Jones 2001.

Methods	RCT. No difference between groups on baseline drug use or demographic characteristics.
Participants	80 pregnant women on MMT, greater than 18 years of age, meeting DSM‐II‐R criteria for opiate dependence with cocaine abuse, admitted for first time for substance abuse treatment. Mean age 28; mean gestational age 23.4; 96% unemployed; 85% single/never married; 76% African American; 20% chronic medical conditions (HTN, DM, HIV); DSM‐III‐R: 100% opiate dependent, 69% cocaine, 5% marijuana, 10% alcohol.
Interventions	For all participants treatment consisted of a 7‐day residential followed by 7 days of intensive outpatient (7 days/week, 6.5 hours/day). Treatment consisted of group counselling and at least once a week individual psychotherapy. All received MMT, mean dose 42. Money vouchers could be earned for specific target behaviour: attend at least 4 hours counselling and (days 8‐14) provide a cocaine negative urine sample (n = 44). No voucher incentives (n = 36). Duration 14 days.
Outcomes	Attendance was measured as mean full day attendance as well as "perfect treatment attendance" defined as attendance on at least 13 or 14 full days of treatment. Retention was measured as the % drop out. Urine samples were collected daily from days 8 to 14 and reported as % positive.
Notes	Transportation, child care, on site PNC and psychiatric consultation provided. We contacted the trial authors who were unable to provide raw data.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomization procedure involved patients selecting one of two different color chips from a hat with replacement following each selection…" Specific process outlined that provides participants with equal chance of assignment.
Allocation concealment (selection bias)	Unclear risk	Allocation concealment was not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition data specified and descriptions of different analytic methods to account for missing data outlined.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No references to outcome assessor blinding made.