A Cochrane review «»1 «French R, Van Vliet H, Cowan F, Mansour D, Morris ...»1 included 25 studies. 9 trials were included in meta-analyses, four comparing LNG-20 IUSs with non-hormonal IUDs, one comparing the LNG-20 IUS with Norplant-2, one comparing the LNG-20 IUS with oral contraceptives (COCs), and three comparing Progestasert with non-hormonal IUDs.
There was no significant difference in the pregnancy rates between LNG-20 and IUD >250mm2 or COC users. There was a significantly lower risk of pregnancy when the LNG-20 IUS was compared to IUDs ≤ 250 mm2. Women using the LNG-20 IUS were more likely to experience amenorrhoea and device expulsion than women using IUDs >250mm2. LNG-20 users were significantly more likely than all the IUD users to discontinue because of hormonal side effects and menstrual disturbance. When compared to Norplant-2, the LNG-20 users were significantly more likely to experience amenorrhoea and oligomenorrhoea, but significantly less likely to experience prolonged bleeding and spotting. No other significant differences were observed. The contraceptive effectiveness of Progestasert was significantly better than non-medicated IUDs, but no difference was observed when compared to IUDs ≤ 250mm2.
LNG-20 IUS did not have impact upon breastfeeding performance or the growth and development of breastfed infants in lactating women (1 trial, n=320) nor did the device have an adverse effect on glucose metabolism among insulin-dependent diabetic women (1 trial, n=60).
A prospective observational cohort study «O'neil-Callahan M, Peipert JF, Zhao Q et al. Twent...»2 (The Contraceptive CHOICE Project, n= 9 256) that provided no-cost contraception to women in the USA assessed 24-month continuation rates of all reversible contraceptive methods. The project promoted the use of long-acting reversible contraception (LARC: IUDs and implants). Twenty-four month continuation rates for LARC and non-LARC methods were 77% and 41%, respectively (n=6 153). Continuation at 24-months for the levonorgestrel intrauterine system (LNG-IUS) and the copper IUD were the highest reported and similar 79%, and 77%, respectively. The implant continuation rate was significantly lower (69%, P<.001) compared with IUDs at 24 months. There was no statistically significant difference in 24-month continuation rates among the 4 non-LARC methods COC 43%, patch 40%, ring 41%, depot medroxyprogesterone acetate 38%; P=.72). Participants with a LARC method were at significantly lower risk of contraceptive method discontinuation (adjusted hazard ratio 0.29, 95% confidence interval 0.26-0.32) compared with women using a non-LARC method.
Another part of the The Contraceptive CHOICE Project «Winner B, Peipert JF, Zhao Q et al. Effectiveness ...»3 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 LARC: 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 prospective cohort study «McNicholas C, Swor E, Wan L et al. Prolonged use o...»4 evaluated the effectiveness of the contraceptive implant and the 52-mg hormonal intrauterine device in women using the method for 2 years beyond the current approved 3 and 5 years of use, respectively. There have been no documented pregnancies in implant users during the 2 years of postexpiration follow-up (n=291 with 444 woman-years). Two pregnancies have been reported in levonorgestrel intrauterine device users (n=496 with 696.9 woman-years). The failure rate in the sixth year of use of the levonorgestrel intrauterine device is calculated as 0.25 (95% CI 0.04 to 1.42) per 100 woman-years; failure rate during the seventh year is 0.43 (95% CI 0.08 to 2.39) per 100 woman-years. Among implant users the median etonogestrel level was 207.7 pg/mL (range 63.8-802.6 pg/mL) at the time of method expiration, 166.1 pg/mL (range 67.9 25.0-470.5 pg/mL) at the end of the fourth year, and 153.0 pg/mL (range 72.1-538.8 pg/mL) at the end of the fifth year. Median etonogestrel levels were compared by body mass index at each time point and a statistical difference was noted at the end of 4 years of use with overweight women having the highest serum etonogestrel (195.9; range 25.0-450.5 pg/mL) when compared to normal (178.9; range 87.0-463.7 pg/mL) and obese (137.9; range 66.0-470.5 pg/mL) women (P = .04).
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