An integrated analysis of vaginal bleeding patterns in clinical trials of Implanon®

The vaginal bleeding patterns observed during the use of the single-rod progestin-only implant, Implanon®, compared with those seen during the use of the six-capsule implant, Norplant®, have been analyzed. The acceptability of these bleeding patterns was also assessed. An integrated analysis of 13 different trials was done, studying reference periods (RP) of 90 days. These trials included totals of 1716 Implanon users and 689 Norplant users. There were statistically significant lower mean values over RP 2-8 (the range over RP 2-8 is presented) for Implanon, for the number of bleeding-spotting days (15.9-19.3 vs. 19.4-21.6; p = 0.0169), the number of bleeding days (7.5-10.0 vs. 11.7-13.1; p <0.001), and the number of bleeding-spotting episodes (2.2- 2.7 vs. 3.1-3.3; p <0.0001). The bleeding patterns of Implanon users appeared to be more variable than those observed with Norplant: Implanon users had more amenorrhea, and slightly more infrequent bleeding, frequent bleeding, and prolonged bleeding than Norplant users. The difference was only statistically significant for amenorrhea (17.9%-24.8% with Implanon compared with 2.0%-7.0% for Norplant over RP 2-8). There were no statistically significant differences in the acceptability of the two products as indicated by the discontinuation rates, which were 30.2% and 0.9% in Europe and Southeast Asia, respectively, for Implanon, and 22.5% and 1.4%, respectively, in the two regions, for Norplant. The individual bleeding pattern was not predictable. However, in general, it can be stated that women initially without bleeding or with infrequent bleeding have only a small chance of becoming frequent bleeders, and vice versa. Dysmenorrhea clearly improved during use of both Implanon and Norplant. Neither Implanon nor Norplant caused anemia.