Hinderliter, A. L., Babyak, M. A., Sherwood, A., & Blumenthal, J. A. (2011). The DASH diet and insulin sensitivity. Current Hypertension Reports, 13, 67-73.
Research Problem/Purpose
The researchers have identified high blood pressure as one of the underlying risk factors for cardiovascular disease. The authors have indicated that hypertension increases the risk of diabetes and insulin resistance. In addition, the article has illustrated how the combination of diabetes and high blood pressure predisposes patients to multiple illnesses. These medical conditions include coronary heart disease, heart failure, stroke, and chronic kidney disease (Hinderliter, Babyak, Sherwood, & Blumenthal, 2011). According to Hinderliter et al., these conditions constitute the adverse effects of hypertension. Thus, the identified problem has established the basis that maps the direction of the article.
The investigators have used the introduction section to contextualize the problem within the framework of the existing knowledge. Thomas and Harden (2008) have asserted that an excellent introduction provides the foundation for the research article. For instance, Hinderliter et al. have identified the limitations of antihypertensive medications in treating high blood pressure. The inclusion of this information in the introduction has justified lifestyle modifications. Hinderliter et al. have explored this issue further by citing examples from the Joint National Committee’s seventh report (JNC-7). The findings from the JNC-7 report have shown how the adoption of healthy behaviors reduces the risk of hypertension. This information has framed the research question and purpose in context.
The purpose of this review was to evaluate the combined and independent effects of different lifestyle modifications on insulin insensitivity and blood pressure. The interventions included the DASH diet, as well as physical activity and weight loss. The authors included the aspects of weight loss and exercise in the study because the baseline research had specifically recommended the DASH diet to lower high blood pressure. The findings from this review will solve a nursing problem because it will validate behavior modification as one of the preventive measures for high blood pressure. According to Peterson, Gaziano, and Greenland (2014), hypertension is a significant risk factor for a myriad of diseases. As such, it is imperative to prevent the onset of this condition.
Review of the Literature
The literature review of research supports the phenomenon under study by analyzing the previous studies and models in the area of interest (Beck, 2013). The article has not provided a dedicated section to review the literature. Nonetheless, the authors have identified three thematic areas in their discussions. First, the researchers have examined the correlation between lifestyle modifications and the risk of insulin sensitivity and diabetes. Second, the researchers have explored the influence of the DASH diet plan on blood pressure. Finally, they have also measured the effect of this diet on insulin sensitivity. The references included in this review are from both the previous and current studies. Incorporating the two groups of studies into the article was essential to examine how past practices are influencing the present.
Theoretical Framework
The inclusion of a theoretical framework in a study provides fundamental clues regarding the possible answers to the research question (LoBiond-Wood & Haber, 2013). The authors have not provided a conceptual framework to guide this review. The Health Belief Model (HBM) would have been an appropriate theory for this review. This model identifies the perceived susceptibility, severity, benefits, and barriers that influence people’s decisions to adopt a healthy lifestyle (Yates, Davies, Gorely, Bull, & Khunti, 2009). The authors should have included this theoretical framework to determine how health beliefs affect the adoption of lifestyle modifications. Conversely, Thomas and Harden (2008) have argued that the purpose of systematic reviews is not to test any theory but to generate them instead.
Variables/Hypotheses/Questions/Assumptions
The independent variables in the review were blood pressure and insulin sensitivity. On the other hand, the dependent variables included the DASH diet plan, weight loss, and exercise. The rationale for the preceding statements is that the DASH diet, weight loss, and physical activity affect blood pressure and insulin sensitivity. In contrast, high blood pressure and insulin sensitivity may motivate people to adopt lifestyle modifications. Keele (2011) has asserted that the manipulation of dependent variables may influence the dependent variables and vice versa. It is imperative to note that the researchers did not identify these components explicitly. In addition, they have not provided the operational definitions and measures of these variables.
The authors have stated neither the research question nor the hypothesis in precise terms. Farrugia, Petrisor, Farrokhyar, and Bhandari (2010) have argued that research questions frame the study within the appropriate context. In addition, Farrugia et al. have posited that the hypothesis influences the formulation of the thematic question. Conversely, the purpose of the review provides an indirect link to the research question. Accordingly, the research question would have been, do lifestyle modifications reduce the risk of blood pressure and insulin sensitivity?
Methodology
The purpose of the methods section is to provide sufficient information, which facilitates the replication of the study findings in external settings (Coughlan, Cronin, & Ryan, 2007a). LoBiond-Wood and Haber (2013) have indicated that the components included in the methods section determine whether the chosen design is appropriate to meet the research objectives and answer the research question(s) efficiently. The authors employed the systematic review design using both quantitative and qualitative methods. The researchers used the deductive reasoning approach to generate accurate information from the ENCORE and other studies. The authors intended to confirm the findings reported in both the ENCORE study and the JNC-7 report.
The authors have not indicated the number of studies they reviewed in this analysis. In addition, the reviewers have not identified the sampling techniques they used to select the studies. Thus, it is difficult to determine if they used the probability or non-probability sampling methodologies. Despite these limitations, the reviewers have included the sample size and sampling procedures of the studies included in the review. The inclusion of this information in this review was essential to determine the rigor of the original studies. Further, the authors have provided the setting for the previous studies, which is critical to facilitate the generalization of the combined results.
Although the authors have not provided their data collection procedures, they have identified the ones used in the previous studies. Some of these tools included interviews, surveys, and observations. Coughlan, Cronin, and Ryan (2007b) have reported that interviews and observations are crucial tools for collecting both qualitative and quantitative data. The significance of observations and interviews is that they provide subjective data about the subjects and study settings. Conversely, individual biases might affect the validity and reliability of the findings. The review did not conform to any ethical considerations because it did not include human subjects. The authors did not seek approval from the review board to conduct this review.
Data Analysis
The choice of appropriate data collection and analysis techniques is a crucial step in research processes (Coughlan, Cronin, & Ryan, 2007a). Despite this fact, the researchers have not identified the tools or models they used to analyze their findings. The authors have presented their studies under three themes. First, they have evaluated the effects of exercise and weight loss on the development of diabetes and insulin sensitivity. Second, the researchers have explored the influence of the DASH diet plan on blood pressure. Finally, they have also measured the effect of this diet on insulin sensitivity in patients who have a higher risk of diabetes.
The purpose of this review was to evaluate the combined and independent effects of different lifestyle modifications on insulin insensitivity and blood pressure. The researchers conducted this review based on the findings from the ENCORE study. The researchers have found out that the DASH diet and weight management reduced the level of glucose. This finding was consistent with the one in the ENCORE study, as well as the other studies included in the review. In addition, the authors also found out that the DASH diet recommended in the JNC-7 report lowered blood pressure significantly. The researchers have validated these results in the review.
Summary/Conclusions, Implications & Recommendations
One of the principal strengths of this research is that the researchers have conducted a systematic and extensive literature search. The reviewers used the data published recently in the ENCORE study. The use of the ENCORE study as a reference was essential to validate the results generated in the preceding research. Another advantage of this review is that the results will be extrapolated and generalized to the broader population. Beck (2013) has asserted that the combination of findings in a systematic review facilitates the generalization of the results to the general population more compared to individual studies. In essence, the researchers have used the findings from multiple studies to corroborate those presented in the ENCORE study.
Conversely, Hinderliter et al. have not provided explicit inclusion and selection criteria. In the same vein, they have not revealed if they used a transparent approach to select the articles for review. LoBiond-Wood and Haber (2013) have argued that selection bias may affect the validity and reliability of the results. For example, the authors have not specified if one or more researchers assessed each study. Consequently, personal preferences and prejudices may have had an adverse influence on the selection of the studies. Secondly, the limitations of each study included in the review may have affected the reliability of this review. For instance, the non-responder biases and low response rates of the surveys included in the analysis could have influenced the rigor of the findings.
The researchers have found out that the DASH diet plan lowers blood pressure that has surpassed the optimal level. In addition, the combination of diet and physical activity reduces the risk of diabetes in vulnerable individuals. Diabetes and hypertension are lifestyle conditions that have unfavorable clinical implications (Yates et al., 2009). Thus, the findings from this review support the promotion of lifestyle and diet modifications to reduce or prevent the incidences of these diseases. Nurses and other health care providers should use this evidence to promote the best clinical practices.
References
Beck, T. C. (2013). Critiquing qualitative research. AORN Journal, 90(4), 543-554.
Coughlan, M., Cronin, P., & Ryan, F. (2007a). Step-by-step guide to critiquing research. Part 1: Quantitative research. British Journal of Nursing, 16(11), 658-663.
Coughlan, M., Cronin, P., & Ryan, F. (2007b). Step-by-step guide to critiquing research. Part 2: Qualitative research. British Journal of Nursing, 16(12), 738-744.
Farrugia, P., Petrisor, B. A., Farrokhyar, F., & Bhandari, M. (2010). Research questions, hypotheses and objectives. Canadian Journal of Surgery, 53(4), 278-281.
Keele, R. (2011). Nursing research and evidence-based practice: Ten steps to success (3rd ed.). Sudbury, MA: Jones and Bartlett.
LoBiond-Wood, G., & Haber, J. (2013). Methods and critical appraisal for evidence-based practice (8th ed.). London: Elsevier.
Peterson, E. D., Gaziano, J. M., & Greenland, P. (2014). Recommendations for treating hypertension: What are the right goals and purposes? JAMA, 311(5), 474-476.
Thomas, J., & Harden, A. (2008). Methods for the thematic synthesis of qualitative research in systematic reviews. BMC Medical Research Methodology, 8, 45-49.
Yates, T., Davies, M., Gorely, T., Bull, F., & Khunti, K. (2009). Effectiveness of pragmatic education program designed to promote walking activity in individuals with impaired glucose tolerance. Diabetes Care, 32(8), 1404-1410.