Risk of asthma in patients with primary Sjögren’s syndrome: a retrospective cohort study

BACKGROUND Sjögren's syndrome (SS) has been associated with bronchial hyperresponsiveness and asthma; however, no population-based cohort study has been performed. We evaluated the risk of asthma in patients with primary SS in a nationwide population. METHODS We conducted a retrospective cohort study using data from the National Health Insurance Research Database in Taiwan. The primary SS group included 4725 adult patients diagnosed between 2000 and 2006. Each patient was frequency-matched with four people without SS by sex, age and year of diagnosis. The occurrence and hazard ratio (HR) of asthma was monitored by the end of 2011. RESULTS The overall incidence density of asthma was 1.62-fold higher in the primary SS group than in the non-SS group (9.86 vs. 6.10 per 1000 person-years), with a multivariable Cox proportional hazards model measured adjusted HR of 1.38 [95% confidence interval (CI) = 1.21-1.58]. Stratified analyses by sex, age group, and presence of comorbidity revealed that asthma incidences were all higher in the primary SS group than in the non-SS group, and the relative HRs of asthma associated with primary SS were significant in all subgroups. CONCLUSION Patients with primary SS are associated with an increased risk of developing asthma. We should pay more attention to this group of individuals and provide them with appropriate support.