Birkett N J
Department of Epidemiology and Community Medicine, University of Ottawa, Ontario, Canada.
Am J Epidemiol. 1998 Aug 1;148(3):223-8; discussion 232-3. doi: 10.1093/oxfordjournals.aje.a009627.
The role of dietary calcium in the etiology of hypertension is controversial. In 1995, Cappuccio et al. (American Journal of Epidemiology,1995;142:935-45) examined this issue in a meta-analysis of observational studies published between 1983 and 1993. The author of the present paper reviewed the original studies underlying this meta-analysis and discovered that data from one study had been inappropriately extracted and converted, leading to an understatement of the calcium-blood pressure relation by a factor of about 30. This review also raised questions about the extraction and conversion of data from several other studies and about the statistical methods used. The author repeated the meta-analyses and discovered an unadjusted regression slope between dietary calcium and systolic blood pressure of -0.34 mmHg/100 mg per day (95% confidence interval (CI) -0.46 to -0.22) for men, -0.15 mmHg/100 mg per day (95% CI -0.19 to -0.11) for women, and -0.39 mmHg/100 mg per day (95% CI -0.47 to -0.31) for men and women. For diastolic blood pressure, the pooled regression slope for men was -0.22 mmHg/100 mg per day (95% CI -0.32 to -0.13), while for women it was -0.051 mmHg/100 mg per day (95% CI -0.090 to -0.012); for men and women it was -0.35 mmHg/100 mg per day (95% CI -0.67 to -0.02). These slopes are still modest but are larger than those reported in the original analysis. However, since all of these analyses were based on zero-order correlations or regressions, extreme caution must be exercised in interpreting the results.
膳食钙在高血压病因学中的作用存在争议。1995年，卡普乔等人（《美国流行病学杂志》，1995年；142：935 - 45）在对1983年至1993年间发表的观察性研究进行的荟萃分析中研究了这个问题。本文作者回顾了该荟萃分析所依据的原始研究，发现一项研究的数据被不恰当地提取和转换，导致钙与血压关系的低估约30倍。这项回顾还对其他几项研究的数据提取和转换以及所使用的统计方法提出了疑问。作者重复了荟萃分析，发现男性膳食钙与收缩压之间未调整的回归斜率为-0.34 mmHg/每天100毫克（95%置信区间（CI）-0.46至-0.22），女性为-0.15 mmHg/每天100毫克（95%CI -0.19至-0.11），男性和女性合计为-0.39 mmHg/每天100毫克（95%CI -0.47至-0.31）。对于舒张压，男性的合并回归斜率为-0.22 mmHg/每天100毫克（95%CI -0.32至-0.13），而女性为-0.051 mmHg/每天100毫克（95%CI -0.090至-0.012）；男性和女性合计为-0.35 mmHg/每天100毫克（95%CI -0.67至-0.02）。这些斜率仍然较小，但比原始分析中报告的斜率要大。然而，由于所有这些分析都是基于零阶相关性或回归，在解释结果时必须极其谨慎。
