Dickinson H O, Nicolson D J, Campbell F, Beyer F R, Mason J
Cochrane Database Syst Rev. 2006 Jul 19(3):CD004641. doi: 10.1002/14651858.CD004641.pub2.
Epidemiological evidence on the effects of potassium on blood pressure is inconsistent.
To evaluate the effects of potassium supplementation on health outcomes and blood pressure in people with elevated blood pressure.
We searched the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, ISI Proceedings, ClinicalTrials.gov, Current Controlled Trials, CAB abstracts, and reference lists of systematic reviews, meta-analyses and randomised controlled trials (RCTs) included in the review.
Inclusion criteria were: 1) RCTs of a parallel or crossover design comparing oral potassium supplements with placebo, no treatment, or usual care; 2) treatment and follow-up >=8 weeks; 3) participants over 18 years, with raised systolic blood pressure (SBP) >=140 mmHg or diastolic blood pressure (DBP) >=85 mmHg); 4) SBP and DBP reported at end of follow-up. We excluded trials where: participants were pregnant; received antihypertensive medication which changed during the study; or potassium supplementation was combined with other interventions.
Two reviewers independently extracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Random effects meta-analyses and sensitivity analyses were conducted.
Six RCT's (n=483), with eight to 16 weeks follow-up, met our inclusion criteria. Meta-analysis of five trials (n=425) with adequate data indicated that potassium supplementation compared to control resulted in a large but statistically non-significant reductions in SBP (mean difference: -11.2, 95% CI: -25.2 to 2.7) and DBP (mean difference: -5.0, 95% CI: -12.5 to 2.4). The substantial heterogeneity between trials was not explained by potassium dose, quality of trials or baseline blood pressure. Excluding one trial in an African population with very high baseline blood pressure resulted in smaller overall reductions in blood pressure (SBP mean difference: -3.9, 95% CI: -8.6 to 0.8; DBP mean difference: -1.5, 95% CI: -6.2 to 3.1). Further sensitivity analysis restricted to two high quality trials (n=138) also found non-significant reductions in blood pressure (SBP mean difference: -7.1, 95% CI: -19.9 to 5.7; DBP mean difference: -5.5, 95% CI: -14.5 to 3.5).
AUTHORS' CONCLUSIONS: This systematic review found no statistically significant effect of potassium supplementation on blood pressure. Because of the small number of participants in the two high quality trials, the short duration of follow-up, and the unexplained heterogeneity between trials, the evidence about the effect of potassium supplementation on blood pressure is not conclusive. Further high quality RCTs of longer duration are required to clarify whether potassium supplementation can reduce blood pressure and improve health outcomes.
关于钾对血压影响的流行病学证据并不一致。
评估补充钾对血压升高人群健康结局和血压的影响。
我们检索了Cochrane图书馆、MEDLINE、EMBASE、科学引文索引、ISI会议录、ClinicalTrials.gov、当前对照试验、CAB文摘以及纳入本综述的系统评价、荟萃分析和随机对照试验（RCT）的参考文献列表。
入选标准为：1）平行或交叉设计的RCT，比较口服钾补充剂与安慰剂、不治疗或常规护理；2）治疗和随访≥8周；3）年龄超过18岁，收缩压（SBP）≥140 mmHg或舒张压（DBP）≥85 mmHg；4）随访结束时报告SBP和DBP。我们排除了以下试验：参与者为孕妇；接受在研究期间发生变化的抗高血压药物治疗；或钾补充剂与其他干预措施联合使用。
两名评价员独立提取数据并评估试验质量。分歧通过讨论或第三位评价员解决。进行了随机效应荟萃分析和敏感性分析。
六项RCT（n = 483）满足我们的纳入标准，随访时间为8至16周。对五项数据充分的试验（n = 425）进行的荟萃分析表明，与对照组相比，补充钾导致SBP有较大但无统计学意义的降低（平均差值：-11.2，95%置信区间：-25.2至2.7）和DBP（平均差值：-5.0，95%置信区间：-12.5至2.4）。试验之间的显著异质性无法用钾剂量、试验质量或基线血压来解释。排除一项非洲人群基线血压非常高的试验后，血压总体降低幅度较小（SBP平均差值：-3.9，95%置信区间：-8.6至0.8；DBP平均差值：-1.5，95%置信区间：-6.2至3.1）。进一步的敏感性分析仅限于两项高质量试验（n = 138），也发现血压有非显著降低（SBP平均差值：-7.1，95%置信区间：-19.9至5.7；DBP平均差值：-5.5，95%置信区间：-14.5至3.5）。
本系统评价发现补充钾对血压无统计学显著影响。由于两项高质量试验的参与者数量较少、随访时间较短以及试验之间无法解释的异质性，关于补充钾对血压影响的证据并不确凿。需要进一步开展持续时间更长的高质量RCT，以明确补充钾是否能降低血压并改善健康结局。
