BMJ前瞻性队列研究：增加钙摄入未能降低骨折风险
2011-05-30 23:17:14   来源：   作者：  评论：0 点击：

May 25, 2011 — Gradual increases in dietary calcium intake above the first quintile in a large female cohort are not associated with further reductions in fracture risk or osteoporosis, according to the results of a prospective longitudinal cohort studyreported in the May 24 issue of the BMJ.
根据一份发表在5月24日BMJ上的以大量女性作为研究样本的前瞻性队列研究，在队列中摄入钙最多的25%人里逐渐增加每日饮食中钙的摄入，并不能降低未来骨折或患骨质疏松的风险。

"It is problematic to make recommendations regarding calcium intake based on the results from clinical trials and previous cohort studies," write Eva Warensj?, from Uppsala University in Uppsala, Sweden, and colleagues. "Meta-analyses of randomised trials found that supplemental calcium gave modest or no reduction in risk of fracture. Both the habitual dietary intake of calcium and vitamin D status may affect the outcome and are rarely accounted for in the design of calcium supplementation trials."
瑞典乌普萨拉大学的Eva Warensj? 教授在文章中写道：“根据临床试验或先前队列研究的结果作出钙摄入的建议是有问题的。随机临床试验的Meta分析显示，辅助性的钙补充不能或者只能轻度降低骨折发生的风险。日常饮食钙摄入及维生素D摄入状况可以影响骨质状态，但基本不能作为钙补充试验方案设计的标准。”

The goal of the study was to evaluate associations between long-term dietary calcium intake and the risk for any type of fractures, hip fractures, and osteoporosis. The study cohort consisted of 5022 women who participated in a subcohort of the Swedish Mammography Cohort of 61,433 women in Sweden who were born between 1914 and 1948. This population-based cohort was established in 1987, and participants were followed up for 19 years for primary outcomes of incident fractures of any type and hip fractures, which were identified from registry data.
研究的目的是评价长期饮食钙摄入与普通骨折、髋部骨折及骨质疏松发生风险的关系。研究队列包括了5022名妇女，这些受试者属于瑞典乳腺X 线摄影队列计划中的61433名出生在1914到1948年的妇女的子队列。这个以人口为基础的队列在1987年建立。受试者接受了长达19年的随访。主要随访内容是外伤性（机会性？）骨折及髋部骨折的初步预后。这些内容根据经过注册登记的数据确认。

A secondary outcome in the subcohort was osteoporosis diagnosed by dual energy x-ray absorptiometry. Repeated food frequency questionnaires allowed determination of dietary consumption.
子队列的第二个研究结果是由双能力X 线吸光分析诊断的骨质疏松情况。食物摄入频率问卷反复调查受试者日常饮食钙摄入。

Of 14,738 women (24%) who had a first fracture of any type during follow-up, 3871 (6%) had a first hip fracture. Osteoporosis was diagnosed in 1012 (20%) of the subcohort. For dietary calcium, the risk patterns were nonlinear. In the lowest quintile of calcium intake, the crude rate of a first fracture of any type was 17.2/1000 person-years at risk vs 14.0/1000 person-years at risk in the third quintile, yielding a multivariable adjusted hazard ratio (HR) of 1.18 (95% confidence interval [CI], 1.12 - 1.25). For a first hip fracture, the HR was 1.29 (95% CI, 1.17 - 1.43), and the odds ratio for osteoporosis was 1.47 (95% CI, 1.09 - 2.00).
在随访中发生第一次骨折的14738名妇女中（24%），有3871（6%）名发生髋部骨折。1012名（20%）被诊断为骨质疏松。而日常钙摄入与骨折/骨质疏松风险的关系呈非线性关系。在钙摄入最低的25%的人群中，第一次骨折发生的风险粗概率为17.2/1000人年，而在钙摄入量的第三个梯队的25%的人群中，此概率为14.0/1000人年。经过多变量校正，相对危险度为1.18，95%置信区间为1.12 - 1.25。第一次髋部骨折的相对危险度为1.29（95%置信区间为1.17 - 1.43），患骨质疏松的优势比为1.47（95%置信区间为1.09 - 2.00）。

The fracture rate in the first calcium quintile was more pronounced with a low vitamin D intake. Although the highest quintile of calcium intake did not further lower the risk for fractures of any type, or the risk for osteoporosis, it was associated with a higher rate of hip fracture (HR, 1.19; 95% CI, 1.06 - 1.32).
第一梯队前25%的骨折发生率比低量摄入维生素D的妇女更高。尽管钙摄入最高的梯队里并没有显示骨折发生率或骨质疏松患病风险的下降，但却与髋部骨折发生率上升相关（相对危险度为1.19，95%置信区间为1.06 - 1.32）。

"Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis," the study authors write.
研究者写道：“第一梯队中逐渐增加日常饮食钙摄入并未与骨折或骨质疏松患病风险下降相关。”

Limitations of this study include possible residual confounding; limitations inherent in dietary assessment methods; observational design, precluding conclusions regarding causality; and lack of generalizability to other people of different ethnic origins or to men.
此次研究的局限性包括潜在的残差混杂、日常饮食评估方法固有的局限、未能推导出因果关系的观察设计、未能把结论推广到其他种族或男性。

"Dietary calcium intakes below approximately 700 mg per day in women were associated with an increased risk of hip fracture, any fracture, and of osteoporosis," the study authors conclude. "The highest reported calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture."
研究者最后总结道：“女性日常饮食中钙摄入低于每日700毫克与髋部骨折、普通骨折及骨质疏松风险上升相关。而钙摄入最高的人群并未显示进一步下降普通骨折和骨质疏松的风险，却与髋部骨折风险上升相关。”