Long-term functional course of Sjögren's disease-associated interstitial lung disease

Abstract

Background Interstitial lung disease (ILD) is common in primary Sjögren's disease (pSD); its functional course is poorly known. Our aim was to characterise the long-term functional course and prognosis in patients with pSD-ILD. We determined the role of baseline demographic and clinical variables in the evolution of lung function and identified risk factors for death or transplantation. Methods In a retrospective observational cohort study, patients with pSD and ILD were retrospectively identified from two French ILD centres. Forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO) slopes were obtained from joint models. Latent class mixed models identified clusters of FVC and DLCO trajectories. Results We included 73 patients (63% women, mean age 63 years), with a median follow-up of 9.3 years. At baseline, mean FVC was 73±21% and DLCO 51±16%. On average, FVC was stable, while there was an annual decline in DLCO of 1% of the predicted value. Male sex, a pattern of usual interstitial pneumonia (UIP) or indeterminate for UIP on high-resolution computed tomography (HRCT), and features of fibrosis on HRCT, were associated with an accelerated decline in FVC and DLCO. Conclusion We identified clusters of lung function evolution. 1) Two FVC trajectories: patients with stable FVC (n=56, 78%); patients with FVC decline (n=16, 22%) of 2.4% per year, characterised by a low baseline DLCO (39%) and a higher risk of death or transplantation (HR 52, 95% CI 10–273). 2) Three DLCO trajectories: patients with stable DLCO (n=44, 66%); patients with a slow decline in DLCO (n=12, 18%) of 2.8% per year; patients with a rapid decline in DLCO (n=11, 16%) of 4.8% per year, characterised by a low baseline DLCO (41%) and a higher risk of death or transplantation (HR 156, 95% CI 18–1352).