3.2.4 Sustainability of the Effects of Acupuncture on Hypertension
Only two of the trials selected for inclusion in this review included a post-intervention follow-up period of a sufficient length to determine if the effects of acupuncture on hypertension are sustainable (Macklin et al., 2006: 12-month follow-up; Flachskampf et al., 2007: 6-month follow-up). In Macklin et al.’s (2006) trial, the effects of the acupuncture on participants’ blood pressure began to diminish from 10 weeks post-intervention. In Flachskampf et al.’s (2007) study, participants’ mean blood pressure approximated mean baseline blood pressure from 12 weeks post-intervention. This suggests the effects of acupuncture on hypertension are not sustainable.
3.2.5 Negative Effects of Acupuncture for the Management of Hypertension
Two-thirds of the trials (n=4, 66.7%) identified adverse events associated with acupuncture. These included “hypertensive urgencies” (Macklin et al., 2006: p.842), minor pain at the acupuncture site (Flachskampf et al., 2007; Kim et al., 2012), minor haematoma and/or bleeding at the acupuncture site (Kim et al., 2012; Zheng et al., 2018) and minor nausea during acupuncture (Zheng et al., 2018). In all four of these studies, adverse events occurred more frequently in the intervention group than in the control group. However, two of the trials calculated the significance of adverse events, and both concluded that the risk of an adverse event associated with acupuncture was no more significant than the risk of and adverse event associated with sham acupuncture (Macklin et al., 2006: p>0.68; Zheng et al., 2008: p=0.147).
3.3 Critical Review
The critical appraisals of the randomised controlled trials selected for inclusion in this review, presented in Appendix 8, show that each trial is of acceptable methodological quality. When the trials are pooled and synthesised for the purposes of a systematic review, however, problems arise. There are also complexities associated with aspects of the randomised controlled trial methodology. These limitations are critically examined in the following sections of the review.
3.3.1 Use of Acupuncture in the Trials
The most significant limitation of the trials selected for inclusion in this review is that no two studies test precisely the same acupuncture protocol. As shown previously, there were differences among the trials in terms of the type of acupuncture used (Chines versus Korean). Subsequently, there were differences in acupoints accessed, the duration of the intervention, the number of acupuncture sessions (overall and per week), and the duration of each session.
As explained by Webb and Roe (2007: p.47), when there is major disparity between the studies included in a review, this can result in the “comparison of apples and oranges” – a meaningless activity. However, due to the paucity of literature on the topic of acupuncture for hypertension, disparities in acupuncture protocols are an unavoidable limitation, and this was also identified in the Cochrane systematic review on the topic (Yang et al., 2018). Disparities in the protocols used in the trials selected for inclusion in this review did, however, prevent a meta-analysis being undertaken, and so the review findings could only be presented in simpler narrative form.
Another problem associated with the use of acupunct
