Identifying Patients with Systemic Sclerosis and Progressive Pulmonary Fibrosis in a Real-World Setting: Data from UK Tertiary Rheumatology and ILD Centres

Objectives: Systemic sclerosis-related interstitial lung disease (SSc-ILD) has high associated morbidity and mortality. With early diagnosis and treatment, we can improve clinical outcomes with immunosuppression. Some patients develop progressive pulmonary fibrosis (PPF) and are eligible for anti-fibrotic therapy. There are limited data on the incidence and prevalence of PPF in the SSc ILD cohort to guide case finding. We investigated this using data from UK tertiary Rheumatology and ILD centres. Methods: Patients with systemic sclerosis across two UK rheumatology units were identified using electronic records searched from 2021 to 2023 and were compared against established PPF diagnostic criteria. Results: 255 patients were identified. Prevalence of PPF was 5.49% and in those with established SSc-ILD, 23%. Median time to development of PPF was 5 years. In 64% of patients with PPF diagnosis, they had had systemic sclerosis for over 10 years. Incidence of PPF in patients with SSc was 3.9% and in those with known SSc-ILD 16.%. Only 50% of patients who met criteria for PPF had been referred to respiratory for consideration of antifibrotic initiation. Patients with a predominantly fibrotic baseline radiological pattern (UIP) had a trend towards development of PPF (p = 0.07). No patient with a predominantly inflammatory baseline pattern developed PPF (p = 0.021). Conclusions: Real world data have shown a prevalence of PPF in the SSc-ILD cohort of 23% with a median time of 5 years to development from diagnosis of SSc. Our data show active case finding may be incomplete and rheumatologists must be cognisant of PPF when evaluating patients with SSc.