METHODOLOGICAL ISSUES IN NURSING RESEARCH
The integrative review: updated methodology
Robin Whittemore PhD APRN
Associate Research Scientist and Lecturer, School of Nursing, Yale University, Connecticut, USA
Kathleen Knafl PhD
Elizabeth N. Gray Distinguished Professor and Associate Dean for Research and Faculty Affairs, School of Nursing, Oregon Health and Sciences University, Oregon, USA
Accepted for publication 16 February 2005
Correspondence:
Kathleen Knafl,
School of Nursing,
Oregon Health and Sciences University,
Portland,
Oregon 97239-3098, USA.
E-mail: knaflk@ohsu.edu
WHITTEMORE R. & KNAFL K. (2005) Journal of Advanced Nursing 52(5), 546–
553
The integrative review: updated methodology
Aim. The aim of this paper is to distinguish the integrative review method from other review methods and to propose methodological strategies specific to the integrative review method to enhance the rigour of the process.
Background. Recent evidence-based practice initiatives have increased the need for and the production of all types of reviews of the literature (integrative reviews, systematic reviews, meta-analyses, and qualitative reviews). The integrative review method is the only approach that allows for the combination of diverse method-ologies (for example, experimental and non-experimental research), and has the potential to play a greater role in evidence-based practice for nursing. With respect to the integrative review method, strategies to enhance data collection and extrac-tion have been developed; however, methods of analysis, synthesis, and conclusion drawing remain poorly formulated.
Discussion. A modified framework for research reviews is presented to address issues specific to the integrative review method. Issues related to specifying the review purpose, searching the literature, evaluating data from primary sources, analysing data, and presenting the results are discussed. Data analysis methods of qualitative research are proposed as strategies that enhance the rigour of combining diverse methodologies as well as empirical and theoretical sources in an integrative review.
Conclusion. An updated integrative review method has the potential to allow for diverse primary research methods to become a greater part of evidence-based practice initiatives.
Keywords: evidence-based practice, integrative review, methodology, nursing
Introduction
An integrative review is a specific review method that summarizes past empirical or theoretical literature to provide a more comprehensive understanding of a particular phe-nomenon or healthcare problem (Broome 1993). Integrative reviews, thus, have the potential to build nursing science, informing research, practice, and policy initiatives. Well-done integrative reviews present the state of the science, contribute
to theory development, and have direct applicability to practice and policy.
Recent evidence-based practice initiatives have increased the need for and the production of all types of literature reviews (integrative reviews, systematic reviews, meta-analy-ses, and qualitative reviews). The proliferation of all types of research reviews during the past decade has contributed to more systematic and rigorous methods. Much has been learned about the methodology associated with combining
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disparate studies into integrated results and conclusions, particularly with respect to systematic review and meta-analyses approaches (Cooper 1998, Greenhalgh 1997). Yet, concern has been raised that these review methods, while important for evidence-based practice, do not include the depth and breadth of nursing research as they overemphasize the randomized clinical trial and hierarchies of evidence (Kirkevold 1997, Evans & Pearson 2001). To date, evidence-based practice initiatives have viewed different types of evidence (i.e. quantitative and qualitative) as mutually exclusive (Evans & Pearson 2001).
The integrative review method is an approach that allows for the inclusion of diverse methodologies (i.e. experimental and non-experimental research) and has the potential to play a greater role in evidence-based practice for nursing. The integrative review contributes to the presentation of varied perspectives on a phenomenon of concern and has been advocated as important to nursing science and nursing practice (Kirkevold 1997, Estabrooks 1998, Evans & Pearson 2001). However, the complexity inherent in combining diverse methodologies can contribute to lack of rigour, inaccuracy, and bias (Beck 1999, O’Mathuna 2000). Meth-ods to enhance data collection (i.e. literature search) and data extraction have been developed (Garrard 2004, Conn et al. 2003); however, methods of analysis, synthesis, and conclu-sion-drawing remain poorly formulated. This is a consider-able issue, as the data extracted from primary articles of diverse methodologies generally consist of a large repertoire of varied data. Explicit and systematic methods for data analysis specific to the integrative review method are needed to protect against bias and improve the accuracy of conclu-sions. In addition, little attention has been paid to issues related to combining empirical and theoretical reports. The purpose of this paper, therefore, is to distinguish the integrative review method from other review methods and to propose methodological strategies specific to the integra-tive review method to enhance its rigour. An updated integrative review method has the potential to allow for diverse primary research methods to become a greater part of evidence-based practice initiatives.
Background
Methods of conducting reviews of the health care literature have been used since the 1970s in an effort to synthesize findings from discrete primary studies and to increase the generalizability of data about a phenomenon (Jackson 1980). Methods to improve rigour continue to evolve because of the complexity of conducting a thorough review (Greenhalgh 1997). While there are commonalities to all current review
methods (meta-analyses, systematic reviews, qualitative reviews, integrative reviews), each has a distinct purpose, sampling frame, definition, and type of analysis (Whittemore 2005a).
Meta-analysis is a research review method that combines the evidence of multiple primary studies by employing statistical methods, thus enhancing the objectivity and validity of findings (Glass 1976). The research design and hypotheses of primary studies need to be very similar, if not identical (Cooper 1998). With the meta-analysis approach, each primary study is abstracted, coded, and entered into a quantitative database. Findings are subsequently transformed into a common metric to calculate an overall effect size. A significant advantage of the meta-analysis method is that adjustment for sample size and study quality can be included in the analysis (Oxman & Guyatt 1988, Broome 1993).
Systematic reviews are research reviews that combine the evidence of multiple studies regarding a specific clinical problem to inform clinical practice and are the method of choice for evidence-based practice initiatives (that is, Cochrane Collaboration). Systematic reviews require a well-specified clinical question, explicit methods, and a compre-hensive search for relevant primary studies (Counsell 1997, Greenhalgh 1997). Systematic reviews often include the statistical methods of meta-analysis if primary studies meet the assumptions required for meta-analyses. If primary studies cannot be combined statistically, a narrative analysis is undertaken in conjunction with vote counting or other quasi-statistical approaches (Cooper 1998).
Numerous methods to combine qualitative research have been developed in the past decade (Jensen & Allen 1996, Sandelowski et al. 1997, Kearney 1998, Paterson et al. 2001, Sandelowski & Barroso 2003). Meta-synthesis, meta-studies, formal grounded theory, and meta-ethnography methods are aimed at synthesizing findings of individual qualitative studies into a new theory or overarching framework on the phenomenon of concern. These distinct methods exclusively synthesize qualitative primary studies, yet differ in approaches to analysis and levels of interpretation. Synthesizing the evidence from multiple qualitative primary studies is complex; however, these methods have the potential to broaden the generalizability of qualitative research.
Integrative reviews are the broadest type of research review methods allowing for the simultaneous inclusion of experi-mental and non-experimental research in order to more fully understand a phenomenon of concern. Integrative reviews may also combine data from the theoretical as well as empirical literature. In addition, integrative reviews incor-porate a wide range of purposes: to define concepts, to review theories, to review evidence, and to analyse methodological
Methodological issues in nursing research Integrative review
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issues of a particular topic (Broome 1993). The varied sampling frame of integrative reviews in conjunction with the multiplicity of purposes has the potential to result in a comprehensive portrayal of complex concepts, theories, or health care problems of importance to nursing.
Yet, without explicit and systematic methods specific to undertaking an integrative review, the risk of error increases exponentially. Systematic bias and error can occur at any stage of the review (Oxman 1994, Dunkin 1996). For example, the literature search stage may be incomplete without consideration of important primary sources. Data from primary sources can be incorrectly extracted and interpreted. Most important, data analysis may be incom-plete or may not be an accurate synthesis of all of the data from primary sources. Analysing and synthesizing varied primary sources is a major challenge in undertaking an integrative review. Thus, developing d