| Methods |
Randomized controlled trial with blinding of investigators and participants. Allocation concealment by use of numbered pharmacy packages, blinding by repackaging the pills. The method of randomization is not described. Communication with the authors revealed no extra information. |
| Participants |
1800 women at 18 sites in the Philippines. The report does describe the inclusion and exclusion criteria for the study. Switchers were included in the study. 27% to 32% of the participating women lactated at the time of admission. |
| Interventions |
Triphasic levonorgestrel/ethinylestradiol (50‐75‐125 μg LNG and 30‐40‐30 μg EE in a 6/5/10 days regimen, N=601) [Trinordiol] versus
monophasic norethindrone/ethinylestradiol (400 μg NET and 35 μg EE for 21 days, N=599) [Micropil] versus
monophasic levonorgestrel/ethinylestradiol (150 μg LNG and 30 μg EE for 21 days, N=600) [Nordette]. |
| Outcomes |
Primary outcome measures are: pregnancy; side effects; cycle control; continuation rates and reasons for discontinuation. Use of menstrual diary cards to collect data on cycle control. Data on side effects were recorded if reported spontaneously. Information on side effects was specifically asked at discontinuation or method change. Breakthrough bleeding was defined as intermenstrual bleeding that required the use of sanitary protection, and spotting as intermenstrual bleeding which required no use of pads. |
| Notes |
The report does not provide an a priori hypothesis or a sample size or power calculation. Study duration: 12 cycles. 165 women in the triphasic group, 192 women in the NET monophasic group and 151 women in the LNG monophasic group discontinued early. The reasons for discontinuation are described. 13 participants in the triphasic group, 9 participants in the NET monophasic group and 16 participants in the monophasic LNG group were lost to follow up. 11 women in triphasic group, 12 women in the NET monophasic group and 8 women in the LNG monophasic group were withdrawn because of protocol violations. Analysis not according to intention‐to‐treat principle. The trial was supported by United Nations Population Fund and by the manufacturers of the triphasic levonorgestrel/ethinylestradiol and monophasic levonorgestrel/ethinylestradiol pill (Wyeth‐Ayerst) and monophasic norethindrone/ethinylestradiol pill (Pascual Laboratories). |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
Allocation concealment by use of numbered pharmacy packages |
