Continuous or extended cycle vs. cyclic use of combined oral contraceptives for contraception

Background The avoidance of menstruation through extended or continuous administration (greater than 28 days of active pills) of combination oral contraceptives (COCs) has gained legitimacy through its use in treating endometriosis, dysmenorrhea, and menstruation- associated symptoms. Avoidance of menstruation through continuous use of COCs for reasons of personal preference may have additional advantages to women, including improved compliance, greater satisfaction, fewer menstrual symptoms, and less menstruation- related absenteeism from work or school. Objectives To determine the differences between COCs dosed continuously (greater than 28 days of active pills) compared with traditional cyclic dosing (21 days of active pills and 7 days of placebo). Our hypothesis was that continuously administered COCs have equivalent efficacy and safety but improved bleeding profiles, amenorrhea rates, adherence, continuation, participant satisfaction, and menstrual symptoms compared with cyclic COCs. Search strategy We searched computerized databases (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, POPLINE, LILACS) for trials using continuous or extended COCs during the years 1966 to 2005. We also searched the references in review articles and publications identified for inclusion in the protocol. Investigators were contacted regarding additional references. Selection criteria All randomized controlled trials in any language comparing continuous (greater than 28 days of active pills) versus traditional cyclic administration (21 days of active pills and 7 days of placebo) of COCs for contraception. Data collection and analysis Titles and abstracts identified from the literature searches were assessed for potential inclusion. Data were extracted onto data collection forms and then entered into RevMan 4.2. Peto odds ratios with 95% confidence intervals were calculated for all outcomes for dichotomous outcomes. Weighted mean difference was calculated for continuous outcomes. The trials were critically appraised by examining the following factors: study design, blinding, randomization method, group allocation concealment, exclusions after randomization, loss to follow-up, and early discontinuation. Because the included trials did not have a standard treatment ( type of pill and time length for continuous dosing), we could not aggregate data into meta-analysis. Main results Six randomized controlled trials met our inclusion criteria. Study findings were similar between 28-day and extended cycles in regard to contraceptive efficacy (i.e., pregnancy rates) and safety pro files. When compliance was reported, no difference between 28-day and extended cycles was found. Participants reported high satisfaction with both dosing regimens, but this was not an outcome universally studied. Overall discontinuation and discontinuation for bleeding problems were not uniformly higher in either group in most studies. The few studies that reported menstrual symptoms found that the extended cycle group fared better in terms of headaches, genital irritation, tiredness, bloating, and menstrual pain. Five out of the six studies found that bleeding patterns were either equivalent between groups or improved with continuous-dosing regimens. Endometrial lining assessments by ultrasound were done in a small number of participants but all endometrial stripe measurements were less than 5 mm. Authors' conclusions Evidence from existing randomized control trials comparing COCs given continuously (greater than 28 days of active pills) to traditional monthly cyclic dosing (21 days of active pills and 7 days of placebo) is of good quality. However, the variations in type of pill and time length for continuous dosing make direct comparisons between regimens impossible. Future studies should choose a previously described type of pill and dosing regimen. More attention needs to be directed towards participant satisfaction and menstruation-associated symptoms.