| Methods |
Randomized controlled trial. The method of randomization and the use of blinding are not described. Communication with the author indicated a computer‐generated random allocation sequence and blinding of participants and investigators. Method of randomizing is unclear. |
| Participants |
862 women at 12 sites in Sweden. Inclusion criteria were that women had to fulfill the current recommendations for oral contraceptive use. Limited information on baseline characteristics. Switchers were included in the study. |
| Interventions |
Triphasic levonorgestrel/ethinylestradiol (50‐75‐125 μg LNG and 30‐ 40‐30 μg EE in a 6/5/10 days regimen, N=210 for 6 cycles of whom N=89 continued for an additional 6 cycles) [Trionetta 21] versus
triphasic levonorgestrel/ethinylestradiol (50‐75‐125 μg LNG and 30‐40‐30 μg EE in a 6/5/10 days regimen and 7 days of placebo tablets, N=207 for 6 cycles of whom N=93 continued for an additional 6 cycles) [Trionetta 28] versus
monophasic levonorgestrel/ethinylestradiol (150 μg LNG and 30 μg ethinylestradiol, N=418 for 6 cycles of whom N=189 continued for an additional 6 cycles) [Neovletta]. |
| Outcomes |
Primary outcomes measures are: pregnancy; side effects; cycle control; continuation rate and reasons for discontinuation. Use of diary cards to collect data on pill‐intake errors and cycle control. Breakthrough bleeding was defined as intermenstrual bleeding which required the use of sanitary protection and spotting as all other cases. Data on side effects were recorded if reported spontaneously. |
| Notes |
The report does not provide an a priori hypothesis or a sample size or power calculation. Study duration: 6 and 12 cycles. 67 women in the triphasic group and 60 women in the monophasic group discontinued early in the 1 to 6 cycles trial period. 26 women in the triphasic group and 24 women in the monophasic group discontinued early in the 7 to 12 cycles trial period. Little information concerning the number and reasons for discontinuation. 27 women entered in the trial are not included in the analysis because they were lost to follow up. The report does not describe withdrawals because of protocol violations. Analysis not according to intention‐to‐treat principle. The trial was supported by the manufacturer of the studied monophasic and triphasic levonorgestrel/ethinylestradiol pills (Schering). |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
Report does not mention the use of allocation concealment. Communication with the author indicated allocation concealment by numbered pharmacy packages. |
