Multivariate Outliers: A Conceptual and Practical Overview for the Nurse and Health Researcher.

The presence of statistical outliers is a shared concern in research. If ignored or improperly handled, outliers have the potential to distort parameter estimates and possibly compromise the validity of research findings. The purpose of this paper is to provide a conceptual and practical overview of multivariate outliers with a focus on common techniques used to identify and manage multivariate outliers. Specifically, this paper discusses the use of Mahalanobis distance and residual statistics as common multivariate outlier identification techniques. It also discusses the use of leverage and Cook's distance as two common techniques to determine the influence that multivariate outliers may have on statistical models. Finally, this paper discusses techniques that are commonly used to handle influential multivariate outlier cases.

Univariate Outliers: A Conceptual Overview for the Nurse Researcher.

The presence of statistical outliers is a shared concern in research. If ignored or improperly handled, outliers have the potential to distort the estimate of the parameter of interest and thus compromise the generalizability of research findings. A variety of statistical techniques are available to assist researchers with the identification and management of outlier cases. The purpose of this paper is to provide a conceptual overview of univariate outliers with special focus on common techniques used to detect and manage univariate outliers. Specifically, this paper discusses the use of histograms, boxplots, interquartile range, and z-score analysis as common univariate outlier identification techniques. The paper also discusses the outlier management techniques of deletion, substitution, and transformation.

Exploring the Impact of Prostate Cancer Radiation Treatment on Functions, Bother, and Well-Being.

Though many studies have explored the effects of radiation therapy on urinary, sexual, and bowel function and/or bother, few have focused on symptom experiences from diagnosis through the first year following completion of radiation therapy. The purpose of this study was to compare the effect of 3 types of radiation treatment on functions, bother, and well-being in men with prostate cancer at 1, 6, and 12 months after completion of treatment. A repeated measures survey (N = 73) found that none of the function, bother, emotional, social, or functional well-being scores were significantly different among the 3 groups. However, within-subjects-only repeated measures ANCOVA suggested that emotional well-being and social well-being are different over time. The findings show that clinical treatment of prostate cancer has an impact on functions, bother, and well-being of patients. Thus, it is important that nurses and other healthcare providers listen to what patients are saying before, during, and after treatment.

Bien que de nombreuses études aient examiné les effets de la radiothérapie sur les fonctions ou les gênes urinaires, sexuelles et intestinales, peu ont mis l'accent sur les symptômes ressentis à partir du diagnostic jusqu'à la fin de l'année suivant le traitement. L'objectif de cette étude était de comparer les effets de trois types de radiothérapie sur les fonctions, les gênes et le bien-être d'hommes atteints d'un cancer de la prostate un mois, six mois et douze mois après la fin du traitement. Un sondage intégrant des mesures répétées (N = 73) a permis de constater qu'il n'y avait pas de variation importante entre les trois groupes quant aux mesures touchant les fonctions corporelles, les gênes physiques ou le bien-être social, émotionnel ou fonctionnel. Toutefois, l'analyse de covariance des mesures répétées touchant les sujets uniquement laisse entendre que le bien-être émotionnel et le bien-être social évoluent dans le temps. Les conclusions de l'étude indiquent que le traitement clinique du cancer de la prostate a une incidence sur les fonctions corporelles, les gênes physiques et le bien-être des patients. Il est par conséquent important que le personnel infirmier et les autres professionnels de la santé prennent le temps d'écouter les patients avant, pendant et après leur traitement.

Testing a model of delayed care-seeking for acute myocardial infarction.

A theory-testing approach to the study of delay in seeking treatment for acute myocardial infarction (AMI) was performed using a descriptive design with 135 AMI patients. Participants provided information pertaining to history of AMI, symptom congruence, responses to symptoms, cardiac symptom attribution, and AMI care-seeking delay. Structural equation modeling fit indices suggested that the independent predictors of AMI care-seeking delay were cardiac symptom attribution and emotion-focused coping. History of AMI had a direct relationship with AMI care-seeking delay, but its total effect through symptom attribution and symptom congruence was not significant. The total effect of symptom congruence on AMI care-seeking delay was significant. In conclusion, the study findings highlight the importance of targeting cardiac symptom attribution and emotion-focused coping in interventions that are aimed at reducing AMI care-seeking delay.

Comparing the psychological stress between non-smoking patients and smoking patients who experience abrupt smoking cessation during hospitalization for acute myocardial infarction: a pilot study.

BACKGROUND: Stress is an untoward condition in patients with acute myocardial infarction (AMI). Abrupt nicotine withdrawal is associated with increased symptoms of stress. However, little is known about the impact of smoking cessation on the psychological indicators of stress among hospitalized AMI patients. PURPOSE: In this pilot study we compared the psychological stressors between non-smoking AMI patients and smoking patients who abruptly ceased smoking following admission to the CCU. METHODS: A cross-sectional survey was piloted on a sample of 57 AMI patients (29 smokers and 28 nonsmokers) on the second day of admission to the CCU. Psychological stress was measured using the Profile of Mood States and the Insomnia Severity Index. RESULTS: Multivariate analysis of covariance (MANCOVA) suggested that after adjusting for age, smokers experienced significantly higher overall levels of stress than non-smokers (F = 3.13; p = 0.016). Post-hoc analyses suggested that scores of depression (p = 0.033), anxiety (p = 0.007), and anger (p = 0.017) were particularly higher among smokers, as compared to non-smokers. However, the two groups were not different with regard to their scores on fatigue (p = 0.528) and insomnia (p = 0.299). CONCLUSIONS: Abrupt smoking cessation may expose patients admitted with AMI symptoms to higher levels of psychological stress. Given the potential damaging impact of psychological stressors on the physical outcomes of these patients, these findings demonstrate the need for continued assessment and research related to the management of nicotine withdrawal following AMI.

Alternative coping strategies and decision delay in seeking care for acute myocardial infarction.

BACKGROUND AND OBJECTIVE: In attempting to manage acute myocardial infarction (AMI) symptoms, individuals often engage in coping strategies that cause them to delay seeking timely medical care. Review of the literature revealed that several coping strategies were examined in relation to AMI delay, but there were no studies investigating the extent of use of each coping strategy. The purpose of this study was to examine the extent of use of 15 coping strategies and their associations with the time taken to decide to seek medical care. SUBJECTS AND METHODS: Secondary data analyses were performed on a sample of 135 patients with AMI from Canada and the United States from whom data were collected via structured interviews. Descriptive analyses were used to identify the extent of use of alternative coping strategies. Spearman rho was used to test the associations of these strategies with decision delay. RESULTS AND CONCLUSIONS: The 3 most frequently used coping strategies were trying to relax, wishing/praying for symptoms to disappear, and discussing symptoms with someone. Nine coping strategies were significantly associated with decision delay. The findings of this study are useful in teaching patients about avoiding the use of coping strategies when faced with AMI symptoms. This can potentially help reduce delays in seeking care for AMI, which will result in better health outcomes for patients with AMI.

Examining the association between chest tube-related factors and the risk of developing healthcare-associated infections in the ICU of a community hospital: a retrospective case-control study.

OBJECTIVES: The study examined the association between chest tube-related factors and the risk for developing healthcare-associated infections (HAI). RESEARCH METHODOLOGY: A case-control retrospective chart review was performed on 120 intensive care patients. Eligible patients were 18 years of age or older, had been in the intensive care unit (ICU) for 48 h or more, and had one or more chest tubes. SETTING: A 20-bed medical-surgical intensive care unit (ICU) of a community hospital in south-western Ontario, Canada. MAIN OUTCOME MEASURES: Documented diagnosis of hospital-acquired pneumonia or bloodstream infection. RESULTS: The variable chest tube days was the only chest tube-related factor that was independently associated with HAI (OR = 5.78; p = 0.013). Mechanical ventilation (OR = 4.88; p = 0.002) and outcome length of stay (OR = 0.72; p < or = 0.001) were also independently associated with HAI. CONCLUSIONS: The risk of infection among patients with chest tubes increases as the number of chest tube days increases. Infection is likely to happen early during admission, which necessitates stringent adherence to infection control strategies, especially during that time frame.

Home intravenous therapy and the ability to perform self-care activities of daily living.

This prospective cohort study examined the variables that affect the ability of 92 patients receiving home intravenous (IV) therapy to perform self-care activities of daily living and whether there was a difference in their ability based on vascular access device (VAD) location and type or other IV-related variables. Analysis revealed that 4 IV-related variables were significant predictors of self-care ability score: IV delivery method (beta = -.212, P = .018), VAD placement in the dominant hand (beta = -.208, P = .017), VAD dressing (beta = .215, P = .013), and IV solution (beta = .206, P = .022). These findings provide community-based nurses with evidence-based information regarding the variables that have an impact on the ability of patients receiving home IV therapy to perform the activities of daily living.

Comparison of coping responses to symptoms between first-time sufferers and those with a previous history of acute myocardial infarction.

BACKGROUND AND OBJECTIVE: Little is known about how experience with a previous acute myocardial infarction (AMI) impacts individuals' reactions to symptoms of a recurrent episode. Thus, the purpose of this study was to compare the use of coping strategies during an acute cardiac event in patients experiencing a first AMI with those experiencing a recurrent AMI. SUBJECTS AND METHODS: Secondary data analyses were performed to examine differences in the use of coping strategies between individuals with and without a history of AMI. Mann-Whitney U test was performed to compare those with (n = 26) and without (n = 109) a previous AMI with respect to 15 coping strategies, each of which was measured on a 5-point Likert scale. RESULTS AND CONCLUSIONS: Patients with a history of AMI were more likely to use prescribed medications to deal with their symptoms than were patients who did not have a previous AMI (M = 1.5 and 0.20; median = 2.0 and 0.0, respectively; P < .001). However, patients who had no previous AMI were more likely to respond by taking nonprescription medications (M = 0.90 and 0.60; median = 1.0 and 0.0, respectively; P = .04). The results suggest that patients with and without a history of AMI tend to respond to their symptoms with similar coping strategies. When differences occurred, patients with and without a history of AMI differed only with respect to the type of self-medication choices they made. Implications pertaining to these findings are discussed.

Nurses' roles with families: perceptions of ICU nurses.

This descriptive survey examined: (a) differences between nurses' (N=47) perceptions of self-performance and that of their colleagues with regard to their roles with family members of intensive care patients, and (b) the impact of nurses' comfort on their role enactment as it relates to family focused interventions. Participants rated their self-performance higher than that of their colleagues with respect to 15 of the 19 items, suggesting that they think they perform better than their colleagues. The results also showed that nurses' comfort was positively correlated with their role enactment as it pertains to discussing patient prognosis (r=.496; p<.001), explaining patient's equipment (r=.43; p=.003), and discussing the possibility of death with family members (r=.43; p=.003).

Methodological issues associated with using different cut-off points to categorize outcome variables.

Knowledge of the factors that contribute to delay in seeking medical treatment for acute myocardial infarction (AMI) provides the basis for interventions that are intended to facilitate prompt care-seeking behaviour. However, operational definitions of delay time vary across research studies. The use of inconsistent cut-off times to distinguish between delayers and non-delayers is likely to compromise comparability and generalizability of the findings across studies. The purpose of this paper is to examine the impact of inconsistent operationalization of delay, in terms of cut-off times, on the validity of research findings pertaining to identifying its predictors. Secondary data analysis was performed using a sample of 73 patients who had recently experienced out-of-hospital AMI and concluded that their symptoms were related to the heart. Several regression models were built to examine the influence of using different cut-off times (1, 2, 3, 6, and 12 hours, median delay) on the number and nature of predictors ofAMI care-seeking delay. The impact of varying cut-off times on the explained variance, sensitivity, specificity, and predictive values associated with each regression model was examined. The use of different cut-off times produced different sets of independent predictors, which varied in number and nature. The variance explained by the different regression models as well as their classification indices varied. Use of different cut-off times for the definition of delay time led to inconsistent results. Thus, it is recommended that criteria be established among clinicians and researchers with regard to operationally defining care-seeking delay for AMI.

Enhancing health-care research: an interdisciplinary collaborative approach.

Many research programs tackle complex problems that cannot be comprehensively investigated by a sole researcher or a research team from a single profession. Interdisciplinary teams can develop a collective mass of common knowledge, broaden the scope of research, and produce more clinically relevant outcomes that are sensitive to the realities of practice. The authors describe the experience of a research team from the perspective of its members. The purposes of the paper are to highlight the benefits of an interdisciplinary collaborative approach to research and to describe the characteristics of a successful team. Some of the benefits discussed include increased research productivity and quality, professional development and mentorship, support and encouragement, expanded resource networks, and bridging of the gap between academia and practice. The authors also discuss the characteristics of a successful research team, associated challenges, and recommendations for enhancing research endeavours through collaboration.

Handling missing data in self-report measures.

Self-report measures are extensively used in nursing research. Data derived from such reports can be compromised by the problem of missing data. To help ensure accurate parameter estimates and valid research results, the problem of missing data needs to be appropriately addressed. However, a review of nursing research literature revealed that issues such as the extent and pattern of missingness, and the approach used to handle missing data are seldom reported. The purpose of this article is to provide researchers with a conceptual overview of the issues associated with missing data, procedures used in determining the pattern of missingness, and techniques for handling missing data. The article also highlights the advantages and disadvantages of these techniques, and makes distinctions between data that are missing at the item versus variable levels. Missing data handling techniques addressed in this article include deletion approaches, mean substitution, regression-based imputation, hot-deck imputation, multiple imputation, and maximum likelihood imputation.

Family perceptions of nurses' roles toward family members of critically ill patients: a descriptive study.

OBJECTIVES: The purpose of this study was to examine the role of the nurse with families of critically ill patients as perceived by family members and whether meeting family expectations impact family satisfaction. METHODS: A descriptive design was conducted with 29 family members from a 19-bed intensive care unit. Nonparametric statistics, known for their appropriateness for small samples, were used to examine the research questions. RESULTS: Overall, the expectations that family members held regarding nurses' roles with families were not different from their perceptions of what nurses actually did (P = .087). Family members were more satisfied with care when nurses' performance either met or exceeded their expectations (P = .046). CONCLUSION: Nurses did well with regard to meeting family members' expectations. Variations in expectations among family members reflect their diversity and highlight the importance of assessing family needs on a case-by-case basis.

Predicting nosocomial bloodstream infections using surrogate markers of injury severity: clinical and methodological perspectives.

BACKGROUND: Injury severity indices are numerical scores that are utilized to predict nosocomial bloodstream infections (BSI) in critically ill patients. However, surrogate markers of injury severity (SMIS) may be more clinically meaningful than these commonly used numerical injury severity indices with respect to the control and prevention of nosocomial BSI. OBJECTIVE: The purpose of this study was to demonstrate the clinical and research implications of using the SMIS in predicting nosocomial BSI. METHOD: A prospective nonexperimental cohort study was conducted on 361 critically ill trauma patients. Three logistic regression models were examined for their clinical relevance and statistical parsimony. The first model included the Injury Severity Score (ISS) and 5 other independent predictors, and excluded the SMIS. The second model included all study variables. The third model excluded the ISS. RESULTS: The analysis suggested that number of blood units transfused, number of central venous catheters inserted, and use of chest tube(s) were the SMIS. The ISS was found to be an independent predictor of nosocomial BSI only when the SMIS were not included in the model. The model that included the SMIS and excluded the ISS explained the highest variance in nosocomial BSI and had the best negative predictive value (93%). DISCUSSION: Clinicians can use knowledge of SMIS to develop interventions that minimize the risk of nosocomial BSI. Hence, the SMIS can serve not only as a prediction tool but also as a way to enhance control and prevention strategies for BSI.

Missing data: an introductory conceptual overview for the novice researcher.

Missing data is a common issue in research that, if improperly handled, can lead to inaccurate conclusions about populations. A variety of statistical techniques are available to treat missing data. Some of these are simple while others are conceptually and mathematically complex. The purpose of this paper is to provide the novice researcher with an introductory conceptual overview of the issue of missing data. The authors discuss patterns of missing data, common missing-data handling techniques, and issues associated with missing data. Techniques discussed include listwise deletion, pairwise deletion, case mean substitution, sample mean substitution, group mean substitution, regression imputation, and estimation maximization.

Severe acute respiratory syndrome: another challenge for critical care nurses.

Severe acute respiratory syndrome (SARS) is a viral disease that may be contracted by exposure to a newly recognized form of the coronavirus. It often manifests through a set of common respiratory symptoms that include fever and nonproductive cough. To date, SARS has no vaccine or definitive treatment. Approximately 20% of SARS patients develop respiratory failure, which requires mechanical ventilation and close cardiopulmonary monitoring. Intensive care unit (ICU) nurses and other healthcare workers who care for SARS patients are at risk of contracting the disease. Thus, it is important that ICU nurses be familiar with the disease and its implications for critical care. This article provides critical care nurses with an update on the first SARS outbreak, its origin, case definition, clinical manifestations, diagnosis, relevant infection control practices, management, and recommendations for the role of ICU nurses in dealing with future outbreaks.