High‐dose opioids for chronic non‐cancer pain: an overview of Cochrane Reviews

Background This overview was originally published in 2017, and is being updated in 2022. Chronic pain is typically described as pain on most days for at least three months. Chronic non‐cancer pain (CNCP) is any chronic pain that is not due to a malignancy. Chronic non‐cancer pain in adults is a common and complex clinical issue, for which opioids are prescribed by some physicians for pain management. There are concerns that the use of high doses of opioids for CNCP lacks evidence of effectiveness, and may increase the risk of adverse events. Objectives To describe the evidence from Cochrane Reviews and overviews regarding the efficacy and safety of high‐dose opioids (defined as 200 mg morphine equivalent or more per day) for CNCP. Methods We identified Cochrane Reviews and overviews by searching the Cochrane Database of Systematic Reviews in The Cochrane Library. The date of the last search was 21 July 2022. Two overview authors independently assessed the search results. We planned to analyse data on any opioid agent used at a high dose for two weeks or more for the treatment of CNCP in adults. Main results We did not identify any reviews or overviews that met the inclusion criteria. The excluded reviews largely reflected low doses or titrated doses, where all doses were analysed as a single group; we were unable to extract any data for high‐dose use only. Authors' conclusions There is a critical lack of high‐quality evidence, in the form of Cochrane Reviews, about how well high‐dose opioids work for the management of CNCP in adults, and regarding the presence and severity of adverse events. No evidence‐based argument can be made on the use of high‐dose opioids, i.e. 200 mg morphine equivalent or more daily, in clinical practice. Considering that high‐dose opioids have been, and are still being used in clinical practice to treat CNCP, knowing about the efficacy and safety of these higher doses is imperative.