Hou 2010.
| Methods | Individual randomised controlled trial. Estimated an average of 2.6 missed pills per cycle in the control group, and that a sample size of 68 would be required to detect a 1.6 pill improvement with standard deviation of 2 pills, with 90% power at a 0.05 level of significance, anticipating 15% loss to follow‐up | |
| Participants | 103 women enrolled to the study and 82 randomly assigned after a 1 month run‐in period. 82 sexually active females electing to start using OC, seeking care at Planned Parenthood League of Massachusetts, USA. Mean age of 22 years (range 18 to 31) | |
| Interventions | Control group: routine care according to standard clinic protocol (not stated) during 1 month run‐in period. Women in the control group did not receive text message reminders Study authors reported a high rate of reminder system use in the control group, particularly electronic systems such as cell phone alarms that mimicked the study intervention Intervention group: routine care according to standard clinic protocol (not stated) during 1 month run‐in period plus an automated daily text message aiming to improve OC adherence, “Please remember to take your birth control pill,” sent at a designated time chosen by the participant over the 3 month study period | |
| Outcomes | Number of missed pills per cycle (assessed over 3 months) assessed with electronic monitoring device and patient diary | |
| Behaviour change techniques | As defined by study authors: not described According to Abraham and Michie's typology: 3 behaviour change techniques used (see Table 2) |
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| Notes | Loss to follow‐up: 12% intervention and 10% control | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated randomisation |
| Allocation concealment (selection bias) | Low risk | Sequentially numbered, opaque, sealed envelopes |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | No blinding possible; outcome may have been influenced by lack of blinding. Increased use of reminders in the control group suggests that allocation to intervention or control group may have altered behaviour |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Investigator blinded |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Reason for missing data (mechanical and technological issues) unlikely to be related to true outcome |
| Selective reporting (reporting bias) | Unclear risk | Primary and secondary outcomes stated in the clinicaltrials.gov entry, but insufficient detail on prespecified measurements and subgroup analyses |
| Other bias | Low risk | Study appears to be free of other sources of bias (electronic medication monitor used to assess outcome) |