The incidence of clinically diagnosed chronic obstructive pulmonary disease in patients with spondyloarthritis...

To estimate and compare the incidence of chronic obstructive pulmonary disease (COPD) in patients with spondyloarthritis (SpA) to matched population-based references.

Patients with ≥ 1 SpA-diagnosis from an outpatient department of rheumatology/internal medicine (≥ 17 years at diagnosis) between January 1, 2000, and June 30, 2005, were identified in a regional healthcare register. From the same register, five controls without SpA-diagnosis were matched to each SpA-case on age at the first ever SpA-diagnosis for the case, municipality of residence at this time, and sex. SpA-cases and controls were followed from Jan 1, 2006, until first occurrence of either COPD (diagnosed in primary or secondary inpatient/outpatient care), rheumatoid arthritis diagnosis, moving from the region, death, or Dec 31, 2018. The incidence rates of COPD in SpA-cases and controls, overall and by age-groups and sex, and the corresponding incidence rate ratios, were estimated.

A total of 1083/4950 SpA-cases and controls were followed in the present study for 11,790.9/58,876.4 person-years, with 38/220 incident COPD-cases respectively. The estimated incidence of COPD in SpA-cases was 3.22 (95% CI 2.28-4.42) per 1000 person-years, with an incidence rate ratio compared to controls of 0.86 (95% CI 0.59-1.22). Similarly, there were no significant differences in the incidence of COPD in patients with SpA compared to controls in any age group and in both sexes.

In this register-based cohort study the incidence of COPD in patients with SpA was similar to that in matched population-based references, overall and after stratification for sex and age-groups. Key Points • Spondyloarthritis (SpA) has been associated with comorbidities, e.g. cardiovascular disease. However, evidence regarding the relation between SpA and chronic obstructive pulmonary disease (COPD) is limited. • To our knowledge, this is the first study to investigate the incidence of COPD in a population-based cohort of patients with SpA in general and compare it to the background population. • Using a regional register of primary and specialized care, we found no difference in COPD incidence between those diagnosed with SpA and matched population-based references, overall and after stratification for sex and age group. • The results of the present study suggest that there may not be an association between SpA and COPD. However, further studies in other countries and settings are needed.