The results indicate that CAM use is common in cardiac patients but the prevalence of CAM use varies significantly (4%-61%). The large range found is consistent with other reviews in the CAM literature [2
]. The findings have strong implications for both clinical practice and research in this field. The lack of specific and consistent definitions of CAM in the reviewed studies contribute to the variability observed and has made generalisations difficult. A standard and complete definition of CAM use would facilitate meta-analysis in future studies [43
The reasons for CAM use vary remarkably between different cohorts although six studies did find that patients used CAM specifically for the management of their CVDs. Although our review has found inconsistent results with regard to the association between CAM use and compliance, some evidence exists to suggest that CAM use may affect the compliance of prescription medicines [14
]. A patients’ belief that their CAM usage help manage their CVD may give them a false sense of security that may lead to a reduction of their concurrently medicines.
We found across the studies that patients with CVD are likely to be using more than one CAM product simultaneously [9
]. There appeared to be little awareness that there may be interactions with their prescription medication, having potential additive or negative effects on the therapeutic levels of their medication or a harmful adverse effect [28
]. Supplemental potassium was taken by 20% of patients in one study [29
], which can result in adverse outcomes when used together with commonly prescribed medications such as angiotensin converting enzyme inhibitors, aldosterone receptor antagonists, or angiotensin receptor blockers. The potential effects and implications of herb-drug interaction with CVD medications have been discussed in detail elsewhere [44
It is of great concern that a large proportion of medical practitioners (35 ‐ 92%) were unaware of the CAM use by their patients [12
]. Although patients may be reluctant to disclose CAM use because they fear disapproval, doctors also do not appear to be asking their patients about CAM use [31
The results of our review are restricted in several aspects. For example, the quality of the reviewed studies was highly variable. Data collection in most of the studies was retrospective. This led to high variability in the resulting prevalence rates and may have introduced significant recall bias. Many studies also lacked the use of a validated survey, a representative sample, and rarely did the study authors address potential biases arising from their methods. Many of the studies failed to report the frequency and duration of CAM use. Several studies made use of clinical samples, but few provided objective data on the health status of the patients. The results presented here should therefore be treated with caution. We were only able to include studies published in the English language and therefore the findings have limited generalisability outside of English-speaking regions. However we note that it is within countries such as Australia and the United States where use and concerns about CAM are growing the fastest. Therefore the current study provides much needed information on these areas.