Bucher H C, Cook R J, Guyatt G H, Lang J D, Cook D J, Hatala R, Hunt D L
Department of Clinical Epidemiology and Biostatistics, McMaster University Medical Center, Hamilton, Ontario, Canada.
JAMA. 1996 Apr 3;275(13):1016-22. doi: 10.1001/jama.1996.03530370054031.
To review the effect of supplemental calcium on blood pressure.
We searched MEDLINE and EMBASE for 1996 to May 1994. We contacted authors of eligible trials to ensure accuracy and completeness of data and to identify unpublished trials.
We included any study in which investigators randomized people to calcium supplementation or placebo and measured blood pressure for at least 2 weeks. Fifty-six articles met the inclusion criteria, and 33 were eligible for analysis, involving a total of 2412 patients.
Two pairs of independent reviewers abstracted data and assessed validity according to six quality criteria.
We calculated the differences in blood pressure change between the calcium supplementation group and the control group and pooled the estimates, with each trial weighted with the inverse of the variance using a random-effects model. Predictors of blood pressure reduction that we examined included method of supplementation, baseline blood pressure, and the methodological quality of the studies. The pooled analysis showed a reduction in systolic blood pressure of -1.27 mm Hg (95% confidence interval [CI], -2.25 to -0.29 mm Hg; P=.01) and in diastolic blood pressure of -0.24 mm Hg (95% CI, -0.92 to 0.44 mm Hg; P=.49). None of the possible mediators of blood pressure reduction explained differences in treatment effects.
Calcium supplementation may lead to a small reduction in systolic but not diastolic blood pressure. The results do not exclude a larger, important effect of calcium on blood pressure in subpopulations. In particular, further studies should address the hypothesis that inadequate calcium intake is associated with increased blood pressure that can be corrected with calcium supplementation.
综述补充钙对血压的影响。
我们检索了1994年5月至1996年的MEDLINE和EMBASE数据库。我们联系了符合条件的试验的作者，以确保数据的准确性和完整性，并识别未发表的试验。
我们纳入了任何一项研究，其中研究者将受试者随机分为补钙组或安慰剂组，并测量血压至少2周。56篇文章符合纳入标准，33篇符合分析条件，共涉及2412例患者。
两对独立的评审员提取数据，并根据六项质量标准评估有效性。
我们计算了补钙组和对照组之间血压变化的差异，并汇总估计值，使用随机效应模型对每个试验以方差的倒数进行加权。我们研究的血压降低的预测因素包括补充方法、基线血压和研究的方法学质量。汇总分析显示，收缩压降低了-1.27 mmHg（95%置信区间[CI]，-2.25至-0.29 mmHg；P = 0.01），舒张压降低了-0.24 mmHg（95%CI，-0.92至0.44 mmHg；P = 0.49）。血压降低的任何可能的介导因素均无法解释治疗效果的差异。
补钙可能导致收缩压小幅降低，但舒张压无明显变化。这些结果不排除钙对亚人群血压有更大、更重要的影响。特别是，进一步的研究应探讨钙摄入不足与血压升高相关，而补钙可纠正这一假设。
