补钙或维生素Ｄ无法预防骨折？
在世界各地，骨质疏松相关骨折的社会和经济负担沉重，促使预防此类骨折成为一项重要的公共卫生目标。对于补充钙、维生素D、钙＋维生素D与老年骨折风险之间相关性，既往研究结论存在分歧。2013年，奥克兰大学通过PubMed检索出24篇关于维生素D±钙与骨折相关性的荟萃分析，并对期刊排名最高的7篇荟萃分析进行了评估，结果发现这些荟萃分析总共纳入了25项研究，其中3篇荟萃分析遗漏了3～8项研究、2篇荟萃分析纳入了显然不符合要求的研究。2014年，奥克兰大学又对2009年1月1日～2014年12月31日发表的78篇临床指南关于骨骼健康评定、治疗、监测的推荐意见进行了分析，发现其中63～71%推荐了钙±维生素D。2016年发表的澳大利亚养老护理机构治疗骨质疏松、预防骨折的共识推荐意见认为，生活在养老院和护理院等机构的老年人与社区老年居民相比，骨折风险较高。那么，补充钙、维生素D、钙＋维生素D与社区老年居民骨折风险较低，是否存在相关性？
2017年12月26日，《美国医学会杂志》网站首页头条正式发表中国天津市天津医院和河北省沧州中西医结合医院四位骨科博士的研究报告，对于补充钙、维生素D、钙＋维生素D与社区老年居民骨折风险较低是否存在相关性进行了系统回顾与荟萃分析。简而言之，即对随机对照研究二次分析的三次分析。
作者使用关键词（钙、维生素D、骨折）对PubMed、考科蓝图书馆、EMBASE数据库从建立之日期起截至2016年12月24日发表的系统回顾或荟萃分析进行系统检索，筛选系统回顾或荟萃分析纳入的主要随机临床研究，并且对2012年7月16日～2017年7月16日发表的最新随机研究进行附加检索。研究筛选标准：对50岁以上社区居民补充钙、维生素D、钙＋维生素D与安慰剂或不治疗的骨折风险进行比较的随机临床研究。由两位回顾者独立进行数据提取并评定研究质量。使用随机效应模型，进行荟萃分析，计算风险比、绝对风险差、95%置信区间。主要结局衡量指标为髋部骨折，次要结衡量指标局为非椎骨骨折、椎骨骨折、全部骨折。
最后，作者共筛选出21篇已经发表的系统回顾与荟萃分析，其中33项随机研究共51145例参与者符合要求，结果发现与安慰剂或不治疗相比：
补充钙与髋部骨折无显著相关性（P=0.07）
风险比：1.53（95%：0.97～2.42）
风险差：0.01（95%：0.99～1.47）
补充维生素D与髋部骨折风险无显著相关性（P=0.06）
风险比：1.21（95%：0.00～0.01）
风险差：0.00（95%：-0.00～0.01）
补充钙＋维生素D与髋部骨折风险无显著相关性（P=0.50）
风险比：1.09（95%：0.85～1.39）
风险差：0.00（95%：-0.00～0.00）
补充钙、维生素D、钙＋维生素D与非椎骨、椎骨、全部骨折风险均无显著相关性。
根据亚组分析，无论补充钙或维生素D的剂量、性别、骨折史、饮食钙摄入量、血清25-羟维生素D基础浓度如何，上述结果基本一致。
因此，根据随机临床研究的荟萃分析，补充钙、维生素D、钙＋维生素D与安慰剂或不治疗相比，与社区老年居民骨折风险较低的关系不大。上述结果不支持社区老年居民为了预防骨折而盲目补充这些营养素。
不过，作者承认，由于该荟萃分析其中某些研究未检测所有参与者的血清维生素D基础浓度，故若所有个体均经检测，某些亚组分析结果可能有所不同。此外，某些入选随机对照研究质量不高，例如使用了不明确的随机分组隐匿，而将研究划分为质量高的方法可能相对宽松，其他作者可能选择不同的研究质量定义。
对此，天津医院官方网站、微博和微信公众号在第一时间进行了详细报道：国际顶级医学期刊JAMA（IF=44.405）发表天津医院赵嘉国和曾宪铁团队论文，彻底颠覆骨质疏松防治理念。
2017年12月28日，国家卫生和计划生育委员会《健康报》头版也进行了报道，并被新华网等网络媒体转载。
更有国内医学网络媒体直接将一首《凉凉》送给了钙尔奇D……
JAMA. 2017 Dec 26;318(24):2466-2482.
Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis.
Jia-Guo Zhao; Xian-Tie Zeng; Jia Wang; Lin Liu.
Tianjin Hospital, Tianjin, China; Hebei Province Cangzhou Hospital of Integrated Traditional and Western Medicine, Cangzhou, China.
This meta-analysis summarizes the effects of calcium, vitamin D, or combined calcium and vitamin D supplements on fracture incidence among community-dwelling older adults.
QUESTION: Is supplementation with calcium, vitamin D, or combined calcium and vitamin D associated with a lower fracture incidence in community-dwelling older adults?
FINDINGS: In this meta-analysis of 33 randomized clinical trials that included 51145 participants, the use of supplements that included calcium, vitamin D, or both was not associated with a significant difference in the risk of hip fractures compared with placebo or no treatment (risk ratio, 1.53, 1.21, and 1.09, respectively).
MEANING: These findings do not support the routine use of these supplements in community-dwelling older adults.
IMPORTANCE: The increased social and economic burdens for osteoporosis-related fractures worldwide make the prevention of such injuries a major public health goal. Previous studies have reached mixed conclusions regarding the association between calcium, vitamin D, or combined calcium and vitamin D supplements and fracture incidence in older adults.
OBJECTIVE: To investigate whether calcium, vitamin D, or combined calcium and vitamin D supplements are associated with a lower fracture incidence in community-dwelling older adults.
DATA SOURCES: The PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to December 24, 2016, using the keywords calcium, vitamin D, and fracture to identify systematic reviews or meta-analyses. The primary randomized clinical trials included in systematic reviews or meta-analyses were identified, and an additional search for recently published randomized trials was performed from July 16, 2012, to July 16, 2017.
STUDY SELECTION: Randomized clinical trials comparing calcium, vitamin D, or combined calcium and vitamin D supplements with a placebo or no treatment for fracture incidence in community-dwelling adults older than 50 years.
DATA EXTRACTION AND SYNTHESIS: Two independent reviewers performed the data extraction and assessed study quality. A meta-analysis was performed to calculate risk ratios (RRs), absolute risk differences (ARDs), and 95% CIs using random-effects models.
MAIN OUTCOMES AND MEASURES: Hip fracture was defined as the primary outcome. Secondary outcomes were nonvertebral fracture, vertebral fracture, and total fracture.
RESULTS: A total of 33 randomized trials involving 51145 participants fulfilled the inclusion criteria. There was no significant association of calcium or vitamin D with risk of hip fracture compared with placebo or no treatment (calcium: RR, 1.53 [95% CI, 0.97 to 2.42]; ARD, 0.01 [95% CI, 0.00 to 0.01]; vitamin D: RR, 1.21 [95% CI, 0.99 to 1.47]; ARD, 0.00 [95% CI, -0.00 to 0.01]. There was no significant association of combined calcium and vitamin D with hip fracture compared with placebo or no treatment (RR, 1.09 [95% CI, 0.85 to 1.39]; ARD, 0.00 [95% CI, -0.00 to 0.00]). No significant associations were found between calcium, vitamin D, or combined calcium and vitamin D supplements and the incidence of nonvertebral, vertebral, or total fractures. Subgroup analyses showed that these results were generally consistent regardless of the calcium or vitamin D dose, sex, fracture history, dietary calcium intake, and baseline serum 25-hydroxyvitamin D concentration.
CONCLUSIONS AND RELEVANCE: In this meta-analysis of randomized clinical trials, the use of supplements that included calcium, vitamin D, or both compared with placebo or no treatment was not associated with a lower risk of fractures among community-dwelling older adults. These findings do not support the routine use of these supplements in community-dwelling older people.
DOI: 10.1001/jama.2017.19344