ray or on physical exam with the presence of typical Velcro-like crackles, based on a published algorithm. ILD progression was defined as a relative decrease of at least 10% in FVC, or a relative decrease of 5 to 10% in FVC with a relative decline of at least 15% in DLCO. Multivariable Cox regression analyses were used to analyze the association between each predictor variable and time to ILD progression, adjusting for age, sex, ethnicity, smoking, and disease duration from first non-Raynaud symptoms.Results A total of 591 patients were analyzed, including 280 CSRG, 232 ASCS, 56 CHUM and 23 Stanford patients. Mean age was 58.8 ± 11.8 years, 84% were female, 87% were White, 44% had diffuse SSc, and median disease duration was 7.4 [2.9, 15.9] years at time of mild ILD diagnosis. Of these, 304 patients progressed over a mean follow-up of 3.6 years. Factors associated with a shorter time to ILD progression included age (HR: 1.01, 95% CI: 1.00, 1.02), non-White ethnicity (HR: 1.41, 95% CI: 1.02, 1.95), diffuse subtype (HR: 1.29, 95% CI: 1.01, 1.64), higher modified Rodnan skin score (mRSS, HR: 1.07, 95% CI: 1.00, 1.13 for every 5-unit increase), and lower % predicted DLCO (HR: 0.96, 95% CI: 0.93, 1.00 for every 5-unit increase). SSc-specific antibodies were not associated with progression.Conclusions In this international cohort, we identified risk factors associated with a shorter time to ILD progression in mild forms of SSc-ILD. These features warrant closer monitoring and earlier treatment in this population and can inform enrichment strategies for interventional trials.Abstract P.108 Table 1Demographic, clinical and serological characteristics associated with risk of mild SSc-ILD progression, in unadjusted and adjusted models