ILD affects systemic sclerosis outcomes

The presence of interstitial lung disease at systemic sclerosis diagnosis appears to affect disease outcomes, with data indicating that even mild lung fibrosis is associated with reduced survival, according to a Norwegian study published in the American Journal of Respiratory and Critical Care Medicine.

The researchers evaluated ILD among all 815 patients with systemic sclerosis living in Norway between 2000 and 2012, including all incident cases occurring during the study period as well as prevalence cases diagnosed before 2000. Eighty percent of patients had high-resolution CT scans available and 86% underwent pulmonary function testing at baseline. Standardized mortality ratios were then assessed in 2018 for the 630 incident cases and 15 individually matched controls.

At baseline, lung fibrosis was apparent in 50% of the patients who underwent high-resolution CT, the mean FVC predicted was 94% — with 42% having FVC greater than 100% — and the mean diffusing capacity of the lung for carbon monoxide was 69%.

Among the patients who underwent pulmonary function testing at baseline, 48% had follow-up testing performed after a mean of 6.2 years. Of these patients, 33% had declines in pulmonary function indicative of severe ILD progression and 13% had declines indicative of moderate ILD progression.

Among the 82% of 630 incident patients with baseline lung high-resolution CT imaging, mortality was linked to the extent of lung fibrosis, with the standardized mortality ratio increasing from 2.2 for patients with no fibrosis to 8 for patients with fibrosis greater than 25%.

Furthermore, results demonstrated an inverse association between standardized mortality ratio and baseline FVC, with the ratio increasing at all FVC levels less than 100%. Additionally, 5- and 10-year survival rates for patients with normal-range baseline FVC were 83% and 80%, respectively, for patients with no fibrosis and 69% and 56%, respectively, for patients with lung fibrosis (P = .03).

“Our results indicate a dose-response relationship between lung fibrosis extent and standardized mortality ratio, and between FVC and standardized mortality ratio, evident even in groups with mild lung fibrosis and within normal-range FVC,” the researchers wrote. “Taken together, the results from this study suggest that all patients with systemic sclerosis should be screened with pulmonary function tests and high-resolution CT at baseline to diagnose ILD early and tailor further management.”

In an accompanying editorial, Michael P. Keane, MD, FRCPI, from University College Dublin and St. Vincent’s University Hospital in Dublin, noted that the study builds on existing knowledge about the effects of ILD in systemic sclerosis but does not yet provide information on other important aspects of treatment for this patient population.

“From the Norwegian experience, there is now good evidence to recommend baseline CT in all patients with systemic sclerosis. Patients who show any evidence of fibrosis on imaging should have close follow-up and serial pulmonary function tests, as even mild disease at baseline can have severe disease progression,” he wrote. “Remaining questions are, how do we predict which subgroup of patients will have a significant decline, how should we follow patients with no fibrosis at baseline, and who and when do we treat?” – by Melissa Foster

Disclosures: Hoffmann-Vold reports she has received personal fees from Actelion, Boehringer Ingelheim and GlaxoSmithKline. Please see the study for all other authors’ relevant financial disclosures. Keane reports he has received personal fees and nonfinancial support from Boehringer Ingelheim and Roche.