Oral Opioids No Better Than NSAIDs for Knee OA Pain
Written by Editor   
Friday, April 01, 2016 12:00 AM

Oral opioids do not provide better pain relief than oral non steroidal anti-inflammatory drugs (NSAIDs) for knee osteoarthritis (OA), according to a systematic review.  “Patients who failed NSAIDs and are considering opioids should be aware that the pain relief from opioids is likely to be no greater than the pain relief they had with NSAIDs, but may provide 'an extra chance' before considering total knee replacement." 

The researchers identified 17 studies that met inclusion criteria, which included randomized controlled trials published in English between 1982 and 2015 that evaluated oral NSAIDs or opioids for knee OA; were of at least 8 weeks' duration; were conducted in Western Europe, the Americas, New Zealand, or Australia; and used the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain subscale to assess baseline and follow-up pain.

Baseline demographics and efficacy withdrawal rates were similar for the NSAID and opioid studies. Baseline pain and toxicity withdrawal rates were slightly lower in NSAID studies.

Corrected for efficacy-related withdrawals, all drug classes were associated with pain reductions of 18 to 19 points on the WOMAC Pain scale. Regression analysis revealed no difference in effectiveness by drug class. Specifically, there were no significant differences in knee OA pain reduction for NSAIDs vs less potent opioids, for NSAIDs vs potent opioids, or for less potent opioids vs more potent opioids.

The researchers were also surprised to find that the placebo effect might be influenced by the type of comparator drug being tested, such that the placebo effect appeared to be greater in trials testing opioids than in those testing NSAIDs. "This is a very interesting observation that complements and expands on growing evidence that 'placebo' or 'intention' effects of different treatments differ by the intensity of the treatment delivery," Dr Losina explained. "For example, placebo effect of surgery is greater than placebo effect of injection, which in turn is greater than placebo effect of a pill. What we saw is some evidence that even within the same 'delivery' class — pills — the placebo or intention effect depends on anticipated potency of the analgesic regimen."

“In general, the use of opioid analgesics for the treatment of OA should be discouraged."

Source:   http://www.medscape.com/viewarticle/858845