Systematic reviews form the basis of evidence-based practice (Macnee & McCabe, 2008). This is the “conscientious and judicious” use of current, quality research to guide practice (Titler et al., 2019: p.3). Evidence-based practice is important: research consistently shows that it decreases variability in practice and, subsequently, improves patient outcomes (Emparanza et al., 2015; Black et al., 2015). Therefore, the Nursing and Midwifery Council’s (2018: p.9) Code requires all nurses in the UK to “always practice in line with the best available evidence”.
Systematic reviews differ from other types of literature reviews because the methods used to retrieve, critically appraise, synthesise and summarise the studies is detailed and repeatable (Webb & Roe, 2007). Systematic reviews aim to gather all the available primary research on the topic, and therefore require methods which are carefully designed and implemented (Clarke, 2011). The methods used for this review are presented and justified in the following sections.
2.1 Research Question
Grove et al. (2013) recommend that all literature reviews are based on a well-developed research question, to focus the searches and the evidence retrieved. There are a number of different frameworks which can be used to develop clear, answerable research questions (Grove et al., 2013). The question for this review was developed using the population-intervention-comparator-outcome (PICO) framework. This is the most common framework for developing research questions for reviews involving quantitative studies (Houser, 2018).
The PICO framework completed for this review is shown in Appendix 1. The population (P) was adults with confirmed hypertension, the intervention (I) was needle acupuncture, the comparator (C) was sham acupuncture, and the outcome (O) was change in systolic and/or diastolic blood pressure. This gave the research question: ‘In patients with hypertension, is acupuncture, in comparison to sham acupuncture, effective at reducing systolic and/or diastolic blood pressure?’
2.2 Electronic Databases
Electronic databases are the “major sources of information” for literature reviews (Coughlan & Cronin, 2017: p.56), and so the searches for this review focused on these databases. Five databases were searched: the British Nursing Index (BNI), the Cumulative Index of Nursing and Allied Health Literature (CINAHL), Excerpta Medica Online (EMBASE), Medical Literature Online (MEDLINE) and the Web of Science. These are identified as the key electronic databases to access studies related to nursing and broader health topics (Moule et al., 2017).
In addition to electronic database searches, manual searches were also completed. This involved ‘back-chaining’, or searching the reference lists of selected studies to identify other potentially-relevant studies (Tappen, 2011). Back-chaining improves the comprehensiveness of the searches undertaken, and increase the number of studies retrieved (Holland & Rees, 2010).
2.3 Search Terms
As recommended by Aveyard (2014), the terms used to search the databases were developed from the research question. The key words in the research question – including hypertension and acupuncture – and their synonyms were used. A full list of terms is provided in Appendix 2.
Where relevant, the search terms were truncated with an asterisk; this ensured the searches captured words with variable endings and spellings (Courtney & McCutcheon, 2010). For example: searching with the term hypertens* retrieved studies containing hypertension and hypertensive. Groups of keywords were also placed in parentheses; this ensured the searches captured entire terms rather than each word separately (Dieterle & Hooper-Lane, 2014). For example: searching with the term “blood pressure” retri
