Ankylosing spondylitis patients carry a significantly higher burden for several comorbidities — other diseases — than are found in people without this inflammatory disorder of the same age and sex, a study drawing on real-world medical data reports.
Comorbidities seen to have the highest incidence rates among ankylosing spondylitis patients included hypertension, dyslipidemia (abnormal amount of fat), and depression.
Medical records from two large U.S. administrative claims databases — MarketScan Commercial Claims and Encounters (Commercial) and Medicare Supplemental (Medicare) databases — were analyzed to compare the prevalence and incidence of comorbidities between ankylosing spondylitis patients and matched controls (people without the disease) from the general population.
Controls matched patients’ age, geographic region, index calendar year, and sex.
The records included inpatient services, outpatient services, long-term care, and prescription drug claims. The analysis included records on 6,679 people with ankylosing spondylitis, matched with records from 19,951 controls. All were followed for a median of two years.
Average age was 50.8 for ankylosing spondylitis patients and 51.7 for the others. Around 60 percent of both patients and controls were males – 60.8% and 60.5%, respectively.
Ankylosing spondylitis patients had a higher rate of comorbidities, as shown by higher scores in the Deyo-Charlson Comorbidity Index — a method of categorizing comorbidities according to the International Classification of Diseases (ICD) diagnosis codes.
Among the comorbidities, or other diseases, observed were asthma, cardiovascular diseases, depression, dyslipidemia, gastrointestinal ulcers, malignancies, multiple sclerosis, osteoporosis, sleep apnea, spinal fracture, inflammatory bowel disease (IBD), psoriasis, and uveitis (inflammation of the middle layer of the eye, called the uvea).
Peripheral vascular disease, diabetes, and Parkinson disease affected both ankylosing spondylitis and controls to a similar degree.
But IBD and uveitis were eight and 26 times higher, respectively, in patients with ankylosing spondylitis than in matched controls.
Multiple sclerosis, osteoporosis, and spinal fracture were three- to four-times more likely to affect ankylosing spondylitis patients, which also showed two-times higher incidence rates of asthma, depression, gastrointestinal ulcers, sleep apnea, and venous thromboembolism (a condition where a blood clot forms in a vein).
Among ankylosing spondylitis patients, men and women showed differences in comorbidities: women had an increased risk of developing asthma, depression and osteoporosis, while cardiovascular disease, dyslipidemia, hypertension, malignancies, sleep apnea, and spinal fracture were more common in men.
“On this real-world, US claims-based study, patients with ankylosing spondylitis were shown to have significantly more comorbidities than matched controls,” the researchers wrote.
“This study did not examine the causality of the association between AS and comorbidities. A potential explanation is that patients have shared genetic or environmental risk factors that predispose them to both AS and to the comorbidities,” they noted.
“Other possibilities are that AS may increase the risk of the evaluated comorbidities or that AS may be a marker for or consequence of unidentified risk factors that contribute to the risk of both AS and the comorbidities,” the authors concluded.