Department of Medicine, Center for Pharmacoepidemiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Maternity BB Stockholm, Danderyds Hospital, Stockholm, Sweden.
Acta Obstet Gynecol Scand. 2019 Jul;98(7):937-943. doi: 10.1111/aogs.13564. Epub 2019 Mar 14.
The objective was to investigate the Pearl index for ectopic pregnancy in women using the levonorgestrel intrauterine system (LNG-IUS) at the time of conception.
This was a substudy of a hospital-based historical cohort including women with an ectopic pregnancy diagnosed in 4 referral hospitals in Stockholm, Sweden between December 2013 and April 2017. Study participants and type of contraception at time of conception were identified through the electronic medical chart system. Cases were defined as women with LNG-IUS 13.5 or 52 mg in situ at the time of diagnosis of ectopic pregnancy who had their LNG-IUS inserted 1 January 2014 or later. Outcome was defined as the incidence rate for ectopic pregnancy during use per 100 woman-years (Pearl index) with 95% confidence interval (95% CI).
The study includes 35 cases with LNG-IUS 13.5 mg and 13 cases with LNG-IUS 52 mg, which occurred in 18 488 (13.5 mg) and 50 246 (52 mg) exposed woman-years. Pearl index for ectopic pregnancy was estimated at 0.19 (95% CI 0.15-0.28) for LNG-IUS 13.5 mg and to 0.006 (95% CI 0.00-0.01) for LNG-IUS 52 mg. The most cases for the LNG-IUS 13.5 mg (n = 26; 74%) occurred during the first year of use with a corresponding Pearl index at 0.23 (95% CI 0.14-0.35).
The absolute risk of ectopic pregnancy during the use of LNG-IUS remains low. Our method may underestimate as well as overestimate the Pearl index for ectopic pregnancy. The findings underline the importance of identifying risk factors for ectopic pregnancy at insertion, and to rule out ectopic pregnancy for all women presenting with abdominal discomfort during the use of LNG-IUS. Longer observation periods and prospective studies in a general population are a priority for further research.
本研究旨在探讨在妊娠时使用左炔诺孕酮宫内节育系统（LNG-IUS）的妇女异位妊娠的 Pearl 指数。
这是一项基于医院的历史队列研究的子研究，纳入了 2013 年 12 月至 2017 年 4 月期间在瑞典斯德哥尔摩的 4 家转诊医院诊断为异位妊娠的女性。通过电子病历系统确定了研究参与者和妊娠时的避孕类型。病例定义为在诊断为异位妊娠时体内有 13.5 或 52mgLNG-IUS，且其 LNG-IUS 于 2014 年 1 月 1 日或之后插入的女性。结果定义为每 100 名妇女年（Pearl 指数）的异位妊娠发生率及其 95%置信区间（95%CI）。
该研究包括 35 例使用 13.5mgLNG-IUS 和 13 例使用 52mgLNG-IUS 的病例，分别发生在 18488 名（13.5mg）和 50246 名（52mg）暴露于 LNG-IUS 的女性年中。LNG-IUS 13.5mg 的异位妊娠 Pearl 指数估计为 0.19（95%CI 0.15-0.28），LNG-IUS 52mg 的异位妊娠 Pearl 指数估计为 0.006（95%CI 0.00-0.01）。LNG-IUS 13.5mg 中最多的病例（n=26；74%）发生在使用的第一年，相应的 Pearl 指数为 0.23（95%CI 0.14-0.35）。
LNG-IUS 使用期间异位妊娠的绝对风险仍然较低。我们的方法可能会低估和高估异位妊娠的 Pearl 指数。这些发现强调了在插入时识别异位妊娠风险因素的重要性，并排除所有在使用 LNG-IUS 期间出现腹部不适的妇女的异位妊娠。进一步研究的优先事项是进行更长的观察期和在一般人群中的前瞻性研究。
