CHICAGO (EGMN) – Longer oral contraceptive use plus parity were protective against the development of endometriosis in a retrospective cohort study of young women in the Australian Longitudinal Study on Women’s Health.
Researchers analyzed data at four time points over a 10-year-period from a subset of 9,427 women aged 18-23 years at the time of entry in the ALSWH. The study is prospectively following 40,000 women over a 20-year period to better estimate the association between oral contraceptive (OCP) use and risk of endometriosis.
A total of 514 new endometriosis cases occurred over the 10 years, with an incidence rate of 670 per 100,000 person-years of risk, Dr. Frank Tu and his associates reported in a poster at the annual meeting of the International Pelvic Pain Society.
Univariate analysis revealed that immediate prior OCP use was a risk factor for endometriosis. In bivariate analysis, however, OCP use was a risk factor for endometriosis in nulliparous women but not in parous women.
The researchers then conducted a multivariate Cox regression analysis that adjusted for such confounders as body mass index (BMI), parity, geographical location, OCP use for other reasons, urinary pain, marital status, SF-36 (Short-Form–36) pain score, dysmenorrhea, total years of OCP use, and its interaction with parity.
In this analysis, nulliparous women with prior exposure to OCPs had a dose-dependent increased risk of developing endometriosis; however, prior exposure to OCPs was protective among parous women, reported Dr. Tu of the NorthShore University Health System in Chicago.
Compared with nulliparous women who never used OCPs, the risk for a subsequent diagnosis of endometriosis was 1.8 times higher in nulliparous women who had used OCPs for less than 5 years, and 2.3 times higher in those with at least 5 years of OCP use.
In contrast, parous women with 5 years or more of OCP exposure had a significant 59% reduced risk of endometriosis, compared with those who never used OCPs. The risk of endometriosis was reduced 55% in parous women with less than 5 years of OCP, but this did not reach statistical significance.
“While our study revealed that longer OCP use plus parity were protective against endometriosis, rigorous mechanistic studies are needed to validate if use of exogenous sex hormones is a risk factor for the development of endometriosis and pelvic pain conditions among nulliparous women,” the authors concluded.
At midstudy, endometriosis patients were significantly more likely than controls to report having heavy menstrual periods “sometimes or often” (46% vs. 25%), having constipation (19% vs. 13%), painful urination (17% vs. 8%), severe period pain (64% vs. 38%), low back pain (48% vs. 37%), and depression (4% vs. 2%).
Roughly two-thirds of cases and controls had an acceptable BMI of 18.5-25 kg/m2 (68% vs. 69%), one-third had some post–high school education (29% vs. 30%), and few were married (10% vs. 9%).
Dr. Tu disclosed no conflicts of interest.
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芝加哥(EGMN)——芝加哥北岸大学医疗卫生系Frank Tu博士及其同事在国际盆腔疼痛学会年会壁报展示中称，经产妇长期服用口服避孕药可预防子宫内膜异位症的发生。
研究者对9,427例年轻女性(入组年龄为18~23岁)10年随访期间的4个时间点的资料进行回顾性队列研究，以评估口服避孕药(OCP)的使用与子宫内膜异位症风险的相关性。
结果显示，10年间共发生514例子宫内膜异位症，发生率为670例/10万(人·年)。单变量分析显示，近期服用OCP是子宫内膜异位症的风险因素，但双变量分析表明，服用OCP是未产女性而非经产女性子宫内膜异位症的风险因素。调整诸如体重指数、经产状况、地理位置、其他原因服用OCP、尿道疼痛、婚姻状况、SF-36疼痛量表、痛经、服用OCP总年数及其与经产关系等混淆因素后的多变量Cox回归分析显示，与从未服用OCP的未产女性相比，服用OCP少于5年的未产女性子宫内膜异位症风险高出1.8倍，而服用OCP至少5年的未产女性风险高出2.3倍；与之相反，OCP暴露5年或以上的经产女性子宫内膜异位症风险比从未服用OCP者降低59%，OCP暴露少于5年的经产女性风险降低55%，但后者无统计学意义。
研究表明，先前OCP暴露的未产女性子宫内膜异位症发生风险呈剂量依赖性增加，然而，先前较长时间OCP暴露对经产女性则具有保护作用。
研究者声称无利益冲突。
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