Tsur 2008.

Methods	Individual randomised controlled trial. Estimated that use of contraception would be 50% in the control group, and a sample size of 100 would be required to detect 30% improvement in contraceptive use, with 80% power at a 0·05 level of significance
Participants	108 females of reproductive age (16 to 45 years of age), some users and some not users of contraception, using or planning to use isotretinoin (a drug for acne), who phoned the Drug Consultation Centre at Assaf Harofeh Medical Center in Israel seeking advice regarding isotretinoin
Interventions	Control group: Routine care comprised information on Isotretinoin including contraceptive use only during the initial interview. Intervention group: automated intervention aimed to increase contraception use and comprised routine care plus additional information about teratogenic risk and the importance of contraceptive use in mailed written form and by text messages sent to cellular phones 1 month and 2 months after the initial call
Outcomes	Primary outcome: contraceptive use in women taking isotretinoin (methods of contraception not stated). Secondary outcomes: use of 2 contraceptives, sexual activity, contraceptive use amongst sexually active participants. All outcomes assessed by phone call at 3 months
Behaviour change techniques	As defined by study authors: not described According to Abraham and Michie's typology: 2 behaviour change techniques used (see Table 2)
Notes	5 participants (5%) lost to follow‐up at 3 months and not included in the final analysis. Differential loss to follow‐up between intervention and control groups not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random numbers kept in sealed envelopes
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not described in adequate detail. Sealed envelopes used, but unclear whether they were sequentially numbered and opaque
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding possible; outcome may have been influenced by lack of blinding
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information on whether outcome assessors were aware of allocation
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing outcome data balanced in numbers across intervention groups
Selective reporting (reporting bias)	Unclear risk	Study protocol not available. The primary outcome is reported using measurements that were not prespecified in the Methods section of the paper
Other bias	High risk	Possibility of detection (social desirability) bias with self report measures of contraception use

OC: oral contraceptive

STI: sexually transmitted infection