A Cochrane review [Abstract] 1 included 4 studies with a total of 5 939 subjects. All IUDs had low pregnancy rate at 3 year. The subjects were randomised to either a frameless device or TCu 380A, with a total experience of 23 180 women-years. The two earlier trials used a prototype introducer and there was a higher expulsion rate at one year. However, between two and six years in the large WHO trial the risk of pregnancy was lower with the frameless device (RR 0.53, 95% CI 0.32 to 0.91). In a recent trial using GyneFix with a new introducer early expulsions and pregnancies were not statistically different from the control device. Removal rates for excessive bleeding and/or pain were no different between the devices (RR 0.92, 95% confidence intervals 0.74 to 1.14, at one year and 1.13, 95% CI 0.93 to 1.37, at six years). There was a tendency towards fewer removals for pain in early years but no difference at six years (RR 1.13, 95% CI 0.93 to 1.37).
A prospective observational cohort study 2 (The Contraceptive CHOICE Project, n= 9 256) that provided no-cost contraception to women in the USA compared the rate of failure of different contraceptive methods in the overall cohort and in groups stratified according to age (less than 21 years of age vs. 21 years or older). Among the 7 486 participants 334 unintended pregnancies were identified. Women using contraceptive pills, transdermal patch, or vaginal ring had higher rates of unintended pregnancy than those using long-acting reversible contraception (LARC: IUDs and implants): Failure rates for the pills, patch, or ring were 4.8%, 7.8%, and 9.4% in years 1, 2, and 3, respectively; the corresponding rates in the group using IUDs or implants were 0.3%, 0.6%, and 0.9% (P<0.001). The failure rates for depot medroxyprogesterone acetate injection were similar to those for IUDs or implants (0.1%, 0.7%, and 0.7% for years 1, 2, and 3, respectively; P=0.96). The contraceptive failure rate among participants using pills, patch, or ring was 4.55 per 100 participant-years, as compared with 0.27 among participants using LARC (hazard ratio after adjustment for age, educational level, and history with respect to unintended pregnancy, 21.8; 95% confidence interval, 13.7 to 34.9). Among participants who used pills, patch, or ring, those who were less than 21 years of age had a risk of unintended pregnancy that was almost twice as high as the risk among older participants.
A multinational, prospective, non-interventional cohort study 3 of new users of levonorgestrel-releasing intrauterine systems (LNG-IUS) and copper IUDs included 61 448 women in 6 European countries. The copper IUD cohort contained more than 30 different types. Validated 1-year follow-up information for 58 324 users between 18 and 50 years of age (70% using LNG-IUS, 30% using copper IUDs) was collected. A total of 118 contraceptive failures occurred (26 LNG, 92 copper). Both types of IUD were highly effective, with overall Pearl indices of 0.06 (95% CI 0.04 to 0.09 for LNG-IUS and 0.52 (95% CI 0.42 to 0.64) for copper IUDs. The adjusted hazard ratio for LNG-IUS vs. copper IUDs was 0.16 (95% CI 0.10 to 0.25). 21 pregnancies (7 LNG IUS, 14 copper IUD) were ectopic, yielding an adjusted hazard ratio for ectopic pregnancy of 0.26 (95% CI 0.10 to 0.66).
An RCT 4 including 600 women assessed the continuation rate, efficacy, and acceptability of TCu380Ag in three sizes versus TCu380A at 5 years of use. At 5 years of use, Kaplan-Meier survival analysis showed that TCu380Ag compared with TCu380A had a higher continuation rate (45% vs. 35%, P = 0.010) with 100% efficacy each. TCu380Ag had fewer side effects, including heavy menstrual bleeding (16.6% vs. 34.1%, P < 0.001), abdomen pain (12.1% vs. 23.0%, P = 0.001), and expulsions (4.4% vs. 8.7%, P < 0.050), and fewer discontinuations attributable to contraceptive side effects (42.7% vs. 56.9%, P = 0.012). The mini TCu380Ag had the highest continuation rates and least menstrual irregularity (P < 0.050).
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