Fracture Incidence and Risk Factors Among Patients With Ankylosing Spondylitis

Among patients with ankylosing spondylitis (AS), older age, history of fracture, and use of opioids were associated with increased risk for fracture, according to study results published in Arthritis Care and Research (Hoboken).

Investigators assessed the incidence rate (IR) of and factors related to fracture among adults with AS.

A retrospective cohort study was performed with data taken from the Rheumatology Informatics System for Effectiveness (RISE) registry: a national electronic health record rheumatology registry that is linked to Medicare claims. Study participants included adult patients with 2 AS diagnosis codes and associated Medicare claims occurring at least 30 days apart in the RISE database.

After gathering baseline data, patients were followed-up to assess for the incidence and rate of fractures and any associated factors. The primary outcome was incidence of any fracture, while further outcomes included incidence of fracture according to location.

A total of 1426 patients were included in the analysis. The mean age of the study group was 69.4 years, 44.3% were women, and 77.3% were non-Hispanic White.

Overall, 260 fractures occurred among 197 patients, which translated into an IR of 76.7 per 1000 person years (PY) (95% CI, 66.38-88.62 per 1000 PY).

Men and women were equally likely to have a fracture (odds ratio [OR], 0.90; 95% CI, 0.64-1.26). However, older age (OR, 2.80; 95% CI, 1.39-5.65), previous fracture (OR, 5.24; 95% CI, 3.44-7.99), and use of the equivalent of more than 30 mg of morphine (OR, 1.86; 95% CI, 1.08-3.19) were associated with increased risk for fracture.

Vertebral fractures were the most common, with an IR of 21.1 per 1000 PY (95% CI, 16.2-27.5 per 1000 PY). Vertebral fractures most often occurred in the thoracic spine (18 patients; IR, 6.9 per 1000 PY), followed by cervical (14 patients; IR, 5.4 per 1000 PY) and lumbar (<10 patients; IR, 2.7 per 1000 PY) fractures.

Study limitations included potential bias among conclusions, the short follow-up period, and missing data on certain patient demographics and disease activity. Additionally, the generalizability of results does not apply to patients aged less than 65 years, as they were not dually eligible for Medicare and Medicaid.

The study authors concluded, “Given that opioid use was associated with fracture in AS, this high-risk population should be considered for interventions to mitigate risk.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.