Evaluation of the comorbidity burden in patients with ankylosing spondylitis using a large US administrative claims data set

Abstract

Comorbidities among US patients with ankylosing spondylitis (AS) are inadequately understood. This study compared the prevalence and incidence of comorbidities between patients with AS and matched controls using national claims databases. Adults enrolled in the MarketScan Commercial and Medicare databases with ≥ 1 inpatient or ≥ 2 non-rule-out outpatient diagnoses of AS between January 1, 2012 and December 31, 2014 were included. Patients had to have ≥ 1 AS diagnosis in 2013; the first AS diagnosis in 2013 was assigned as the index date. Control patients without AS were matched to AS patients on age, geographic region, index calendar year, and sex. Comorbidities were evaluated in AS patients and matched controls during the baseline and follow-up periods (before and after the index date, respectively). Hazard ratios of developing new comorbidities were estimated using Cox proportional hazard models adjusted for patients' characteristics. A total of 6679 patients with AS were matched to 19,951 control patients. In addition to extra-articular manifestations of AS (inflammatory bowel disease [IBD], psoriasis, uveitis), a higher proportion of AS patients had asthma, cardiovascular disease, depression, dyslipidemia, gastrointestinal ulcers, malignancies, multiple sclerosis, osteoporosis, sleep apnea, and spinal fractures during the baseline period than matched controls. After AS diagnosis, a higher proportion of patients developed newly diagnosed cases of cardiovascular diseases, depression, osteoporosis, spinal fracture, IBD, psoriasis, and uveitis than matched controls. In this real-world, US claims-based study, patients with AS were shown to have significantly more comorbidities than matched controls.

Keywords: Ankylosing spondylitis; Claims database; Comorbidities; Matched controls.

Fig. 1

Selection of study cohorts. AS, ankylosing spondylitis. Non–rule-out claims were those not related to a diagnostic or rule-out procedure (e.g., laboratory, pathology, or radiology services). The index date was the date of the first AS diagnosis. Matched controls were assigned the same index date as their matched patient with AS

Fig. 2

Incidence rate ratios of comorbidities in patients with AS vs their matched controls. AS, ankylosing spondylitis; CV, cardiovascular; IBD, inflammatory bowel disease; IRR, incident rate ratio