Validity

According to Walsh (2001:15), validity refers to the issue of whether data collected is a true reflection of what is being studied. Until recently, validity has been categorised into three types: content, predictive and construct, each with its own sub-types. According to Burns and Grove (2009:380), validity is currently only categorised as

construct validity, which includes content and predictive validity as the sub-

types. Construct validity examines the fit between the conceptual and operational definitions of variables and determines whether the instrument actually measures the theoretical construct that it purports to measure (Burns and Grove, 2009:693).

Content validity assesses the extent to which the measuring instrument includes all the major elements relevant to the construct being measured. Content validity testing determines clarity and relevance of the content of the measuring instrument (Burns and Grove, 2009:382). The sources that have been used in constructing the measuring instrument need to be assessed. These sources can include literature, representatives of the relevant population and content experts. Content validity of the questionnaire in the study was ensured by using relevant literature sources in constructing the structured questionnaire. The questionnaire was discussed with various experts in the field of critical care, who included a clinical facilitator in critical care nursing, a lecturer in the field of critical care nursing, a professional nurse working in the critical care unit, the research promoter and the statistician, who specifically assessed the content of the questionnaire. The pilot study revealed that the content of the questionnaire was clear and understandable to the participants. The questionnaire was based on the results from the narrative literature review done

126

on the four identified nursing care practices as well as the core concepts of the study.

Predictive validity refers to an instrument where future performance or attitudes are proposed or predicted based on an instrument score (Burns and Grove, 2009: 715). Predictive validity was not used in this research study.

Readability of an instrument used in the study is another essential aspect to consider in measuring the reliability and validity of that instrument. Readability has never been formally identified as a component of content validity but Burns and Grove (2009:384) suggest that it should be considered, as incomprehensible content cannot be valid. Although there are various readability formulas available for test the readability of an instrument, these were not used in this study. The structured questionnaire was submitted to the various experts above who had assessed the layout, technical care, readability of the instrument and clarity of the questions asked. The participants did not report any uncertainties in completing the questionnaires during the pilot study, thus proving that the structured data collection instrument used for this research study was valid.

3.2.3 STEP TWO: SYSTEMATIC REVIEW

Step Two in Stage One of the research study comprised of a systematic review, which was done in order to explore and describe existing literature for the two identified nursing care practices related to the safety of the mechanically ventilated patient in a critical care unit. The two nursing care practices were identified following the data analysis from the structured questionnaires, indicating the nursing care practices that were done least according to best recommended practices. This section aims to discuss the design, method and measurements of ensuring quality in performing a systematic review.

3.2.3.1 Research design

A literature review that is performed systematically, as in the case of a systematic review, is a research methodology in its own right (Aveyard, 2010:19). This section

127

describes the differences between a systematic review and a narrative literature review.

3.2.3.1.1 Systematic review

The systematic review is a fundamental component of evidence-based practice. According to Egger, Smith and Altman (2001:5), a systematic review is defined as a review that has been prepared using a systematic approach to minimising biases and random errors which is documented in a materials and methods section. Systematic reviews are essential tools for health care workers, researchers, consumers and policy makers who want to keep up with the evidence that is accumulating in their fields. In performing a systematic review, the lack of adequate evidence in the field of interest might be demonstrated and areas where further research studies are needed are identified. Systematic reviews allow a more objective appraisal of the evidence than narrative literature reviews and may contribute to resolve uncertainties when original research, reviews and editorials disagree. Systematic reviews use rigorous methods to reduce bias and can provide reliable summaries of relevant research evidence (Craig and Smyth, 2007:186).

A systematic review allows for critical synthesis of research evidence, which involves analysis of all available and relevant evidence in a systematic, objective and robust manner. Systematic reviews use objective, explicit and transparent methods, which allow the reader to follow how conclusions were reached. In areas where no evidence exists, or where current evidence is inconclusive, systematic reviews may be helpful indicating where further primary research is required (Bruce and Mollison, 2004:13).

3.2.3.1.2 The purpose of a performing a systematic review

The body of knowledge on which healthcare is based is changing rapidly and so what is taught to nursing students might remain relevant for only a limited period of time. Keeping up to date with this changing knowledge can be very difficult. According to Evans (2001:52) it has been estimated that approximately 20 000-30 000 biomedical journals are published annually. As a result of this, the number of clinical trial reports available has become too large for clinicians to comprehend on

128

an on-going basis. Further, the quality of published research is highly variable. The use of inappropriate research methods, poor standards of statistical analysis or inadequate sample size often make research findings inconclusive or contradictory. This makes it difficult to know which studies should be used as the basis for clinical practice. As a result, systematic reviews have become an increasingly important means by which research results are collected, sorted, appraised and summarised. Systematic reviews help in overcoming the problems associated with large amounts of published research and variations in quality between studies. While there is a range of approaches to reviewing research literature, properly conducted systematic reviews are seen to be the most reliable (http://www.joannabriggs.edu.au).

3.2.3.1.3 Systematic review versus a narrative literature review

In contrast to the narrative review, which might simply reflect the findings of a few papers that support an author‟s particular point of view, a systematic review entails systematic and explicit methods to identify, appraise and synthesize relevant studies in a specific subject (Craig and Smyth, 2007:101). Narrative literature reviews are undertaken with no defined method or systematic approach. A narrative literature review might fail to identify, include or appraise all the available evidence or specify the process by which judgements, conclusions and recommendations are made. Narrative literature reviews do not routinely incorporate all relevant up-to date scientific data. Furthermore, narrative literature reviews only attempt to summarise a body of literature and draw conclusions about the topic in question. The body of literature is made up of the relevant studies and knowledge that address the subject area. It is selective in the material it uses, although the criteria for selecting specific sources are not always apparent to the reader (Aveyard, 2010:16).

According to Rolls and Elliot (2008:202), a systematic review is underpinned by a rigorous process of:

 Developing a well-focused clinical question;

 Conducting an exhaustive search for literature related to this question by developing a well-focused searching strategy;

129

 Reviewing published and unpublished literature in a systematic way to identify the quality of research undertaken to verify the reliability and validity of the study findings;

 Appraising the literature;

 Developing a synthesis of these evaluations.

Narrative literature reviews, on the other hand, have no focussed research question, no focussed searching strategy and no clear method of appraisal or synthesis of literature (Aveyard, 2010:19).

In this research study, both approaches to searching for literature were used. A narrative literature review was done to give the reader insight into mechanical ventilation and the core concepts of the study, as well as all the four identified nursing care practices. The data obtained from the narrative literature review was necessary in order to guide the construction of the questionnaire. Due to the scope of the study, it was decided to perform two systematic reviews. The selection for the two nursing care practices to be included in the systematic review was based on the data analysis from the structured questionnaires. The nursing care practices that obtained the lowest score, implying that they were done the least according to best practice recommendations, were included for selection into the systematic review .As far possible, it was aimed not to include literature that has been used in the narrative review in the systematic review of the two identified nursing care practices.

3.2.3.1.4 The rationale for performing systematic reviews in this research study

According to Craig and Smyth (2007:206), systematic reviews are an important element of evidence-based practice, and evidence-informed practice when considering different types of evidence in order to draw conclusions. As illustrated in Chapter 1 of this study, there is an increasing emphasis been placed on basing health care decisions on best available evidence, thereby reducing health care costs and improving the quality of patient care. Within a critical care unit, decision-making is crucial and should be based on sound, valid and reliable evidence. Furthermore, it is important that nursing care practices be aimed at providing safe, effective and

130

sufficient patient care. If the evidence is presented in a way which makes the application easier, then clinicians may be more likely to use it (Bazian, 2005:270). The systematic review provided summaries on the best available evidence and guided the development of evidence-informed clinical guidelines to distil the large body of knowledge into a convenient, useable format.

A systematic review allowed the analysis of all available and relevant evidence in a systematic objective and robust manner, thus increasing the scientific rigour of the research study and the clinical guidelines formulated in this process. Ultimately, these clinical guidelines (which are based on the best available evidence), if implemented, will be able to reduce variations in practice. In Chapter 4 of the study, various practice variations were identified with regard to current nursing practices of professional nurses in the critical care units in the Nelson Mandela Metropole. Evidence-informed guidelines, based on the systematic review, aimed to both standardize care amongst professional nurses in the critical care units and to improve ultimately the quality and safety of care rendered to the mechanically ventilated patient.