The prevalence of chronic obstructive pulmonary disease in patients with spondyloarthritis compared to the general population in the southernmost region of Sweden: a case-control study.

Spondyloarthritis (SpA) has been associated with comorbidities, e.g., cardiovascular disease. However, little is known about the relation between SpA and chronic obstructive pulmonary disease (COPD). The aim of the study was to compare the prevalence of COPD in SpA to the general population. Patients with prevalent SpA in Skåne, Sweden, on December 31, 2018, were identified based on diagnostic codes in a regional register on primary care, secondary outpatient care and inpatient care. Population-based controls (5 per SpA case) were matched for age, sex and municipality. The base case definition for COPD required at least two prior visits with a registered COPD diagnosis. Stricter definitions included dispensed prescriptions for COPD and a COPD diagnosis made by a specialist in lung medicine. The prevalence of COPD in patients with SpA and controls, overall and stratified by sex and age, and the corresponding prevalence ratios, were estimated. A total of 3571 patients with SpA (51% male, mean age 53 years) were compared to 17,855 matched controls. The prevalence of COPD in patients with SpA was 37.8/1000, with a prevalence ratio compared to controls of 1.03 (95% CI 0.85-1.24). There were no significant differences in COPD prevalence between patients with SpA and controls in men or women, in any of the age groups, or in analyses using stricter definitions of COPD. In this regional study including data from primary care, the prevalence of COPD was not increased in patients with SpA compared to the background population.