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CMAJ Open. 2015 Jul 17;3(3):E344-51. doi: 10.9778/cmajo.20140089. eCollection 2015 Jul-Sep.

Sex differences in outcomes of methadone maintenance treatment for opioid use disorder: a systematic review and meta-analysis.

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MiNDS Neuroscience Graduate Program (Bawor), McMaster University, Hamilton, Ont.; Population Genomics Program (Bawor, Dennis, Desai, Pare, Samaan), Chanchlani Research Centre, McMaster University, Hamilton, Ont.; Department of Clinical Epidemiology and Biostatistics (Dennis, Pare, Thabane), McMaster University, Hamilton, Ont.; Bachelor of Health Sciences Undergraduate Program (Bhalerao), McMaster University, Hamilton, Ont.; Ontario Addiction Treatment Centre (Plater, Worster, Varenbut, Daiter), Richmond Hill, Ont.; Department of Medicine (Worster, Marsh, Anglin), McMaster University, Hamilton, Ont.; Northern Ontario School of Medicine (Marsh), Sudbury, Ont.; Department of Psychiatry and Behavioural Neurosciences (Steiner, Anglin, Samaan), McMaster University, Hamilton, Ont.; Women's Health Concerns Clinic (Steiner), St. Joseph's Healthcare Hamilton, Hamilton, Ont.; Department of Obstetrics and Gynecology (Steiner), McMaster University, Hamilton, Ont.; Biostatistics Unit (Thabane), Centre for Evaluation of Medicine, Hamilton, Ont.; Peter Boris Centre for Addiction Research (Samaan), St. Joseph's Healthcare Hamilton, Hamilton, Ont.



Opioid use disorder is a serious international concern with limited treatment success. Men and women differ in their susceptibility to opioid use disorder and response to methadone treatment and can therefore benefit from sex-specific treatment. We performed a systematic review of the literature on outcomes of methadone maintenance treatment for opioid use disorder in men and women related to drug use, health status and social functioning.


We searched PubMed, Embase, PsycINFO and CINAHL for observational or randomized controlled studies involving adults 18 years of age or older undergoing methadone treatment for opioid use disorder. Studies were included if they investigated sex differences in methadone treatment outcomes. Two authors independently reviewed and extracted data. Meta-analyses were performed when possible; risk of bias and quality of evidence were also assessed.


Twenty studies with 9732 participants were included, of which 18 were observational and 2 were randomized controlled trials. Men and women differed significantly in alcohol use (odds ratio [OR] 0.52, 95% confidence interval [CI] 0.31 to 0.86), amphetamine use (OR 1.47, 95% CI 1.12 to 1.94), legal involvement (OR 0.63, 95% CI 0.47 to 0.84) and employment during treatment (OR 0.39, 95% CI 0.21 to 0.73). Opioid use patterns were similar among men and women. Risk of bias was moderate, and quality of evidence was generally low.


Sex differences were evident in polysubstance use, legal involvement and employment status among men and women receiving methadone treatment for opioid use disorders. Although the quality of evidence was low, our review highlights the need for improved implementation of sex-specific treatment strategies.

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