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Introduction Pulmonary arterial hypertension (PAH) is a leading cause of mortality in systemic sclerosis (SSc). PAH is typically considered as a late complication, but some evidence suggests it may occur earlier. We aimed to assess the incidence, risk factors, clinical characteristics, and outcomes of SSc-associated PAH according to disease duration at diagnosis.Material and Methods We conducted a retrospective cohort study using data from the Canadian Scleroderma Research Group registry (2004–2020). Included patients fulfilled the 2013 ACR/EULAR SSc classification criteria and had no prevalent PAH at baseline. Incident PAH was defined by right heart catheterization (mean pulmonary artery pressure >=25 mmHg, pulmonary capillary wedge pressure <15 mmHg) or, if unavailable, then by echocardiographic criteria combined with PAH-specific treatment. Disease duration was stratified as early (<7 years) or late (>=7 years) from first non-Raynaud symptom. Risk factors were assessed using marginal logistic regression with generalized estimating equations. Survival was analyzed with Kaplan-Meier curves and time-dependent Cox models.Results Among 1,367 SSc patients with available right heart catheterization or echocardiography data, 1,294 were eligible for analysis after excluding those with prevalent PAH or alternative causes of pulmonary hypertension at baseline. During follow-up, 53 patients (4.1%) developed incident PAH over 6,621 person-years (0.8 cases per 100 person-years). Of these, 15 (28%) occurred within 7 years of SSc onset. In early SSc, older age, telangiectasias, and diffuse cutaneous involvement were associated with PAH, while anti-centromere antibodies, calcinosis, and digital ulcers were not. In comparison, in late SSc, PAH was associated with older age, White ethnicity, anti-centromere antibodies, and limited cutaneous subtype. Early-onset PAH patients showed numerically lower DLCO, higher FVC/DLCO ratios, and more severe NYHA class compared to late-onset PAH. Over a median follow-up of 4.9 years, survival was numerically, but not significantly worse in early- versus late-onset PAH (5-year survival 31.7% vs 68.4%, HR = 1.62, 95% CI: 0.54–4.82).Conclusions PAH may develop early in SSc and displays distinct clinical and immunological profiles compared to late-onset disease. Early-onset PAH patients tend to have more severe functional impairment and possibly worse survival. These findings highlight the need for systematic PAH screening from the early stages of SSc, particularly in diffuse cutaneous disease.Abstract P.131 Figure 1