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Table 1 Summary of characteristics of included studies and Risk of Bias (RoB)

From: Interim opioid agonist treatment for opioid addiction: a systematic review

Study ID (Design, Country)

Participants

Intervention

Study’s primary outcomes

Risk of Bias (RoB)

Yancovitz et al. 1991

(Randomized Controlled Trial (RCT), USA) [44]

301 participants:

149 Treatment group

152 Frequent contact group

Interim Clinic: Methadone administered by a nurse 5 days a week. Saturday medication and one take-home were provided at another site in the same building + AIDS education + free condoms. Minimal counseling on an ad hoc basis. Biweekly urine samples. Maintenance dose of 80 mg/d approximately

Control: Waiting list, biweekly follow-up and urine samples, and free condoms. Time spent limited to one month and then switched into experimental group

Change in heroin use

Random sequence generation: Unclear

Allocation concealment: Low

Blinding of participants and personnel: High

Blinding of outcome assessment (objective outcomes): Unclear

Blinding of outcome assessment (subjective outcomes): Unclear

Incomplete data outcome: High

Selective reporting bias: Unclear

Schwartz et al. 2006

(RCT, USA) [21]

319 participants:

199 Treatment group

120 Waiting list

Interim Treatment: Methadone provided under direct observation, participants attended 7 days a week (as the federal regulation required). 3 consecutive unexcused missed doses resulted in discharge from treatment. Mean dose of methadone was 78.4 mg/d

Control: Waiting list; no further contact with clinical staff unless their name came up on the waiting list

Entry into comprehensive methadone treatment

Self-reported days of heroin use

Self-reported days of cocaine use

Self-reported criminal behavior

Number of urine drug test results positive for heroin and cocaine

Retention in treatment

Random sequence generation: Low

Allocation concealment: Low

Blinding of participants and personnel: High

Blinding of outcome assessment (objective outcomes): Low

Blinding of outcome assessment (subjective outcomes): High

Incomplete data outcome: High

Selective reporting bias: Unclear

NCT02360007

(RCT, USA) [41]

50 participants:

25 Treatment group

25 Waiting list

Interim Treatment: Interim buprenorphine treatment (IBT) participants will complete buprenorphine (BUP) induction in Week 1 (or longer if required), during which they will attend the clinic daily. Thereafter, during Weeks 2–12 IBT participants will visit the clinic every two weeks to take their BUP dose, provide a urine specimen and receive their remaining doses in a secure dispenser that makes each day’s dose available during a 3-h window

Control: Waitlist control (WLC) participants will remain on the waitlist for their treatment of choice. They will visit the clinic to complete follow-up assessments and provide staff-observed urines according to the same schedule as IBT participants

Participants in both conditions will complete follow-up assessments and provide a urine specimen at 4, 8, 12, 18 and 24 weeks after trial entry. WLC participants who have not entered treatment by Week 12 will be offered IBT at that time, providing an additional within-subject evaluation of IBT effects. Thus the overall possible study duration may vary between 12—28 weeks

Negative results for illicit opioids

Random sequence generation: Low

Allocation concealment: Unclear

Blinding of participants and personnel: High

Blinding of outcome assessment (objective outcomes): Unclear

Blinding of outcome assessment (subjective outcomes): Unclear

Incomplete data outcome: High

Selective reporting bias: High

NCT00712036

(RCT, USA) [37]

230 participants:

99 Treatment group (IM)

104 Control condition 1 (SM)

27 Control condition 2 (RM)

Interim Treatment (IM): Methadone treatment for up to 4 months with emergency counseling only. Treatment was provided following federal regulations. Mean methadone dose of 91.8 mg/d (SD 21.3)

Control:

1. Scheduled counseling/Standard Methadone Treatment (SM): Methadone treatment with counseling as usual. Methadone treatment programs (MTPs) usual practices, which permitted take-home doses contingent upon tenure and progress in treatment (e.g., negative drug tests), required regularly scheduled counseling, treatment planning, other psychosocial treatment as needed, and more frequent drug testing than in IM. Mean methadone dose of 79.4 mg/d (SD 22.3)

2. Restored Methadone Treatment (RM): Methadone treatment with counseling provided by a clinician with a lower caseload than counseling as usual. That counselor carried a reduced case load not to exceed 25 patients and was instructed to see the participants as frequently as the participants wanted and the counselor deemed appropriate. Mean methadone dose of 64.7 mg/d (SD 15.6)

Opiate positive drug test

Random sequence generation: Low

Allocation concealment: Low

Blinding of participants and personnel: High

Blinding of outcome assessment (objective outcomes): Low

Blinding of outcome assessment (subjective outcomes): High

Incomplete data outcome: Low

Selective reporting bias: Low

Krook et al. 2002

(RCT, Norway) [35]

106 participants:

55 Treatment group

51 Control condition

Buprenorphine: Buprenorphine without additional rehabilitation or support. 4 mg Subutex® on the first day, increased to 16 mg/d on the following 8 days. At the 12th week, dosage was scaled down to 4 mg/d

Control: Placebo without additional rehabilitation or support. 4 mg of Subutex® on the first day and then the dose was decreased to 0 in 9 days and thereafter replaced by placebo

Retention (is the patient still in the project?)

Compliance (how many of the total number of doses had been taken?)

Random sequence generation: Low

Allocation concealment: Low

Blinding of participants and personnel: Low

Blinding of outcome assessment (objective outcomes): Low

Blinding of outcome assessment (subjective outcomes): Low

Incomplete data outcome: Unclear

Selective reporting bias: Low

Friedmann et al. 1994

(Cohort study, USA) [33]

977 participants:

314 Treatment group

663 Control condition

Interim Methadone Treatment: A physical examination on admission was performed by a physician, methadone was administered by a registered nurse six days per week with one take-home dose for Sunday, and education about AIDS-risk reduction was provided. Only crisis counseling services were provided, and the focus of the interim clinic counselors was otherwise limited to AIDS-risk reduction. The clinic had a capacity of 150 patients, thus providing a ratio of 1 counselor to 75 patients

Control: The comparison group includes all consecutive 1990 and 1991 admissions to Beth Israel's traditional methadone clinics located in the same immediate area as the interim clinic

Retention rate in treatment

Confounding: Serious

Selection of participants: Serious

Classification of intervention: Low

Deviation from intended intervention: Serious

Missing outcome data: Low

Measurement of the outcome: Low

Selection of the reported result: Low