Eight-year follow-up of airway hyperresponsiveness in patients with primary Sjögren's syndrome.

Objective: To evaluate in a longitudinal study the influence of airway hyperresponsiveness (AHR) on lung function in patients with primary Sjögren's syndrome (pSS).

Methods: Lung function was studied over an eight-year period in 15 patients who fulfilled the Copenhagen criteria for primary Sjögren's syndrome and who were covered in our earlier published study on AHR in patients with Sjögren's syndrome. Standard spirometry and measurements of lung volumes, diffusing capacity (DLCO), and AHR to methacholine were performed.

Results: A significant decline over time was found in total lung capacity (TLC), vital capacity (VC), forced vital capacity (FVC), functional residual capacity (FRC), and expiratory midflows (FEF). A sign of small airway obstruction (decrease in FEF) at entry correlated with VC at follow-up (r = .8, P < .003), and the individual change in FEF during the observation period correlated with the individual change in VC (r = .6, P < .05). Six patients had increased AHR, and three of them had decreased DLCO. Six of the patients progressively reduced DLCO over time, and five of them had spirometric signs of increased small airway obstruction.

Conclusions: During this eight-year follow-up we observed that one-third of the patients with pSS developed a significant reduction in lung function. Our findings suggest that small airways obstruction and AHR are associated with reduction of VC and development of impaired DLCO as a sign of interstitial lung disease in this group of patients.