| Methods |
Randomized controlled trial without blinding. The method of randomization is not described. Communication with the author indicated an allocation sequence in balanced blocks of four. The method of randomizing the blocks of 4 is unclear. |
| Participants |
948 women at sites in 6 European countries. The report does not provide inclusion/exclusion criteria for the study and scarcely describes the baseline demographics. Communication with the authors provided the inclusion/exclusion criteria. Inclusion criteria were healthy, fertile women with a regular cycle and normally exposed to the risk of pregnancy. Exclusion criteria were history of thromboembolic disease, thrombophlebitis, disturbance of liver function, jaundice or a history of jaundice in pregnancy, mammary carcinoma, estrogen‐dependent tumor, undiagnosed genital bleeding, sickle‐cell anemia, porphyria cutanea tarda, cardiovascular disease, treatment with rifampicin, tetracyclines, phenylhydantoin and phenobarbitone, no spontaneous menstruation postpartum or postabortal, breastfeeding. |
| Interventions |
Triphasic levonorgestrel/ethinylestradiol (50‐75‐125 μg LNG and 30‐40‐30 μg EE in a 6/5/10 days regimen, N=473 for 6 cycles of whom N=38 continued for an additional 6 cycles) [no brand name described] versus
monophasic desogestrel/ethinylestradiol (150 μg DSG and 30 μg EE for 21 days, N=475 for 6 cycles of whom N=54 continued for an additional 6 cycles) [Marvelon]. |
| Outcomes |
The primary outcome measures are: pregnancy; side effects; cycle control; discontinuation rates. Use of a record to collect data on cycle control and side effects. Withdrawal bleeding was defined as bleeding which begins in the tablet‐free period; spotting as scanty bleeding outside the tablet‐free period that does not require any hygienic measures or at most one sanitary pad per day; and breakthrough bleeding as bleeding that is not spotting and which cannot be considered as withdrawal bleeding. Report describes outcome measures unclearly. Communication with the author revealed that there were 3 pregnancies instead of the reported 2. |
| Notes |
The report does not provide an a priori hypothesis or a sample size or power calculation. Study duration: 6 and 12 cycles. The report does not describe the number and reasons for discontinuation. Communication with the author gave information that 67 women in both groups discontinued early in the 1 to 6 cycles trial period and 2 women in both groups discontinued early in the 7 to 12 cycles trial period. Three women in the triphasic group and two women in the monophasic were withdrawn because of protocol violations in the first trial period. No women were withdrawn because of protocol violations in the second trial period. The number of women lost to follow up was not clear. Analysis not according to intent‐to‐treat principle. The trial was supported by the manufacturer of the studied monophasic desogestrel/ethinylestradiol pill (Organon). |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
High risk |
Not mentioned in report. Communication with the author indicated no concealment of the allocation sequence. |
