Interstitial lung disease can develop ‘in any stage’ of systemic sclerosis
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SAN DIEGO — Shortness of breath, male sex, age and elevated inflammatory markers are all more predictive of new interstitial lung disease in systemic sclerosis than disease duration, according to data presented at ACR Convergence 2023.
“ILD is associated with morbidity and mortality in patients with systemic sclerosis,” Liubov Petelytska, MD, PhD, of University Hospital Zurich, in Switzerland, said at a press conference during the meeting. “The prevalence of ILD is well established and the most prognostic factor associated with ILD is systemic sclerosis, reflecting the prevalent cases, not the incident cases. That’s why the aim of our study was to evaluate the incidence rate of new developing ILD in patients who test negative on screening tests conducted at baseline.”
To analyze the annual incidence of ILD, as well as the risk factors for new onset of ILD, in patients with SSc, Petelytska and colleagues identified and assessed 5,331 patients with SSc but without ILD at baseline, based on high-resolution computed tomography (HRCT) results. Those with pulmonary arterial hypertension, based on right heart catheterization, were excluded. After follow-up imaging, the researchers split their cohort into patients who developed new-onset ILD and those who remained negative for ILD.
The researchers calculated the rate of SSc-associated ILD (SSc-ILD) per 1,000 person-years, starting from the patient’s first visit. They then used prediction models to identify risk factors for ILD, with logistic regression for 1-year and Cox regression for long-term assessments. The researchers chose known predictors of new-onset ILD as covariates, based on previous literature and expert opinion.
Among a total of 5,336 patients with SSc included at baseline, 1,080 — or 20.2% — ultimately developed new-one ILD within a median of 3.8 years of follow-up. According to the researchers, the overall incidence rate of ILD was 74 per 1,000 person-years (95% CI, 68.5-79.5). In addition, Petelytska and colleagues reported observing new-onset ILD continuously during the longitudinal follow-up period, for up to 10 years after baseline. Incidence rates ranged from 54.5 to 82.9 per 1,000 person-years during this time.
Long-term predictors of new-onset ILD included stage 2 or higher dyspnea via the NYHA criteria (HR = 1.23; 95% CI, 1.08-1.4), male sex (HR = 1.28; 95% CI, 1.1-1.5), age (HR = 1.02; 95% CI, 1.01-1.02), single-breath diffusing capacity of the lung (HR = 0.99; 95% CI, 0.98-0.99), elevated inflammatory markers (HR = 1.59; 95% CI, 1.35-1.87), hemoglobin level (HR = 0.94; 95% CI, 0.9-0.98), anti-topoisomerase I antibodies (HR = 2.15; 95% CI, 1.82-2.53), anti-centromere antibodies (HR = 0.47; 95% CI, 0.39-0.56,) and digital ulcers (HR = 1.77; 95% CI, 1.49-2.08).
Meanwhile, disease duration was not a significant predictor of new-onset ILD.
To examine 1-year incidence, the researchers included 13,339 yearly follow-ups from 4,067 patients who were negative for ILD at baseline. This analysis confirmed all of the above long-term ILD risk factors, except for digital ulcers.
“ILD can develop in any stage of SSc, and not only in SSc patients in the early years from disease onset,” Petelytska said. “We need to check on these patients who have these negative prognostic factors for the possibility of developing ILD. That’s why we need to perform on an annual basis the HRCT screening.”
Perspective
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David A. McLain, MD, MACR, FACP, FRCP
The understanding of interstitial lung disease in scleroderma has changed over the years. When I was in training, ILD was considered a late manifestation of SSc. A rheumatology textbook from 1994 discussed ILD as occurring in the “later stages of systemic sclerosis.” The present study shows that ILD appears at all stages of the disease and that screening for ILD should continue even with a normal high-resolution computed tomography lung scan. This is an important change in thinking from what was taught in the past.
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Petelytska L. Abstract 1700. Presented at: ACR Convergence 2023; Nov. 10-15, 2023; San Diego.
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