Background: Knowledge of contraceptive effectiveness is crucial to making an informed choice. The consumer has to comprehend the pros and cons of the contraceptive methods being considered. Choice may be influenced by understanding the likelihood of pregnancy with each method and factors that influence effectiveness.
Objectives: To review all randomized controlled trials comparing strategies for communicating to consumers the effectiveness of contraceptives in preventing pregnancy.
Search strategy: We searched the computerized databases MEDLINE, POPLINE, CENTRAL, PsycINFO, and EMBASE for studies of communicating contraceptive effectiveness. We also examined references lists of relevant articles, and wrote to known investigators for information about other published or unpublished trials.
Selection criteria: We included randomized controlled trials that compared methods for communicating contraceptive effectiveness to consumers. The comparison could be usual practice or an alternative to the experimental intervention.
Data collection and analysis: Data were abstracted by two authors and entered into RevMan. For dichotomous variables, the Peto odds ratio (OR) with 95% confidence intervals (CI) was calculated. For continuous variables, the weighted mean difference (WMD) was computed.
Main results: Five trials met the inclusion criteria. In one study, knowledge gain favored a slide-and-sound presentation versus a physician's oral presentation (WMD -19.00; 95% CI -27.52 to -10.48). Another trial showed a table with effectiveness categories led to more correct answers than one based on numbers [ORs were 2.42 (95% CI 1.43 to 4.12) and 2.19 (95% CI 1.21 to 3.97)] or a table with categories and numbers [ORs were 2.58 (95% CI 1.5 to 4.42) and 2.03 (95% CI 1.13 to 3.64)]. One trial examined contraceptive choice: women in the expanded program were more likely to choose sterilization (OR 4.26; 95% CI 2.46 to 7.37) or use a modern contraceptive method (OR 2.35; 95% CI 1.82 to 3.03). No trial had an explicit theoretical base, but each used concepts from common theories or models.
Authors' conclusions: We have limited evidence about what works to help consumers choose an appropriate contraceptive method. For presenting pregnancy risk data, one trial showed that categories were better than numbers. In another trial, audiovisual aids worked better than the usual oral presentation. Strategies for communicating information should be examined in clinical settings and assessed for effect on contraceptive choice and retention of knowledge. To expand the knowledge base of what works in contraceptive counseling, randomized trials could intentionally use and test theories or models.