ABSTRACT
OBJECTIVE: Sino-implant (II) is a contraceptive implant approved for 4 years of use in China. We evaluated the contraceptive efficacy during the third, fourth and fifth year, and assessed additional pharmacokinetics (PK), safety, and acceptability endpoints. STUDY DESIGN: We enrolled a cohort of 255 current Sino-Implant (II) users entering their third year and a second cohort of 243 users entering their fourth year. We followed these two cohorts for 12 and 24â¯months, respectively. To characterize PK endpoints (i.e. levonorgestrel (LNG), sex hormone binding globulin and free LNG index) over 5 years, we collected blood samples in a subset of 50 participants we followed during the third, fourth and fifth year. We also enrolled small cohorts (nâ¯=â¯20) of Sino-implant (II) users entering their sixth month and second year and followed them each for up to 6 months. Our primary efficacy measures were the pregnancy Pearl Indices during Year 3 and 4. Secondary objectives included assessments of PK, safety, acceptability and efficacy in the fifth year. RESULTS: We recorded four pregnancies, with a higher pregnancy rate during Year 3 [1.34 (95% CI: 0.28-3.93)] than Year 4 [0.44 (95% CI: 0.01-2.47)] or Year 5 [0.00 (95% CI: 0.00-2.02)]. The overall pregnancy rate for the third, fourth and fifth years of product use was 0.63 per 100 WY; 95% CI: (0.17-1.62). Mean LNG concentrations remained well above 200â¯pg/mL (Year 3â¯=â¯280.9; Year 4â¯=â¯233.6; Year 5â¯=â¯270.6). Most participants (93.7%) described their bleeding pattern as acceptable. CONCLUSION: Sino-implant (II) is a highly effective contraceptive method in this population of Chinese women over 5 years. IMPLICATIONS: Sino-implant (II) is a highly effective contraceptive method with an estimated Pearl Index of less than 1% over the third, fourth and fifth years of use in a population of Chinese women of reproductive age.