| Methods |
Randomized controlled trial without blinding. The method of randomization and use of allocation concealment are not described. We were unable to reach the authors. |
| Participants |
300 women aged 15 to 35 years who did not use oral contraceptives in the month prior to the study at 5 sites in Norway. The participants group had a high rate of abortus provocatus. Exclusion criteria were a history of thrombosis or thrombophlebitis, liver‐disease, cancer, history of herpes gestationis, pregnancy, hypertension and oral contraceptive use in the month prior to 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=150) [Trinordiol] versus
monophasic levonorgestrel/ethinylestradiol (150 μg LNG and 30 μg EE for 21 days, N=150) [Follimin]. |
| Outcomes |
Primary outcome measures are: pregnancy; cycle control; side effects; continuation rate and reason for discontinuation. Use of a patient diary to collect data on side effects and cycle control. The report does not describe the definitions of spotting and breakthrough bleeding. Limited information on outcome measures. |
| Notes |
The report does not provide an a priori hypothesis or a sample size or power calculation. Study duration: 12 cycles. 45 women in the triphasic group and 44 women in the monophasic group discontinued early. Little information concerning the number and reasons for discontinuation. The report does not describe the number of women lost to follow up or excluded because of protocol violations. Analysis not according to intent‐to‐threat principle. Cycles with incorrect pill‐intake were excluded from the analysis. The paper does not report information on support. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
No information |
