Scope of opioid analgesics for treating low back pain
It is a very common practice to use opioid analgesics for the treatment of low back pain. However, there has been no clinical evidence till now that explains the systematic evaluation of the effect of opioid dose and use of enrichment study design on estimates of treatment effect.
Recently, a group of investigators conducted a study in which they have tried to evaluate effectiveness & tolerability of opioids in managing back pain and also the consequence effect of opioid dose and use of an enrichment study design on treatment effect.
Sources used to extract data were Medline, EMBASE, CENTRAL, CINAHL, and PsycINFO with citation tracing from suitable randomized clinical trials (RCTs). Placebo-controlled RCTs in any language were selected. Data was taken out from the sources independently by two authors and risk of biasness was assessed. Random effects model was used to pool the data with strength of evidence evaluated using the grading of recommendations assessment, development, and evaluation (GRADE). Pain was the primary outcome. Pain and disability outcomes were changed to a common 0 to 100 scale, with effects greater than 20 points considered clinically significant.
From the total 20 RCTs of opioid analgesics (7925 participants), 13 trials (3419 participants) assessed short-term effects on chronic low back pain. No placebo-controlled trials enrolled patients with acute low back pain. Fifty percent patients in half of the trials experienced adverse events or lack of efficacy, leading to their withdrawal. There was moderate-quality evidence about the short term pain reduction: mean difference (MD), −10.1 (95% CI, −12.8 to −7.4). With every 1 log unit increase in morphine equivalent dose, meta-regression revealed a 12.0-point greater pain relief. No significant pain relief was seen within the dose range evaluated (40.0-240.0-mg morphine equivalents per day). Also, there was no important effect of enrichment study design.
The short term relief with opioid analgesics in patients with chronic low back pain is uncertain and is also not clinically significant with guideline recommended doses. There is lack of evidence on long-term effectiveness of opioids. In acute low back pain too, the efficiency of opioid analgesics is not known.