Study discovers risk factors for new-onset interstitial lung disease in systemic sclerosis

Interstitial lung disease (ILD) is a major consequence and cause of death in people with systemic sclerosis (SSc). Although the frequency and risk factors for ILD are well understood, little is known about the annual incidence and risk factors associated with the condition in people who test negative on baseline screening tests.

Liubov Petelytska, MD, PhD, a postdoctoral researcher at the University Hospital in Zurich, and her colleagues used data from the European Scleroderma Trials and Research (EUSTAR) group, an international scleroderma research network, to answer these concerns.

Results showed that new-onset ILD occurred in 1,075 or 20.2 per cent of patients with a median of 3.8 years follow-up. Overall incidence was 3.83 per 100 person-years and could occur anytime during a 10-year observation period from baseline.

"We included both smoking and ethnicity in our prediction models and, surprisingly, they were not statistically significant," Petelytska says.

"That might be an influence of the EUSTAR database, enrolling over 99 per cent of Caucasian patients and underrepresenting African Americans. The reproducibility of our results in other races and ethnicities is limited, and it should be replicated and validated."

The biggest surprise, Petelyska says, was that disease duration was not a significant predictor of new ILD.

"It is commonly believed that ILD [mainly] appears in the early years of systemic sclerosis onset. Instead, we found that the onset of ILD was independent of disease duration, which was not included in the prediction model. To confirm this surprising result, we performed a sensitivity analysis, dividing patients with early and late disease onset, and this still showed similar incidence rates. These results indicate that screening should be repeated during follow-up, possibly on a yearly basis, together with screening for pulmonary hypertension and routine clinical observation."

Petelytska says the study has several limitations, especially the heterogeneity of patients included in the analysis.

"We had patients having two to 10 follow-up visits, as well as patients observed from one to 10 years after baseline," she said.

"In addition, not all patients with ILD-negative status on baseline had follow-up HRCT information available, which might bias the results of our incidence rate of SSc-ILD."

Registry data with missing values and decentralized reading and lack of knowledge about medication can also lead to possible bias, Petelytska said.

The next stage of the project is to study different medications to determine whether they can effectively prevent ILD.

"It is our plan to include both immunosuppressants and vasoactive and vasodilating drugs, which are among those most commonly administered to SSc patients," Petelytska said. (ANI)