Kataoka 2010.

Methods	Study design: randomised controlled trial Randomisation method: random numbers table Power calculation: none reported Study dates: from February to November 2003
Participants	Setting: antenatal clinic of an urban general hospital Country: Japan Inclusion criteria: women < 25 weeks pregnant Exclusion criteria: none stated Number (%) of eligible recruited: 328/355 (92.4%) Numbers randomised 328: interview 165, questionnaire 163 Numbers analysed (% recruited) at first time point 328: interview 165 (100%), questionnaire 163 (100%) Number of dropouts at second time point: interview 10, questionnaire 3 Numbers analysed (% recruited) at second time point: 315; interview 155 (93.9%), questionnaire 160 (98.2%) Number of dropouts at third time point: interview 7, questionnaire 11 Numbers analysed (% recruited) at third time point: 297; interview 148 (89.7%), questionnaire 149 (91.4%) Age: 20 to 29 years 30.5%, 30 to 39 years 66.2%, ≥ 40 years 3% Marital status: married 96.3%, single 2.1% Education: high school 13.4%, junior college 43.6%, university degree 41.8% Employment: full‐time 33.8%, part‐time 17.7%, not working 46.9% Lifetime experience of physical violence by male partner: 20 (5.8%); interview 8 (4.8%); questionnaire 11 (6.8%)
Interventions	Intervention group Face‐to‐face screening using the 7‐item Japanese VAWS with brief counselling and a community resource card on 3 occasions Control group Women in the questionnaire group self completed the VAWS in an antenatal clinic interview room where the community resource cards were available on 3 occasions
Outcomes	Primary outcome Identification (from screen questionnaires) Secondary outcomes Comfort level Need to consult with the nurse after screening (all participants completed a questionnaire immediately after the intervention)
Notes	Funding: Grant‐in‐Aid for COE (Centre of Excellence) Research, provided by the Ministry of Education, Culture, Sports, Science and Technology of Japan
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Researchers "used a random number table in blocks of four to ensure that approximately equal numbers of women were allocated to each group"
Allocation concealment (selection bias)	Low risk	Although it was indicated that numbered, sealed envelopes were used, it was unclear whether opaque envelopes were used. However, since there was no clear intervention/comparison group, the likelihood that selection bias was introduced is low
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	The researchers indicate "because of the nature of the screening methods, participants could not be blinded to the group assignment." However any such bias was likely distributed equally across the 2 groups. Although the extent of the knowledge about participants' assignment, especially given the repeat visits among personnel, is unclear it is unlikely to have influenced the outcomes differentially in the groups
Blinding of outcome assessment (detection bias) All outcomes	Low risk	There was no blinding of outcome assessment; however, the outcome measurement is not likely to be differentially influenced in the 2 groups by lack of blinding as there was not a clear intervention or comparison group. Also the "same researcher performed the allocation procedure and data analysis"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates were low and balanced in the 2 groups (intervention group 10.3%; control group 8.6%). 2 people in the interview group refused to continue compared to 0 in the questionnaire group
Selective reporting (reporting bias)	Low risk	Primary and secondary outcomes reported as specified in protocol. The trial was registered (UMIN‐CTRC000000353)
Other bias	High risk	"Measurements of primary and secondary outcomes had psychometric property limitations"