Opioid usage among patients with ankylosing spondylitis (AS) was more likely to be associated with subjective measures (depression, high disease activity/functional impairment) than objective measures (C-reactive protein [CRP] levels and erythrocyte sedimentation rate [ESR]), suggesting that pain in AS may derive from sources other than spinal inflammation alone. This according to a recent prospective cohort study of 706 patients with AS followed at least 2 years, who underwent comprehensive clinical evaluation of disease activity and functional impairment. These were assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI). Medications taken concurrently with opioids, as well as CRP levels and ESR, were determined at each study visit, performed every 6 months. Researchers found:

• Factors significantly associated with opioid usage, especially chronic opioid use, included longer disease duration, smoking, lack of exercise, higher disease activity and functional impairment, depression, radiographic severity, and cardiovascular disease.
• Patients taking opioids were more likely to be using anxiolytic, hypnotic, antidepressant, and muscle relaxant medications.