Population-based Estimates of Common Comorbidities and Cardiovascular Disease in Ankylosing Spondylitis

Objective: To study the rate of common comorbidities and cardiovascular disease in patients with ankylosing spondylitis (AS) compared with the general population seeking health care.

Methods: This cohort study included 935 subjects (67% men) ages ≥20 years diagnosed with AS and the adult background population in Southern Sweden. During 2004 to 2007 we recorded the occurrence of physicians' diagnostic codes for a select number of comorbidities commonly associated with AS and cardiovascular disease and risk factors. We obtained standardized morbidity-rate ratios (SMRs) by dividing the observed morbidity rate in AS patients by the expected rate based on the corresponding rate of the disease in the general population of the county seeking health care.

Results: The highest SMRs were found for uveitis (34.35, 95% confidence interval [95% CI] 28.55-40.98) and inflammatory bowel disease (9.28, 95% CI 7.07-11.97). Also, we found increased SMRs for ischemic heart diseases (2.20, 95% CI 1.77-2.70), hypertension (1.98, 95% CI 1.72-2.28), and diabetes mellitus (1.41, 95% CI 1.10-1.78). Furthermore, the SMRs for psoriasis, osteoporosis, and atrioventricular blocks were also statistically significantly elevated.

Conclusion: Inflammatory diseases affecting the eye and the digestive system were the most notable comorbidities in AS patients, but the rate for cardiovascular disease was also high. Using comprehensive longitudinal population-based register data is a promising tool to evaluate the excess consultation rate and total burden of rheumatic disease on patients and society.