NEW YORK – Patients with ankylosing spondylitis who used opiate analgesics were five times more likely to report depression than were those who did not, in a retrospective case-control study of 611 patients.
The relationship between opiate usage and depression was significant even though those who took antidepressants or anxiolytics were significantly less likely to use opiates, according to Dr. Jonathan D. Dau of the department of rheumatology at the University of Texas, Houston.
In the study, there were several highly significant distinctions between those who used opiate analgesics and those who did not, but none could be connected to inflammatory activity, Dr. Dau said.
"None of the objective measures of AS [ankylosing spondylitis] disease activity or progression were found to be associated with opiate usage. This adds confirmation to the hypothesis that pain associated with AS may develop from sources other than spinal inflammation alone," he said.
In data presented at the joint meetings of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis and the Spondyloarthritis Research & Treatment Network, a large variety of parameters were compared between the 87 patients who took opiate analgesics intermittently (91%) or continuously (9%) and the remaining 524 who never took opiate analgesics over a follow-up period of up to 4 years. Three centers in addition to the University of Texas contributed AS patients to the analysis. The mean disease duration was 17.6 years.
Although there were no significant differences between users and nonusers of opiates for radiographic severity, as measured with the modified Stoke Ankylosing Spondylitis Spinal Score, or inflammation, as measured with C-reactive protein levels or erythrocyte sedimentation rate, opiate users scored high on subjective measures. Specifically, the odds ratio for a Bath AS Disease Activity Index score of 4 or greater was 5.460 (P less than .0001). The OR for a high patient global pain assessment was 4.240 (P less than .0001).
As for depression, the OR for opiate users relative to nonopiate users was 5.907 (P less than .0001) by self-report and 3.071 (P less than .0001) by the Center for Epidemiologic Study Depression scale. The authors also reported an OR for smoking among opiate users of 2.125 (P = .0018).
Conversely, an analysis of concomitant medication use found that antidepressants correlated with a 63% reduction (OR, 0.371; P = .0004) in the likelihood of opiate use. Anxiolytics correlated with a nearly 90% reduction (OR, 0.124; P less than .0001). There was no significant association with opiate use and use of either NSAIDs or tumor necrosis factor inhibitors.
However, the study found that opiate users were almost three times more likely to be taking prednisone (OR, 2.996; P = .0073) and more than eight times more likely to be taking muscle relaxants (OR, 8.458; P less than .0001). Dr. Dau observed that muscle relaxants on top of opiates "may provide a greater magnitude of pain relief taken together than when taken alone."
Because of the concerns about use of opiates, particularly their propensity to induce dependence, Dr. Dau suggested that it is important to further explore why some patients take these agents in addition to treatments targeted at disease activity. While standard medications such as NSAIDs and TNF inhibitors have been shown to relieve pain, they do not control somatic pain for all patients.
"This is especially true when the pain stems from processes other than inflammation," reported Dr. Dau. More data are needed to determine whether control of depression through antidepressants is a factor for reducing opiate use, he said.
Dr. Dau reported no relevant financial disclosures.