http://hdl.handle.net/1974/810 Sun, 26 May 2013 07:10:23 GMT 2013-05-26T07:10:23Z http://hdl.handle.net/1974/7996 Title: Optimizing Nutrition Therapy in the Intensive Care Unit Through the Evaluation of Barriers to Enterally Feeding Critically Ill Patients Authors: Cahill, Naomi Abstract: The purpose of this thesis was to determine the feasibility of implementing an intervention tailored to overcome barriers to adherence to recommendations of critical care nutrition guidelines in the Intensive Care Unit (ICU). The thesis is comprised of four manuscripts. The first manuscript described the development of a 26 item questionnaire rating the importance of potential barriers as impediments to the provision of enteral nutrition (EN) in the ICU. Preliminary evaluation demonstrated acceptable face and content validity and internal reliability, but the test retest reliability and within group reliability were poor for some items. The second manuscript provided evidence to support the construct validity of the developed questionnaire by reporting the results of a multilevel multivariate regression analysis of cross-sectional data from 55 ICUs that demonstrated that a 10 point increase in the overall barrier score was associated with a statistically significant 3.5% (Standard Error (SE) 1.3) decrease in prescribed calories received from EN. The third manuscript provided data to inform whether the intervention should be tailored to site specific barriers by describing the barriers to enterally feeding critically ill patients identified by 138 nurses, and evaluating whether these barriers differed across the 5 participating sites. Statistically significant differences were found among ICUs for 4 out of the 22 potential barriers. The fourth manuscript described the results of a pretest posttest study involving 5 ICUs in North America and determined that all participating sites successfully developed the tailored intervention. A statistically significant 10% (Site range -4.3 to -26.0%) decrease in overall barriers score, and a non-significant 6% (Site range -1.5 to17.9%) change in prescribed calories received was observed following the intervention. However, there was variability in the degree of implementation achieved by each site. Taken together, the results of this thesis demonstrated that adopting a tailored approach to improving nutrition practice is feasible. However, the findings also resulted in revisions to the barriers questionnaire and modifications to the design of the tailored intervention. Thus, the next step is to formally test the hypothesis that a tailored intervention designed to address barriers to feeding critically ill patients will improve nutrition performance. Description: Thesis (Ph.D, Community Health & Epidemiology) -- Queen's University, 2013-04-28 21:37:54.695 Tue, 30 Apr 2013 04:00:00 GMT http://hdl.handle.net/1974/7996 2013-04-30T04:00:00Z http://hdl.handle.net/1974/7801 Title: Determinants of non-uptake of the quadrivalent HPV vaccine; The Ontario Grade 8 HPV Vaccine Cohort Study Authors: Remes, OLIVIA Abstract: Background: In 2007, the Canadian federal budget provided $300 million over three years to the provinces and territories to implement publicly-funded HPV immunization programs. Current estimates indicate that HPV vaccine uptake varies significantly across Canada and is reported to be lowest in Ontario at 53%. There is a paucity of literature on the determinants of HPV vaccine uptake in the Canadian context, therefore further research is needed. Objectives: To describe the patterns of HPV vaccine non-uptake across health units in Ontario, and identify the individual- and health unit (ecologic)-level factors that influenced HPV immunization decision-making between 2007 and 2011. Methods: The study linked administrative health and immunization databases to identify a retrospective population-based cohort of 144,047 girls eligible for Ontario's school-based HPV immunization program between 2007 and 2011. In this study a girl was considered vaccinated if she received at least 1 dose, otherwise she was considered unvaccinated. Ecologic or health unit-level factors that may have influenced HPV vaccine decision-making were assessed, as well as individual-level predictors including clinical characteristics and sociodemographics. A population-average model based on generalized estimating equations was used to identify determinants associated with non-uptake. Results: In all, 49.3% of girls from 21 public health units refused HPV immunization between 2007 and 2011. Non-uptake varied across health units, from 41.82% to 60.30%. In multivariate analyses, non-uptake was strongly associated with a history of autism (OR=1.60; 95% CI 1.34, 1.90) and Down's syndrome (OR=1.37; 95% CI 1.16, 1.63), refusal of mandatory and optional vaccines (OR=2.23; 95% CI 2.07, 2.4, and OR=3.96; 95% CI 3.87, 4.05, respectively), and infrequent physician visits (OR=1.45; 95% CI 1.35, 1.55). Contextual or health unit-level characteristics appeared to have a weak influence on vaccine decision-making. Conclusions: HPV immunization could lead to a lower risk of developing and dying from HPV-related cancers; however, non-uptake of this vaccine is high. Concerted efforts are needed to reduce missed opportunities during medical consultations, to refine communication strategies and activities to address the information needs of special groups, as well as to develop cross-sectoral collaborations to support the delivery of publicly-funded HPV immunization to schools across Canada. Description: Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2013-02-01 19:49:17.262 Mon, 04 Feb 2013 05:00:00 GMT http://hdl.handle.net/1974/7801 2013-02-04T05:00:00Z http://hdl.handle.net/1974/7790 Title: THE RISK OF MISCARRIAGE FOLLOWING IMMUNIZATION OF THE BIVALENT HUMAN PAPILLOMAVIRUS (HPV) - 16/18 VACCINE: A BAYESIAN APPROACH Authors: FANG, TIAN Abstract: Background: Cervarix is a prophylactic vaccine used in preventing cervical cancer associated with human papillomavirus types 16/18. A previous study that investigated the risk of miscarriage associated with this bivalent vaccine by pooled analysis of data from two clinical trials, showed a numerically higher but statistically insignificant miscarriage rate in the HPV arm for pregnancies that began within three months following the vaccination. We explored this issue using an alternative statistical approach. Objectives: To develop a hierarchical Bayes model to identify the potential time-dependent risk window of miscarriage rate associated with the bivalent HPV vaccine. Methods: This study comprised the development of a hierarchical Bayes Model with its model inference and the application of this model to a real-world question. A multivariate logistic model was proposed that involved an indicator variable to accommodate a risk window with lower and higher cut-off points. Gibbs Sampling algorithms were used for the inference on the parameters of interest. Over ninety sets of simulation studies were conducted to evaluate the performance of the proposed method and estimate the power in detecting the risk effect. The Bayesian approach was then compared to the existing traditional approaches (e.g. the permutation test). The proposed model was applied to the subpopulation of pregnant women from the Costa Rica Vaccine Trial. Results: In simulation studies, the Bayesian model demonstrated a better performance over the traditional approaches. It showed higher power than the traditional hypothesis testing in detecting the risk effect; it was more informative than the permutation test because it provided both the point estimates and the corresponding credible intervals for the cut-points and the ratio of odds ratios. In the analysis of the CVT data, we observed an effect of 1.13 (95% credible interval: 0.49 to 2.75), implying no significant evidence to support the hypothesis that HPV is associated with a higher miscarriage rate. Conclusions: The hierarchical Bayes model can be applied to investigate the time-dependent risk of adverse events in clinical trials. Using the new Bayesian method, no significant risk of miscarriage in the Costa Rica Vaccine Trial was established, which is consistent with previous report. Description: Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2013-01-30 23:20:39.859 Thu, 31 Jan 2013 05:00:00 GMT http://hdl.handle.net/1974/7790 2013-01-31T05:00:00Z http://hdl.handle.net/1974/7689 Title: An Investigation and Review of Futility Analysis Methods in Phase III Oncology Trials. Authors: Winch, Chad Abstract: The general objective of this thesis was to improve understandings of design, conduct and analysis of randomized controlled trials (RCTs). The specific objective was to evaluate the methodological and statistical principles associated with conducting analyses of futility, a component of interim analysis, as part of the conduct of RCTs. This objective was addressed by first performing a systematic review, which included a detailed literature search, as well as data from a cohort of previously extracted studies. The systematic review was designed to identify futility analysis principles and methodologies in order to inform the design and conduct of retrospective futility analyses of two completed NCIC CTG trials. The results of these trials have been previously published; one trial met its stated endpoint and the other did not. Neither trial underwent an interim analysis of futility during its conduct. The retrospective futility analyses assessed the accuracy of frequently used methods, by comparing the results of each method to each other and to the original final analysis results. These assessments were performed at selected time points using both aggressive and conservative stopping rules. In order to increase the robustness of the comparisons, bootstrapping methods were applied. The results of this thesis demonstrate principles associated with the conduct of futility analyses and provide a basis for hypotheses-testing of optimum methodologies and their associated trade-offs. Description: Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2012-12-12 13:10:15.619 Wed, 12 Dec 2012 05:00:00 GMT http://hdl.handle.net/1974/7689 2012-12-12T05:00:00Z