Pain medication associated with decreased physical performance and rehabilitation progress

The effects of pain medication on physical performance in chronic pain are poorly understood. We examined the association between analgesics and physical performance in people with chronic musculoskeletal pain (CMSP) requiring rehabilitation.

We classified participants into 3 categories according to the highest level of medication used at admission for rehabilitation: no analgesics (NAs), nonopioid analgesics (NOAs), and opioid analgesics (OPAs). We measured performance with functional tests (6-minute walk test [6MWT], progressive isoinertial lifting evaluation [PILE], steep ramp test, handgrip strength test [HST], 5 times sit-to-stand test, and 1-minute stair-climbing test [1MSCT]) at admission and discharge. Multiple regression models were used to assess the differences in functional capacity between the 3 groups, adjusting for potential confounders.

We included 4,339 individuals; 1,731 took no analgesics (40%), 1,742 took NOAs (40%), and 866 took OPAs (20%). The median consumption was 11.7 mg per day according to morphine-equivalent dose calculation. Physical performance was poorer for patients taking than those not taking analgesics in all tests examined. We found a negative gradient in performance with increasing WHO analgesic ladder. The odds of achieving clinically significant improvements in 4 tests (6MWT, PILE, HST affected side, and 1MSCT) was reduced for people taking opioids compared with the NA group.

Given the inconclusive and limited evidence for the benefit of analgesics on pain and disability in CMSP, health professionals should be aware of these results for even low doses of opioids, which were associated with poor physical performance and rehabilitation progress.