Psychological therapies for the management of chronic pain (excluding headache) in adults

BACKGROUND: Chronic non-cancer pain, a disabling and distressing condition, is common in adults. It is a global public health problem and economic burden on health and social care systems and on people with chronic pain. Psychological treatments aim to reduce pain, disability and distress. This review updates and extends its previous version, published in 2012. OBJECTIVES: To determine the clinical efficacy and safety of psychological interventions for chronic pain in adults (age > 18 years) compared with active controls, or waiting list/treatment as usual (TAU). SEARCH METHODS: We identified randomised controlled trials (RCTs) of psychological therapies by searching CENTRAL, MEDLINE, Embase and PsycINFO to 16 April 2020. We also examined reference lists and trial registries, and searched for studies citing retrieved trials. SELECTION CRITERIA: RCTs of psychological treatments compared with active control or TAU of face-to-face therapies for adults with chronic pain. We excluded studies of headache or malignant disease, and those with fewer than 20 participants in any arm at treatment end. DATA COLLECTION AND ANALYSIS: Two or more authors rated risk of bias, extracted data, and judged quality of evidence (GRADE). We compared cognitive behavioural therapy (CBT), behavioural therapy (BT), and acceptance and commitment therapy (ACT) with active control or TAU at treatment end, and at six month to 12 month follow-up. We did not analyse the few trials of other psychological treatments. We assessed treatment effectiveness for pain intensity, disability, and distress. We extracted data on adverse events (AEs) associated with treatment. MAIN RESULTS: We added 41 studies (6255 participants) to 34 of the previous review's 42 studies, and now have 75 studies in total (9401 participants at treatment end). Most participants had fibromyalgia, chronic low back pain, rheumatoid arthritis, or mixed chronic pain. Most risk of bias domains were at high or unclear risk of bias, with selective reporting and treatment expectations mostly at unclear risk of bias. AEs were inadequately recorded and/or reported across studies. CBT The largest evidence base was for CBT (59 studies). CBT versus active control showed very small benefit at treatment end for pain (standardised mean difference (SMD) -0.09, 95% confidence interval (CI) -0.17 to -0.01; 3235 participants; 23 studies; moderate-quality evidence), disability (SMD -0.12, 95% CI -0.20 to -0.04; 2543 participants; 19 studies; moderate-quality evidence), and distress (SMD -0.09, 95% CI -0.18 to -0.00; 3297 participants; 24 studies; moderate-quality evidence). We found small benefits for CBT over TAU at treatment end for pain (SMD -0.22, 95% CI -0.33 to -0.10; 2572 participants; 29 studies; moderate-quality evidence), disability (SMD -0.32, 95% CI -0.45 to -0.19; 2524 participants; 28 studies; low-quality evidence), and distress (SMD -0.34, 95% CI -0.44 to -0.24; 2559 participants; 27 studies; moderate-quality evidence). Effects were largely maintained at follow-up for CBT versus TAU, but not for CBT versus active control. Evidence quality for CBT outcomes ranged from moderate to low. We rated evidence for AEs as very low quality for both comparisons. BT We analysed eight studies (647 participants). We found no evidence of difference between BT and active control at treatment end (pain SMD -0.67, 95% CI -2.54 to 1.20, very low-quality evidence; disability SMD -0.65, 95% CI -1.85 to 0.54, very low-quality evidence; or distress SMD -0.73, 95% CI -1.47 to 0.01, very low-quality evidence). At follow-up, effects were similar. We found no evidence of difference between BT and TAU (pain SMD -0.08, 95% CI -0.33 to 0.17, low-quality evidence; disability SMD -0.02, 95% CI -0.24 to 0.19, moderate-quality evidence; distress SMD 0.22, 95% CI -0.10 to 0.54, low-quality evidence) at treatment end. At follow-up, we found one to three studies with no evidence of difference between BT and TAU. We rated evidence for all BT versus active control outcomes as very low quality; for BT versus TAU. Evidence quality ranged from moderate to very low. We rated evidence for AEs as very low quality for BT versus active control. No studies of BT versus TAU reported AEs. ACT We analysed five studies (443 participants). There was no evidence of difference between ACT and active control for pain (SMD -0.54, 95% CI -1.20 to 0.11, very low-quality evidence), disability (SMD -1.51, 95% CI -3.05 to 0.03, very low-quality evidence) or distress (SMD -0.61, 95% CI -1.30 to 0.07, very low-quality evidence) at treatment end. At follow-up, there was no evidence of effect for pain or distress (both very low-quality evidence), but two studies showed a large benefit for reducing disability (SMD -2.56, 95% CI -4.22 to -0.89, very low-quality evidence). Two studies compared ACT to TAU at treatment end. Results should be interpreted with caution. We found large benefits of ACT for pain (SMD -0.83, 95% CI -1.57 to -0.09, very low-quality evidence), but none for disability (SMD -1.39, 95% CI -3.20 to 0.41, very low-quality evidence), or distress (SMD -1.16, 95% CI -2.51 to 0.20, very low-quality evidence). Lack of data precluded analysis at follow-up. We rated evidence quality for AEs to be very low. We encourage caution when interpreting very low-quality evidence because the estimates are uncertain and could be easily overturned. AUTHORS' CONCLUSIONS: We found sufficient evidence across a large evidence base (59 studies, over 5000 participants) that CBT has small or very small beneficial effects for reducing pain, disability, and distress in chronic pain, but we found insufficient evidence to assess AEs. Quality of evidence for CBT was mostly moderate, except for disability, which we rated as low quality. Further trials may provide more precise estimates of treatment effects, but to inform improvements, research should explore sources of variation in treatment effects. Evidence from trials of BT and ACT was of moderate to very low quality, so we are very uncertain about benefits or lack of benefits of these treatments for adults with chronic pain; other treatments were not analysed. These conclusions are similar to our 2012 review, apart from the separate analysis of ACT.