The world's largest review of opioid pain relievers prescribed for acute pain found these medicines provide only small, short-term relief for some acute conditions and are ineffective for some others.
Led by researchers from the University of Sydney, the study set out to review the efficacy and harms of opioid pain relievers (eg codeine, morphine, oxycodone, tramadol) compared with placebo for acute pain. The review includes 59 systematic reviews covering more than 50 acute pain conditions in children and adults, and comprehensively maps where opioids are effective and where evidence is lacking. The review provides the strongest and most comprehensive evidence to date on when opioids do and do not work for acute pain.
The findings were published today in Drugs, one of the most prestigious journals on medicines.
"Opioids are among the most commonly prescribed treatments for acute pain, however, our review found that they did not provide large or lasting pain relief compared with placebo for the vast majority of acute pain conditions, with pain relief typically lasting only a few hours," said lead author Associate Professor Christina Abdel Shaheed, from the School of Public Health at the University of Sydney.
"Overall, oral opioids were only slightly better than placebo for acute musculoskeletal pain, which they are often prescribed for, in the six to 48 hours after starting treatment. Opioids also increased the risk of side effects when used for acute musculoskeletal pain, some types of post-surgical pain or traumatic limb pain.
"By showing that the benefits are generally small, short-lived, absent for many common conditions, and sometimes harmful, our research challenges the widely held belief that opioids are the most effective 'go-to' option for acute pain".
Key findings of the systematic overview and meta-analysis:
Opioids provide only small, time-limited pain relief for some pain conditions like stomach pain, dental surgery, ear procedures, traumatic limb pain, pain following childbirth, caesarean pain and bunionectomy (bunion removal).
Opioids were no better than placebo for some limb surgeries, kidney stone pain, pain after removal of tonsils and pain in newborns on assisted breathing devices.
Opioids were not consistently beneficial over time for heart-related pain, pain following hysterectomy (removal of a woman's uterus) and topical use (patches) for dermatological (skin) pain.
Opioids increased the risk of side effects compared with placebo when used for acute musculoskeletal pain, traumatic limb pain and pain after some types of surgery. Side effects included nausea and vomiting.
Very short-term use of opioids can reduce pain for some acute conditions, however, regular use comes with a risk of harm including dependence and tolerance. Serious opioid-related harms can include misuse, overdose, hospitalisation and deaths.
Inadequate reporting of side effects means the true risks of these medicines are likely underestimated, urging better reporting of harms in clinical trials, and highlighting the need for safer, and more effective alternatives.
Overall, the evidence does not support regular opioid use for acute pain and some studies evaluated single doses, which does not reflect real world use.
Concerns over opioid use and misuse
"Persistent use of opioid medicines can develop quickly following first time use (sometimes within days), and may arise from regular use for acute pain," said co-first author Dr Stephanie Mathieson from the University of Sydney's Institute for Musculoskeletal Health and School of Pharmacy.
"It is important that patients are informed about the potential harms from opioids when prescribed them, and that doctors prescribe these medicines judiciously (lowest effective dose for the smallest amount of time) for acute pain," she said.
Co-first author Associate Professor Joshua Zadro from the University's Institute for Musculoskeletal Health and School of Health Sciences added: "These findings are important for patients across all age groups who experience acute pain, doctors treating these conditions and policy makers who regulate the safe use of these medicines in the community."
