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Table 1 Characteristics of included studies

From: Retention in opioid agonist treatment: a rapid review and meta-analysis comparing observational studies and randomized controlled trials

Study/Country Design Participants Interventions Outcomes Risk Rating
Ahmadi
2003A
Iran
Randomized controlled trial
Double blind
Duration: 18 weeks
N = 164
Mean age: 31.4 years old Buprenorphine, 33.7 years old Methadone
Male: 100%
Opioid Dependence (DSM-IV criteria)
(1) Buprenorphine 1 mg/day
(2) Buprenorphine 3 mg/day
(3) Buprenorphine 8 mg/day
(4) Methadone 30 mg/day
Retention as measured by completion rates
Ahmadi 2003B
Iran
Randomized controlled trial
Open label
Duration: 24 weeks
N = 204
Mean age: 31.2 years old
Male: 100%
Opioid Dependence (DSM-IV criteria)
(1) Methadone 50 mg/day
(2) Buprenorphine 5 mg/day
Retention as measured by completion rates
Eder, 1998
Austria
Randomized controlled trial
Open-label
Duration: 24 weeks
N = 34
Mean age: 26.35 years old
Sex not specified
Opioid dependence (criteria not specified)
(1) Buprenorphine 7.3 ± 1.8 mg
(2) Methadone 65.6 mg ± 26.6 mg
Retention as measured by dropout rates/completion of study phase
Abstinence from opioids
Toxicology Urine Samples
Gerra, 2004
Italy
Observational, non-randomized study
Duration: 12 weeks
N = 154
Mean age: 32.5 years old
Male: 74.7%
Heroin dependence (criteria not specified)
(1) Methadone 81.5 ± 35.4 mg
(2) Buprenorphine 9.2 ± 3.4 mg
Retention rate as measured using a survival analysis
Abstinence from illicit drugs
Psychiatric comorbidity
Moderate Risk
Johnson, 1992
USA
Randomized controlled trial
Double blind
Duration: 17 weeks
N = 162
Mean age: 33.4 years old Buprenorphine-8,
32.7 years old Methadone-20,
33.1 years old Methadone-60
Males: 69.8%
Opioid addiction
(1) Buprenorphine 8 mg/d
(2) Methadone 20 mg/d
(3) Methadone 60 mg/d
Retention in treatment as measured by percent of patients retained in each treatment
Urine samples negative for opioids
Failure to maintain abstinence
Kamien, 2008
USA
Randomized controlled trial
Double dummy
Duration: 17 weeks
N = 268
Mean age: 37.2 years old Buprenorphine-Naloxone-8,
38.9 years old Buprenorphine-Naloxone-16,
40.3 years old Methadone-45
38.1 years old Methadone-90
Male =
70.7% Buprenorphine-Naloxone-8, 70.7% Buprenorphine-Naloxone-16, 80.8% Methadone-45,
65.8% Methadone-90
Opioid dependence (DSM-IV criteria)
(1) Buprenorphine-naloxone 8–2 mg
(2) Buprenorphine-naloxone 16–4 mg
(3) Methadone 45 mg
(4) Methadone 90 mg
Retention in treatment as measured by weeks in treatment
Opioid abstinence
Medication compliance
Non-opioid drug use
Kosten, 1993
USA
Randomized clinical trial
Double blind
Duration: 24 weeks
N = 140
Mean age:
32 years old Methadone-35,
32 years old Methadone-65,
33 years old Buprenorphine-2,
32 years old Buprenorphine-6,
Male = 73%
Opioid dependence (DSM-III-R criteria)
(1) Methadone 35 mg
(2) Methadone 65 mg
(3) Buprenorphine 2 mg
(4) Buprenorphine 6 mg
Treatment retention as measured by weeks in treatment
Urine toxicology
Self-reported use
Withdrawal symptoms
Addiction Severity Index
Ling,1996
USA
Randomized controlled trial
Double blind
Duration: 52 weeks
N = 225
Mean age:
41.5 years old Buprenorphine-8
40.8 years old Methadone-30
40.1 years old Methadone-80
Male = 79.6%
Opioid dependence (DSM-III-R criteria)
(1) Buprenorphine 8 mg
(2) Methadone 30 mg
(3) Methadone 80 mg
Retention as measured by weeks in treatment, and as measured by percent of patients retained in each treatment
Opioid use
Opioid craving
Adverse events
Maremmani, 2007
Italy
Observational study
Duration: 52 weeks
N = 213
Mean age: 31 years old
Opioid dependence (DSM-IV criteria)
Male = 82.6%
(1) Buprenorphine 5.1 mg
(2) Methadone 61.68 mg
Retention in treatment as mesured by percent of patients retained in each treatment
Longitudinal analysis
Adverse events
Low Risk
Otiashvili, 2013
Georgia
Randomized Controlled Trial
Duration = 12 weeks
N = 80
Mean age: 33.7 years old
Opioid dependence (ICD-10 criteria)
(1) Methadone 39 ± 17.8 mg
(2) Buprenorphine (Suboxone) 8.5 ± 3.5 mg
Retention in treatment as measured by weeks in treatment, and number of patients retained in each treatment
Urine toxicology
HIV risk injection behaviours
Adverse events
Pani, 2000
Italy
Randomized Controlled Trial
Double blind
Duration = 24 weeks
N = 72
Mean age: 28 years old
Male: 86.1%
Heroin addiction of at least 2 years (DSM-IV criteria for opioid dependence)
(1) Buprenorphine 8 mg
(2) Methadone 60 mg
Retention in treatment as measured by proportion of patients retained in each treatment
Urine toxicology
Predictors of treatment compliance
Adverse events
Proctor, 2014
USA
Retrospective chart review
Duration: 24 weeks
N = 3233
Mean age:
Male: 55.9% Methadone,
57.8% Buprenorphine (Suboxone), 50.05% Buprenorphine (Subutex)
(1) Methadone 64.64 mg/d
(2) Buprenorphine (Suboxone) 9.75 mg/d
(3) Buprenorphine (Subutex) 12.21 mg/d
Retention in treatment as measured by length of stay in days, and percent of patients retained in each treatment
UDS Findings
Moderate Risk
Schottenfeld, 1997
USA
Randomized controlled trial Double blind
Duration: 24 weeks
N = 116
Mean age:
32.6 years old Methadone-65,
32.6 years old Buprenorphine-12,
31.6 Methadone-20,
33.7 Buprenorphine-4
Male:
57% Methadone-65,
69% Buprenorphine-12,
72% Methadone-20,
77% Buprenorphine-4
(1) Methadone 20 mg
(2) Methadone 65 mg
(3) Buprenorphine 4 mg
(4) Buprenorphine 12 mg
Treatment retention as measured by completion rates
Urine toxicology
  1. Risk rating legend: A: random sequence generation (selection bias); B: allocation concealment (selection bias); C: blinding of participants and personnel (performance bias); D: blinding of outcome assessment (detection bias); E: incomplete outcome data (attrition bias); amber circle: unclear