Oral Contraceptive Use and Bone Density in Young Women

描述（由申请人提供）：对于使用口服避孕药（OCs）的1000多万美国妇女来说，关于口服避孕药对健康影响的明确证据是一个主要的公共卫生问题。最近的几项研究表明，目前的OC配方可能会抑制年轻女性骨量峰值的增加。然而，这种可能性还没有得到充分的评估，特别是在青少年中使用OC，这是最积极获得骨骼的群体。本应用侧重于对年轻女性使用骨臼对骨骼的影响进行全面评估。我们考虑了不同的骨骼部位，不同的使用时间和不同的OC雌激素含量。重要的是，据我们所知，这将是第一个记录OC停药后骨密度（BMD）变化的前瞻性研究。

DESCRIPTION (provided by applicant): For the more than 10 million US women using oral contraceptives (OCs), clear evidence regarding the health effects of OCs is a major public health concern. Several recent studies suggest that current OC formulations may act to suppress peak bone mass accrual in young women. However, this possibility has not been fully evaluated, particularly with regard to OC use among adolescents, the group most actively gaining bone. This application is focused on a thorough evaluation of the impacts of OC use on bone in young women. We include consideration of different skeletal sites, varying durations of use, and differing OC estrogen content. Importantly, this would be the first prospective study to our knowledge to document changes in bone mineral density (BMD) after OC discontinuation. We propose a prospective epidemiologic study of the effects on bone of new and ongoing OC use and of OC discontinuation in a cohort of adolescent and young adult women. The cohort (n=600) will be recruited from a defined population of HMO enrollees between the ages of 14 and 30, with 300 participants aged 14-18 years and 300 aged 19-30. Each age group will include 200 OC users and 100 comparison women. We will evaluate possibly different effects from a low-dose (20 mcg EE) and a higher-dose (35 mcg EE) formulation. The HMO's automated pharmacy and membership files will be used to select women who are new and ongoing users of OCs and to randomly select comparison women who are not using hormonal contraception, frequency matching on age and clinic. Participants will be followed longitudinally for 24-36 months. The primary outcome, bone mineral density, will be measured every 6 months at selected anatomic sites (hip, spine, whole body) using dual-energy x-ray absorptiometry. In our work to date investigating the association between injectable contraception and BMD in adolescents and young adult women, we have achieved excellent participant recruitment and retention with similar methods and have developed relevant measurement and analytic strategies. OC use is highest among sexually active adolescents and women in their 20s. These are also women who are actively gaining bone. Given the increasing public health importance of osteoporosis and the prevalence of OC exposure at a crucial stage of growth, focused evaluation of the potentially adverse effects of OC use on the skeletal health of these young women--and their possible amelioration upon cessation of this exposure--is essential.