The following section presents:

  • a data review, consisting of brief summary statements on key points presented at the workshop;

  • the subcommittee's analysis of those lessons learned that it considered most crucial for the future; and

  • areas for consideration and action.

DATA REVIEW

Efficacy

Data were presented from two 5-year-long studies of major short-to medium-term side effects of implant contraceptives not identified in clinical trials: the Postmarketing Surveillance of Norplant led by WHO and pre-introductory studies led by the Population Council. The evidence from those studies was that both Norplant and the two-rod levonorgestrel implant system are highly efficacious, with failure rates under 1 percent per year, thus providing reversible contraceptive protection essentially equal to that of permanent methods, that is, tubal ligation and vasectomy.

Safety

As with all hormonal methods, the contraceptive implant is unsuitable for some women and those contraindications are detailed in its labeling. The Postmarketing Surveillance and Population Council studies found serious adverse events to be extremely rare among implant users over 5 years of study and concluded that, in the settings where those studies were carried out, the method proved to be safe and well-tolerated.

The studies presented at the workshop on the biocompatibility of the polymer known as "silicone rubber" used in the implant produced the following information. First, while the capsules do provoke a typical local foreign-body reaction, the character of the biomaterial and its interface with tissue are not associated with pathological problems. Second, the silicone gel in breast implants is not the same, chemically or biologically, as the silicone rubber used in Norplant, and there are no data that indicate that the silicone elastomer used in Norplant acts as an adjuvant that could potentiate autoimmune disease.

A question that has been asked about the safety of the hormonal implant is whether its progesterone-like effect might, in human beings, produce the same thinning of vaginal epithelium and increased transmission of immunodeficiency virus effected in a monkey model. The report to the workshop was that at present, the quality of the available data does not permit any such conclusions but that until better human studies become available, clinical management of high-risk clients should emphasize protection from sexually transmitted infections through condom



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