Tangela Hales
April 5, 2012
Correlational Critique

Criterion Critique
1. General Overview of the research.
(5 points) The purpose of the Tang et al, (2009) study was to examine fatigue in chronic heart failure patients and its related factors. The aim was to (1) examine the associations among age, gender, New York Heart Association classification (NYHA), Ejection Fraction (EF), beta-blocker use, Hemoglobin (Hb), depression and fatigue in patients with Congestive Heart Failure (CHF) and (2) determine the contribution of physiological and psychological factors to the variance in CHF patients’ fatigue. Fatigue is a common symptom in patients with chronic heart failure, but little is known about this phenomenon. Fatigue for this sample of chronic heart failure patients was significantly predicted by depression, EF, and NYHA.
2. Are the major variables identified and defined conceptually and operationally? Identify the variables of the study and specify their level of measurement (nominal, interval, ordinal, and ratio).
( 5 points) Yes, the major variable was identified and defined conceptually and operationally. The main outcome variable is fatigue, which is the dependent variable.
Conceptual definition: Fatigue- A complex, multifaceted subjective feeling, which involves physical, psychological and activity dimensions.
Operational definition: Fatigue- A common symptom seen with CHF.
Fatigue is multidimensional, and was measured by two scales: Lee’s Fatigue Visual Analog Scales which uses an ordinal level of measurement and a researcher-developed scale, the Tang Fatigue Rating Scale which uses an ordinal level as measurement as well.
The independent variables are EF, NYHA (ordinal data), beta-blocker use and hemoglobin (Hb). The participant’s age is also an independent variable and was the reported age after the participants 18th birthday (ratio). Spearman’s rho was used to assess NYHA (ordinal data) and its correlation to other variables. Pearson product-moment correlation was used to assess correlations among EF, Hb, BDI-II (depression scale), age and TFRS (interval data).
3. How relevant is the conceptual map and/or theoretical framework. Please explain what it means. (10 points) The conceptual framework for the study was derived from the literature. From the literature review, the researchers identified the following gaps: (1) few researchers have studied fatigue in CHF patients, (2) in some of those studies, subjective data from questionnaires were not supported by objective data and (3) only three studies collected both objective data and subjective data, but did not specify the time between lab analysis and collection of fatigue data. To fill the gaps, the authors examined factors related to fatigue in CHF patients by collecting subjective data (i.e. fatigue and depression) and objective data (NYHA, EF, beta-blocker use, hemoglobin level) within three days of the hospital’s routine blood analysis echocardiography. The provided figure in the study illustrates how demographics (age and gender), physiological factors (NYHA, EF, Beta-blocker use, Hb), and psychological factors (depression) all relate to fatigue.
4. Was the appropriate research design used for the study? Provide a rationale for your response. Identify the strengths and weaknesses of the design in addressing the research question. What were the threats to use of this design and how could they have been handled by the researcher? Or, how should they have been handled by the researcher? ( 20 points) Yes, it was an appropriate research design based on the variables and the analysis of the data. The strength of the study is that it did reveal a significant amount of information about fatigue in CHF patients and variables that effect fatigue. The weakness of the study was that the subjects were all hospitalized patients and mostly illiterate (45.8%), preventing generalization of the result to the overall CHF population, especially those residing in the community. Future studies should sample patients from other hospitals, locations and educational backgrounds, thus making the results more representative. The cross-sectional design prevented assessing fatigue patterns over time, so future studies should adopt a longitudinal design.
5. How clearly was the sampling plan described in the study? What were the elements of the sampling plan?( 10 points) Yes, the sampling plan was clear. Patients were included in the study if they met these criteria: (1) CHF diagnosed by a cardiology specialist, (2) age above 18, (3) no past or present psychiatric illness, (4) no past or present neuromuscular disease, (5) can communicate in Chinese and (6) willing to participate in the study and complete the study consent form. Of the 109 patients who met the inclusion criteria, two experienced breathing difficulty and refused to participate, resulting in a sample of 107 subjects. The targeted sample size was determined using Green’s two-step rule of thumb. For a medium effect sample size, the sample size came up to be equal to 71. Thus, at least 71 subjects were required to have enough power to detect significant variance contributed to the fatigue outcome variable by the important correlates, even though the total number of subjects in this study was 107.

6. What ethical precautions did the author follow in the conduct of the study? Was enough done to protect the subjects? (10 points) To ensure that the rights of the human subjects were protected, the research proposal was approved by the medical center’s IRB. Before any data were collected, each potential subject received information about the purpose and procedure of the study and signed an informed consent form. Potential subjects were told that participation was voluntary and that declining to participate would not negatively affect their present or future medical care. Subjects’ confidentiality was addressed in the consent form and they were assured their names would not be identified in publications or reports. According to the study, ethical principles and standards of human rights were adhered to during the entire process.
7. Did the researcher use valid and reliable research instruments? Explain. (10 points) Yes, the researcher used valid and reliable research instruments. One measure of fatigue was the self-report VAS-F (Lee et al, 1991), which includes 18 questions with two-subscales, one for fatigue (13 questions) and one for energy (5 questions). Originally, this instrument was designed as a 100-mm line visual analog scale. For ease of use and convenient data entry, the visual analog format was converted to a numerical rating (Aaronson et al, 1999), which was used in this study. In this study, the VAS-F total scale, energy sub-scale and fatigue sub-scale had internal consistencies, Cronbach’s alpha coefficient of 0.89, 0.97, and 0.89, respectively.
The second measure of fatigue was the TFRS, which was developed by the authors of the study. The 37-item TFRS includes physical, psychosocial and daily-living activity sub-scales, with responses rated on a 1-10 scale. The content was of the TFRS was examined for content validity by three PhD-prepared experts in fatigue, measurement and theory, who recommended adjustments for wording. Because the original TFRS was developed in English, it was translated to Chinese by the first author of the study and back translated by an expert in both Chinese and English to ensure congruency. The TFRS total scale, physiological, psychosocial and daily-living activities subscales had internal consistencies, Cronbach’s alpha coefficient of 0.96, 0.83, 0.92 and 0.97, respectively. As to convergent validity, the TFRS and VAS-F showed significant correlation (r = 0.87, p < 0.01).
Depression was measured by the BDI-II (Beck et al, 1996), which was revised from the original version BDI-IA (Beck et al, 1979). The BDI-II carries a good internal consistency, with a Cronbach’s alpha coefficient of 0.89-0.93 (Krefetz et al. 2002, 2003) and a one-week test-retest reliability of 0.93 (Chen 2000). In this study, the internal consistency, Cronbach’s alpha coefficient was 0.81 for the total scale.
Data was collected form chart review on subjects’ demographic information (age, gender), as well as relevant laboratory and physiological data.
8. Is the method section descriptive enough for you to repeat this study? ( 10 points) The study used a cross-sectional correlation design to recruit a convenience sample of CHF patients from the cardiology ward of a medical center in northern Taiwan. Data was collected between July 2004-January 2005. Patients who met the inclusion criteria agreed to participate and signed informed consent were recruited to the study. These subjects completed questionnaires within three days of the hospital’s routine blood analysis and echocardiography. Out of the 107 subjects, 45.8 were illiterate, so the researcher read out each question for 95.3% of the subjects and recorded their verbal responses. During data collection, nine subjects felt tired and needed a second visit to complete the questionnaires. Most subjects completed questionnaires in one visit. The average time to answer questionnaires was 34 minutes.
9. Were the statistical tests appropriate? Justify your response please. ( 10 points) Yes, the tests used were appropriate for this study. Data was coded and entered using the Statistical Package for the Social Sciences for Windows (SPSS version 13.0). Data was first descriptively analyzed to check the distribution of all study variables. Cronbach’s alpha was used to determine the internal consistency reliability for various measures (VAS-F, TFRS and BDI-II). Descriptive statistics (frequency, percent, mean, standard deviation and actual range) were generated for all measures. Pearson correlations were used to assess the strength of association between fatigue and continuous data (EF, Hb, and depression) with ordinal data. These associations were important to determine threat of collinearity before doing multiple regression analyses. A squared multiple correlation was used to indicate the effect for multiple regression analysis, or relationship with predictor variable. The statistical level of significance was set at 0.05.
10. Please interpret the findings and their relevancy to nursing practice. ( 10 points) The study findings showed that fatigue in CHF patients was related to gender, beta-blocker use, NYHA classification, EF value, Hb value and depression. Health care providers should inform patients using beta-blockers that their energy level may decreases and fatigue patterns should be closely monitored. Since depression was a significant predictor of fatigue in CHF patients, clinician should not ignore its importance in fatigue.
In nursing care, psychological factors are as important as physiological factors to patients’ well-being. Health care providers should therefore pay more attention to the psychological status of patients with chronic heart failure, thus helping them control their fatigue and improve their overall well-being. CHF patient’s moods should be monitored for obvious disturbances; if necessary they should be referred to mental health or psychiatric practitioners for further assessment and proper treatment. These recommendations may improve fatigue management of CHF patients.