Background: Elevated blood pressure (hypertension) affects about one billion people worldwide. It is important as it is a major risk factor for stroke and myocardial infarction. However, it remains a challenge for the medical profession as many people with hypertension have blood pressure (BP) that is not well controlled. According to Traditional Chinese Medicine theory, acupuncture has the potential to lower BP.
Objectives: To assess the effectiveness and safety of acupuncture for lowering blood pressure in adults with primary hypertension.
Search methods: We searched the Hypertension Group Specialised Register (February 2017); the Cochrane Central Register of Controlled Trials (CENTRAL) 2017, Issue 2; MEDLINE (February 2017); Embase (February 2017), China National Knowledge Infrastructure (CNKI) (January 2015), VIP Database (January 2015), the World Health Organisation Clinical Trials Registry Platform (February 2017)and ClinicalTrials.gov (February 2017). There were no language restrictions.
Selection criteria: We included all randomized controlled trials (RCTs) that compared the clinical effects of an acupuncture intervention (acupuncture used alone or add-on) with no treatment, a sham acupuncture or an antihypertensive drug in adults with primary hypertension.
Data collection and analysis: Two review authors independently selected studies according to inclusion and exclusion criteria. They extracted data and assessed the risk of bias of each trial, and telephoned or emailed the authors of the studies to ask for missing information. A third review author resolved disagreements. Outcomes included change in systolic blood pressure (SBP), change in diastolic blood pressure (DBP), withdrawal due to adverse effects, and any adverse events. We calculated pooled mean differences (MD) with 95% confidence intervals (CI) for continuous outcomes using a fixed-effect or random-effects model where appropriate.
Main results: Twenty-two RCTs (1744 people) met our inclusion criteria. The RCTs were of variable methodological quality (most at high risk of bias because of lack of blinding). There was no evidence for a sustained BP lowering effect of acupuncture; only one trial investigated a sustained effect and found no BP lowering effect at three and six months after acupuncture. Four sham acupuncture controlled trials provided very low quality evidence that acupuncture had a short-term (one to 24 hours) effect on SBP (change) -3.4 mmHg (-6.0 to -0.9) and DBP -1.9 mmHg (95% CI -3.6 to -0.3). Pooled analysis of eight trials comparing acupuncture with angiotensin-converting enzyme inhibitors and seven trials comparing acupuncture to calcium antagonists suggested that acupuncture lowered short-term BP better than the antihypertensive drugs. However, because of the very high risk of bias in these trials, we think that this is most likely a reflection of bias and not a true effect. As a result, we did not report these results in the 'Summary of findings' table. Safety of acupuncture could not be assessed as only eight trials reported adverse events.
Authors' conclusions: At present, there is no evidence for the sustained BP lowering effect of acupuncture that is required for the management of chronically elevated BP. The short-term effects of acupuncture are uncertain due to the very low quality of evidence. The larger effect shown in non-sham acupuncture controlled trials most likely reflects bias and is not a true effect. Future RCTs must use sham acupuncture controls and assess whether there is a BP lowering effect of acupuncture that lasts at least seven days.