USPSTF反对绝经后服用维生素D/钙补充剂

美国预防服务工作组(USPSTF) 2月25日在《内科学年鉴》上在线发表的推荐意见指出，基于有关研究结果，维生素D和钙补充剂增加健康绝经后女性肾结石风险且不能预防骨折，反对这类人群服用该类补充剂。
 


Virginia A. Moyer博士在报告中指出，USPSTF特别建议(中度肯定)，反对非住院绝经后女性补充剂量≤400 IU的维生素D和剂量≤1,000 IU的钙。鉴于有关更高剂量补充剂的证据不足，尚不能做出有关推荐。此外，用以评估维生素D和钙补充剂联合用于男性和绝经前女性骨折一级预防的利害证据也不充分。

然而，根据此前发布的报告，USPSTF的确曾推荐维生素D补充剂用于预防年龄≥65岁、跌倒风险高的社区老年人的跌倒，并建议对年龄≥65岁的女性进行骨质疏松筛查。对于较年轻的女性，如果其骨折风险与年龄≥65岁且无其他额外危险因素的白人女性相当或更高，也建议进行筛查。

新建议适用于无骨折史的非住院或社区无症状成人，但不适用于骨质疏松或维生素D缺乏者。

USPSTF承认，老年人群的骨折风险很高，近半数50岁以上女性一生中经历骨质疏松相关的骨折。但该工作组指出，妇女健康行动(WHI)研究证实，服用维生素D和钙补充剂的受试者肾结石风险增加也非常显著。在对服用补充剂女性的7年随访期间，每273例女性中就有1例被诊断为尿路结石。

为制定上述推荐意见，USPSTF对有关维生素D/钙补充剂的16项随机对照试验和1项Meta分析的证据进行了系统评价。

USPSTF成员报告无相关利益冲突。

随刊述评：谨慎值得称赞

纽约大学的Marion Nestle博士和康奈尔大学的Malden C. Nesheim博士评论指出，目前有关维生素D缺乏的最有效评估方法、大部分人群是否需要补充钙和维生素D以及补充多大剂量才能达到受益最大化和风险最小化等问题争议不断，必须围绕上述争议解读USPSTF的推荐意见。

评论者特别提到了美国医学研究所(IOM)和内分泌学会之间的“观点冲突”。基于“美国人维生素D和钙缺乏问题通常并不严重”的观点，IOM制定了平均成人每日推荐剂量，并对过量补充可能导致的不利影响表示担忧。与之相反，内分泌学会认为维生素D是一种激素，补充维生素D应被视为一种激素替代疗法，而维生素D缺乏常见于各年龄段人群，于是在2011年从临床内分泌学的角度制定了摄入推荐剂量。

评论者认为，USPSTF的建议可视为澄清这一问题的尝试。其建议基于硬性终点指标——骨折，而非25-羟基维生素D水平，这一做法值得称道，因为后者充其量是一种评估维生素D是否足够的间接指标。USPSTF采用了与IOM相同的谨慎原则，在缺乏强有力受益证据的情况下，服用补充剂所冒的风险不值得，无论其大小。

他们还指出，USPSTF计划发布有关维生素D作用的进一步建议，并力促工作组牢记制定单项建议的重要性，单项建议应考虑到所有的潜在利弊，避免多项推荐引起的困惑。

他们最后总结认为，在进一步研究结果出来之前，USPSTF谨慎的循证建议将会鼓励医生在向健康人群提供钙和维生素D补充剂咨询时，应三思而后行。

Nestle博士和Nesheim博士均声称没有与上述评论相关的利益冲突。

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By: SHARON WORCESTER

The U.S. Preventive Services Task Force has recommended against vitamin D and calcium supplementation in healthy postmenopausal women, citing research showing that such supplementation increases the risk of kidney stones and does not protect against fractures in this population.

Specifically, the USPSTF recommended – with moderate certainty – against supplementation with doses of vitamin D at 400 IU or less, and calcium at 1,000 IU or less in noninstitutionalized postmenopausal women. The evidence with respect to higher doses is insufficient for making a recommendation, Dr. Virginia A. Moyer reported on behalf of the USPSTF.

The evidence is also insufficient to assess the balance of the benefits and harms of combined vitamin D and calcium supplementation for the primary prevention of fractures in men and in premenopausal women, according to the recommendation statement, which was published online in the Feb. 25 issue of Annals of Internal Medicine.

Based on previously released recommendation statements, however, the USPSTF does recommend vitamin D supplementation for the prevention of falls in community-dwelling adults aged 65 years or older who are at increased risk for falls, and recommends that women aged 65 years and older be screened for osteoporosis.

Younger women with a fracture risk that is equal to or greater than that of a 65-year-old white woman with no additional risk factors should also be screened.

The new recommendations apply to noninstitutionalized or community-dwelling asymptomatic adults without a history of fractures; they do not apply to persons with osteoporosis or vitamin D deficiency.

The USPSTF acknowledged that the health burden of fractures is substantial in the older population, with nearly half of all women over age 50 years experiencing an osteoporosis-related fracture during their lifetime, but the task force noted that the increased risk of renal stones demonstrated in participants in the Women’s Health Initiative study who were taking supplemental vitamin D and calcium was also substantial.

"One woman was diagnosed with a urinary tract stone for every 273 women who received supplementation over a 7-year follow-up period," according to the recommendation statement.

In developing the recommendations, the USPSTF commissioned two systematic reviews of the evidence from 16 available randomized controlled trials and an updated meta-analysis of vitamin D supplementation with or without calcium supplementation.

The members of the USPSTF said they had no relevant financial disclosures.

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Cautious Approach Praised

The USPSTF’s recommendation "must be interpreted in the light of ongoing disputes about the most effective method for assessing vitamin D deficiency, whether calcium and vitamin D supplements are needed by a large portion of the population, and what level of supplementation might best maximize benefits and minimize risks," according to, Ph.D.

In particular, they cited the "conflicting perspectives" of the Institute of Medicine (IOM) and the Endocrine Society. Having determined that vitamin D and calcium deficiencies are generally not a serious problem in the United States, the IOM established average adult daily requirements for both, and has expressed concern about the possibility of adverse consequences from oversupplementation. Conversely, because vitamin D is a hormone, and supplementation must be considered a form of hormone replacement therapy, the Endocrine Society in 2011 made intake recommendations from a clinical endocrinology perspective based on the premise that vitamin D deficiencies are common among all age groups.

"The USPSTF’s recommendations can be understood as an attempt to clarify the present situation with respect to one specific outcome of supplementation. In doing so, its recommendations have a substantial advantage. They depend on hard endpoints – fractures – rather than on blood levels of 25-hydroxyvitamin D, at best an indirect measure of vitamin D adequacy. The USPSTF uses the same precautionary approach as did the IOM. In the absence of compelling evidence for benefit, taking supplements is not worth any risk, however small," they wrote.

Dr. Nestle and Dr. Nesheim noted that the USPSTF plans to publish further recommendations on the roles of vitamin D, and they urged the task force to "keep in mind the value of making a single recommendation ... that will encompass all potential benefits and risks" to avoid the confusion of multiple recommendations.

"While we wait for the results of further research, the USPSTF’s cautious, evidence-based advice should encourage clinicians to think carefully before advising calcium and vitamin D supplementation for healthy individuals," they concluded.

Dr. Nestle of New York University and Dr. Nesheim of Cornell University, Ithaca, N.Y., wrote their comments in an editorial responding to the USPSTF’s recommendations (Ann. Intern. Med. 2013). Dr. Nestle disclosed some speakers fees and royalties from published books unrelated to this editorial and Dr. Nesheim disclosed royalties from a book unrelated to this editorial.