Opioid use among low back pain patients in primary care: Is opioid prescription associated with disability at 6-month follow-up?

Opioid prescribing for chronic noncancer pain is increasing, but there is limited knowledge about longer-term outcomes of people receiving opioids for conditions such as back pain. This study aimed to explore the relationship between prescribed opioids and disability among patients consulting in primary care with back pain. A total of 715 participants from a prospective cohort study, who gave consent for review of medical and prescribing records and completed baseline and 6 month follow-up questionnaires, were included. Opioid prescription data were obtained from electronic prescribing records, and morphine equivalent doses were calculated. The primary outcome was disability (Roland-Morris Disability Questionnaire [RMDQ]) at 6 months. Multivariable linear regression was used to examine the association between opioid prescription at baseline and RMDQ score at 6 months. Analyses were adjusted for potential confounders using propensity scores reflecting the probability of opioid prescription given baseline characteristics. In the baseline period, 234 participants (32.7%) were prescribed opioids. In the final multivariable analysis, opioid prescription at baseline was significantly associated with higher disability at 6-month follow-up (P<.022), but the magnitude of this effect was small, with a mean RMDQ score of 1.18 (95% confidence interval: 0.17 to 2.19) points higher among those prescribed opioids compared to those who were not. Our findings indicate that even after adjusting for a substantial number of potential confounders, opioids were associated with slightly worse functioning in back pain patients at 6-month follow-up. Further research may help us to understand the mechanisms underlying these findings and inform clinical decisions regarding the usefulness of opioids for back pain. (C) 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.