Effects of initiating a contraceptive implant on subsequent condom use: A randomized controlled trial.

OBJECTIVE

To evaluate whether initiation of a contraceptive implant, a method of long-acting reversible contraception, reduces condom use, as measured by a biomarker of recent semen exposure [prostate-specific antigen (PSA)].

STUDY

DESIGN

We conducted a randomized controlled clinical trial in which 414 Jamaican women at high risk for sexually transmitted infections (STIs) attending family planning clinics received the contraceptive implant at baseline ("immediate" insertion arm, N=208) or at the end ("delayed" insertion arm, N=206) of a 3-month study period. Participants were tested for PSA at baseline and two follow-up study visits and were asked about their sexual activity and condom use.

RESULTS

At baseline, 24.9% of women tested positive for PSA. At both follow-up visits, the prevalence of PSA detection did not significantly differ between the immediate versus delayed insertion arm [1-month: 26.1% vs. 20.2%, prevalence ratio (PR)=1.3, 95% confidence interval (CI)=0.9-1.9; 3-month: 25.6% vs. 23.1%, PR= 1.1, 95% CI=0.8-1.6]. The change in PSA positivity over the three study visits was not significantly larger in the immediate arm compared to the delayed arm (1-sided p-value of .15).

CONCLUSIONS

Contraceptive implants can be successfully introduced into a population at high risk of unintended pregnancy and STIs without a biologically detectable difference in unprotected sex in the short term. This information strengthens the evidence to support promotion of implants in such populations and can help refine counseling for promoting and maintaining use of condoms among women who choose to use implants.

IMPLICATIONS: Sex unprotected by a condom was not higher over 3 months in women receiving a contraceptive implant, compared with those not receiving the implant.