To follow up a previous report on the lung function of patients with primary Sjögren's syndrome (SS), and describe the findings having followed up this cohort for a median duration of 10 years (range 8-12 years).
30 patients fulfilling Fox's criteria for definite or probable primary SS were assessed within six months of diagnosis and after a median duration of four and then 10 years by a clinical examination, chest radiograph, and lung function studies (FEV(1), FVC, TLCO, and KCO).
At baseline, symptomatic dyspnoea was a common finding, reported by 13/30 patients, of whom two had evidence of fibrosing alveolitis on plain chest radiograph. Five patients had a carbon monoxide transfer factor (TLCO) more than two standardised residuals below the predicted value. After four years' follow up two further patients developed radiological fibrotic changes and there were significant reductions in TLCO (p<0.02) and transfer coefficient (KCO) (p<0.02) compared with the baseline measurements. At 10 years' follow up four patients had died and four were lost to follow up. One patient with fibrosing alveolitis had died from chest disease. There were no further cases of pulmonary fibrosis identified on plain chest radiograph. The lung function studies showed no further deterioration from the results found at year four with significant improvements in both TLCO (p<0.001) and KCO (p<0.001). Those patients who were anti-Ro antibody positive had significantly lower transfer factors than patients with primary SS without this serological marker (p<0.02).
This long term follow up of lung disease in primary SS is reassuring, and suggests that most patients do not develop progressive lung disease. Pulmonary disease occurs predominantly in anti-Ro antibody positive patients and presents early in the course of the disease.