Authors' objectives: Chronic pain is common and costly. Antidepressants are prescribed to reduce pain. However, there has not been a network meta-analysis examining all antidepressants across all chronic pain conditions, so effectiveness and safety for most antidepressants for pain conditions remain unknown. To assess the efficacy and safety of antidepressants for chronic pain (except headache) in adults. Our primary outcomes were as follows: substantial pain relief (50%), pain intensity, mood and adverse events. Our secondary outcomes were as follows: moderate pain relief (30%), physical function, sleep, quality of life, Patient Global Impression of Change, serious adverse events and withdrawal. Chronic pain is common in adults, and often has a detrimental impact upon physical ability, well-being, and quality of life. Previous reviews have shown that certain antidepressants may be effective in reducing pain with some benefit in improving patients’ global impression of change for certain chronic pain conditions. However, there has not been a network meta-analysis examining all antidepressants across all chronic pain conditions. Our objective was to assess the efficacy and safety of antidepressants for chronic pain (except headache) in adults. Our primary outcomes were as follows: substantial pain relief (50%), pain intensity, mood and adverse events. Our secondary outcomes were as follows: moderate pain relief (30%), physical function, sleep, quality of life, Patient Global Impression of Change (PGIC), serious adverse events and withdrawal.

Authors' results and conclusions: We identified 176 studies with a total of 28,664 participants. Most studies were placebo-controlled (n = 83) and parallel armed (n = 141). The most common pain conditions examined were fibromyalgia (59 studies), neuropathic pain (49 studies) and musculoskeletal pain (40 studies). The average length of randomised controlled trials was 10 weeks. Most studies measured short-term outcomes only and excluded people with low mood and other mental health conditions. Across efficacy outcomes, duloxetine was consistently the highest-ranked antidepressant with moderate- to high-certainty evidence. Standard dose was equally efficacious as high dose for the majority of outcomes. Milnacipran was often ranked as the next most efficacious antidepressant, although the certainty of evidence was lower than that for duloxetine. There was insufficient evidence to draw robust conclusions for the efficacy and safety of any other antidepressant for chronic pain. There is only reliable evidence for duloxetine in the treatment of chronic pain. Duloxetine was moderately efficacious across all outcomes at standard dose. There is also promising evidence for milnacipran, although further high-quality research is needed to be confident in these conclusions. Data for all other antidepressants were of low certainty. However, the findings should not be read as an encouragement to prescribe antidepressants where other non-pharmacological intervention could be equally effective, especially in the absence of good evidence on side effects and safety.

Authors' methods: This was a systematic review with a network meta-analysis. We searched CENTRAL, MEDLINE, EMBASE, CINAHL, LILACS, AMED and PsycINFO databases for randomised controlled trials of antidepressants for chronic pain conditions up until 4 January 2022. The review was registered in PROSPERO (CRD42020171855), and the protocol was published in the Cochrane Library (https://doi.org/10.1002/14651858.CD014682). We analysed trials from all settings. We included trials in which participants had chronic pain, defined as longer than 3 months, from any condition excluding headache. We included all antidepressants. Our primary outcome was substantial pain relief, defined as a reduction ˃ 50%. We also measured pain intensity, mood and adverse events. Secondary measures included moderate pain relief (above 30% reduction), physical function, sleep, quality of life, Global Impression of Change, serious adverse events, and withdrawal from trial. The evidence for antidepressants other than duloxetine is poor. For duloxetine, it is not clear whether the effect applies to groups with both pain and low mood, since these groups were excluded from trials. There is also insufficient evidence on long-term outcomes and on adverse effects. We included adults (aged 18 years or older) reporting primary or secondary pain in any part of their body (except headache) as their primary complaint, that matched the International Association for the Study of Pain definition of chronic pain (i.e. at least 3 months’ duration). We included all trials regardless of the severity of participants’ chronic pain, although we extracted whether severity was part of the inclusion criteria of the individual studies. We excluded studies where the participants’ primary pain condition was headache or migraine.

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR128782

Year Published: 2024

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/MKRT2948

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/MKRT2948

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk