A multicenter study found that interstitial lung disease developing in late systemic sclerosis showed comparable progression rates and severity to earlier-onset disease, suggesting ongoing surveillance value in patients with longstanding systemic sclerosis.
In the study, published in Arthritis & Rheumatology, investigators analyzed the data from 969 patients with systemic sclerosis (SSc) without prevalent interstitial lung disease (ILD) at baseline who were enrolled in the Canadian Scleroderma Research Group cohort from 2004 to 2020. Among these patients, 199 (21%) of them developed incident ILD over a median follow-up of 2.4 years (interquartile range [IQR] = 1.2–4.3).
The study defined late SSc as disease duration ≥ 7 years from first non-Raynaud manifestation. While the incidence rate of ILD was lower in late SSc (3.7 per 100 person-years) compared with earlier SSc (5.4 per 100 person-years), disease severity metrics were similar between both groups. Force Vital Capacity values were comparable (88.3% vs 87.2%), as were DLCO values (63.5% vs 61.8%).
Imaging findings showed similar patterns between late- and early-onset groups. Ground glass opacities were present in 50% of late-onset and 53% of early-onset cases. Fibrotic interstitial changes were seen in 78% of late-onset and 71% of early-onset cases, while honeycombing appeared in 18% and 19% respectively.
Risk factors for developing late-onset ILD included male sex (odds ratio [OR] = 0.56, 95% confidence interval [CI] = 0.33–0.97), non-White ethnicity (OR = 0.53, 95% CI = 0.33–0.85), diffuse cutaneous involvement (OR = 1.77, 95% CI = 1.22–2.57), anti-topoisomerase I antibodies (OR = 3.77, 95% CI = 2.32–6.11), and anti-RNA polymerase III antibodies (OR = 1.84, 95% CI = 1.14–2.98).
Disease progression occurred in 45% (n = 48/106) of patients with incident ILD over a median follow-up of 3.1 years (IQR = 2.1–4.0). The investigators found no statistically significant difference in progression rates between late- and earlier-onset groups (adjusted hazard ratio = 1.11, 95% CI = 0.58–2.10).
Treatment data showed that only 8.7% (n = 29) of person-visits involved immunosuppressive therapy, with mycophenolate mofetil (21 cases) being most common, followed by cyclophosphamide (11), tocilizumab (3), and rituximab (1). Treated patients demonstrated lower mean FVC (84.9% vs 93.6%, P = .004) and numerically lower DLCO values (63.6% vs 71.3%, P = .06).
The study had several limitations, including non-systematic HRCT screening, exclusion of nearly 50% of the study population from progression analyses because of missing pulmonary function test results, and limited data on medication dosing and duration. The small number of treated patients also restricted analysis of treatment effectiveness.
The research was supported by multiple funding sources, including the Université de Montréal Scleroderma Chair, Sclérodermie Québec, and the Canadian Institutes of Health Research.
Conflict of interest disclosures were not made available.
