Berenson 2012.

Methods	Design: individually randomized Location: southeast Texas (USA) Time frame: enrollment from July 2006 to January 2010 Sample size calculation (and outcome of focus): N = 190 in each group (570 total) for 90% power to detect OR of 2.0 for oral contraceptive (OC) continuation after 12 months
Participants	General with N: 1155 women; 16 to 24 years of age Source: 5 public reproductive health clinics in southeast Texas serving low income women Inclusion criteria: sexually active; non‐pregnant; 16 to 24 years old; requesting OC initiation Exclusion criteria: desire to become pregnant in next year; medical contraindication to OC; current or prior (> 1 month) OC use
Interventions	Study focus: increasing contraceptive adherence as well as dual‐method use to prevent STI and pregnancy. Theory or model: health belief model Treatment C: standard care (below) plus 45 minutes of contraceptive counseling from study staff C + P: C (above) + phone calls by contraceptive counselor (weekly until initiation then monthly for 6 months) and access to 24‐hour toll‐free number (N = 384) Comparison or control: standard care from nurse practitioner with written protocol for new OC users Duration: 6‐month intervention
Outcomes	Primary: OC adherence (consistent OC use); dual‐method use (consistent OC use and consistent condom use); condom use at last sex (if inconsistent condom user); pregnancy Secondary: NA Follow‐up: by telephone at 3, 6 12 months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization scheme (PLAN procedure, SAS Institute)
Allocation concealment (selection bias)	High risk	When asked about concealment before assignment, investigator communicated that they did not conceal from researchers but did conceal from participants
Blinding of participants and personnel (performance bias) All outcomes	High risk	Presume no blinding of participants; not feasible due to type of intervention
Blinding of outcome assessment (detection bias)	Low risk	Staff who made assessment phone calls were blinded to intervention group
Outcome measures	Unclear risk	Pregnancy by self‐report and medical record review (low risk); contraceptive use by self‐report (high risk)
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow‐up by 12 months: 44% counseling, 43% counseling + phone, and 45% standard care.
Other bias	Unclear risk	Analysis for cluster randomized trial: NA