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

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 ( D LCO ) slopes were obtained from joint models. Latent class mixed models identified clusters of FVC and D LCO 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 D LCO 51±16%. On average, FVC was stable, while there was an annual decline in D LCO 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 D LCO . 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 D LCO (39%) and a higher risk of death or transplantation (HR 52, 95% CI 10–273). 2) Three D LCO trajectories: patients with stable D LCO (n=44, 66%); patients with a slow decline in D LCO (n=12, 18%) of 2.8% per year; patients with a rapid decline in D LCO (n=11, 16%) of 4.8% per year, characterised by a low baseline D LCO (41%) and a higher risk of death or transplantation (HR 156, 95% CI 18–1352).