20   g versus >20   g XXXX combined oral contraceptives for contraception.

@entity172 @entity548 @entity2082 @entity1871 @entity1867 @entity2588
BACKGROUND: Concern about @entity172 -related adverse effects has led to progressive reductions in the @entity172 dose in combination oral contraceptives (COCs). However, reducing the amount of @entity172 to improve safety could result in decreased contraceptive effectiveness and unacceptable changes in @entity548 patterns. OBJECTIVES: To test the hypothesis that COCs containing  <= 20  g @entity2082 (EE) perform similarly as those containing > 20  g in terms of contraceptive effectiveness, @entity548 patterns, discontinuation, and side effects. SEARCH STRATEGY: We searched CENTRAL, MEDLINE, EMBASE, POPLINE, ClinicalTrials.gov, and ICTRP, and examined references of eligible trials. Initially, we wrote to oral contraceptive manufacturers to identify trials. SELECTION CRITERIA: English-language reports of randomized controlled trials were eligible that compare a COC containing  <= 20  g EE with a COC containing > 20  g EE. We excluded studies where the interventions were designed to be administered for less than three consecutive cycles or to be used primarily as treatment for non-contraceptive conditions. Trials had to report on contraceptive effectiveness, @entity548 patterns, trial discontinuation due to @entity548 -related reasons or other side effects, or side effects to be included in the review. DATA COLLECTION AND ANALYSIS: One author evaluated all titles and abstracts from literature searches to determine whether they met the inclusion criteria. Two authors independently extracted data from studies identified for inclusion. We wrote to the researchers when additional information was needed. Data were entered and analyzed with RevMan. MAIN RESULTS: No differences were found in contraceptive effectiveness for the 13 COC pairs for which this outcome was reported. Compared to the higher- @entity172 pills, several COCs containing 20  g EE resulted in higher rates of early trial discontinuation (overall and due to adverse events such as @entity548 ) as well as increased risk of @entity548 disturbances (both @entity2588 or infrequent @entity548 and irregular, prolonged, frequent @entity548 , or @entity1867 or spotting). AUTHORS' CONCLUSIONS: While COCs containing 20  g EE may be theoretically safer, this review did not focus on the rare events required to assess this hypothesis. Data from existing randomized controlled trials are inadequate to detect possible differences in contraceptive effectiveness. Low-dose @entity172 COCs resulted in higher rates of @entity548 pattern disruptions. However, most trials compared COCs containing different progestin types, and changes in @entity548 patterns could be related to @entity1871 type as well as @entity172 dose. Higher follow-up rates are essential for meaningful interpretation of results.
