Most of the current medical diagnosis support systems are based on a textual design. In this thesis we present a model that uses a different design. It uses visualization to aid home diagnosis of common diseases in a user-friendly way. The model clearly displays the diagnostic results on the screen. A way of organizing the information into a picture of all symptoms, diseases, and the complex relationships between them (especially the combination of symptoms onto a single screen to give a global view) is presented. The purpose of designing this model is to bring complicated medical knowledge to the ordinary user. We believe that the simplified and economic display can demystify medicine, and empower the user to take better care of himself. By this convenient software tool people can discover quickly at home whether their symptom is serious or not, and then decide whether it is necessary to see the doctor; also people can compare the diagnosis the model makes with the doctors'. This model does not recommend treatment or therapy.

Objective. To compare outcomes in blunt trauma by using Trauma and Injury Severity Score (TRISS) models derived from the Major Trauma Outcome Study (MTOS) and the Ontario Trauma Registry as well as to evaluate the role of the Revised Trauma Score (RTS) within the TRISS model. Methods. Consecutive blunt trauma cases from 11 Level I trauma centres over a 4-year period were identified from the OTR. Coefficients of the Revised Trauma Score were modified using the Ontario data and this score's ability to predict mortality was compared to the Revised Trauma Score derived from MTOS. Two Ontario-specific TRISS models were developed with revised coefficients. The first used the standard Revised Trauma Score and the second used the Revised Score with regenerated coefficients. An expanded TRISS model was developed using all the component variables of TRISS and the Revised Trauma Score using forward step-wise logistic regression analysis. The accuracy of mortality predictions for all models were assessed using a Hosmer-Lemeshow Goodness of Fit statistic as well as by estimating sensitivity, specificity (using probability of survival cutpoint of 50%) and the area under the receiver operating characteristic (ROC) curve. (Abstract shortened by UMI.)

Objectives. (1) To develop a probability trade-off technique (PTOT) for determining the minimal clinically important difference (MCID) of warfarin therapy from the patients' perspective; (2) to estimate the MCID for the efficacy of warfarin to prevent stroke in the treatment of nonvalvular atrial fibrillation (NVAF) from the perspective of patients with this disease and who have experienced a course of warfarin therapy; (3) to assess two different methods of eliciting the patients' MCID. The two elicitation methods were: (1) ping-ponging (PP), in which the hypothetical efficacy of warfarin to prevent stroke was varied from one extreme to the other until the patients' MCID was determined; and (2) starting at known efficacy (SKE), in which the hypothetical efficacy was started at a midpoint value and then incrementally increased or decreased until the patients' MCID was determined. Conclusions. The MCID for this group of patients was much smaller than the known efficacy of warfarin to prevent stroke in patients with NVAF. The PTOT, using the flipchart approach, was well accepted and appeared to improve their knowledge of their disease, and its consequences and treatment. The method of elicitation used to determine the patients' MCIDs can have a clinically important effect on their responses. (Abstract shortened by UMI.)

The introduction of high-dose chemoradiotherapy with autologous peripheral blood stem cell and/or bone marrow transplantation (ABMT) has been used to treat patients with low grade non-Hodgkin's lymphoma who fail to achieve a complete response to standard therapies or who progress after achieving a remission, in an attempt to improve disease-free and overall survival. The introduction of ABMT for the treatment of high-risk low grade non-Hodgkin's lymphoma has introduced an interesting clinical question for patients and physicians. Patients must decide whether the up-front increased morbidity and risk of treatment related mortality (TRM) with an ABMT is worth accepting for an as yet undefined potential benefit over standard salvage therapies (SST). One method of examining the choice between therapeutic options is to determine the minimal clinically important difference (MCID) the patient would require to choose one therapy over its alternate. Many groups have introduced decision aids (DAs) to assist patients in making choices. The primary objective of this study was to describe, using a disease specific DA, the MCID required to choose ABMT over SST in a cohort of patients with high risk low grade non-Hodgkin's lymphoma. (Abstract shortened by UMI.)

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The condition of arteriosclerosis was simulated in male, Wistarstrain rats by sub-diaphragmal aortic constriction. Two days after constriction, a significant (P < 0.05) increase in cardiac mass had occurred. Significant changes in extracellular fluid volume and electrolyte content of the left ventricle, right ventricle and atrium were found much sooner than changes in cardiac mass and may thus play a role as instigating factors in the mechanism of cardiac hypertrophy. The extracellular fluid volume was measured by a radioactive isotope dilution method employing S35-sulphate. Significant increases in sulphate space and sodium content were found to occur in the left ventricle within 24 hours after aortic constriction. These increases became even more significant (P < 0.001) at 10 days, then both parameters decreased to within normal range between 2 and 3 weeks after aortic constriction. Close correlation (r = 0.915) was found between sulphate space and sodium content in both ventricles of hypertrophied hearts. Total water remained remarkably constant in the left ventricle but rose significantly in the right ventricle of hearts with the greatest degree of hypertrophy (over 66% increase). Potassium content remained unchanged in the left ventricle but dropped significantly in the right ventricle, as did total phosphate. The same parameters were measured in different regions of normal hearts of unoperated, 150 to 450 gram rats. It was found that sulphate space, total water, sodium content, intracellular potassium, etc. all reached maximal values in the 250 to 300 gram rats and then all (except sodium) decreased in larger rats. Because this weight group occurs at the steepest part of the normal growth curve, these changes in water and electrolyte values are thus associated with rapid normal growth as well as with the accelerated growth of cardiac hypertrophy. Possible reasons for the observed changes in water and electrolyte balance are discussed from the point of view of hormonal, metabolic, hemodynamic and physical changes.

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Background. Bystander CPR is associated with improved survival from cardiac arrest, the first cause of mortality in Canada. Objectives. To improve bystander CPR rates and survival from out-of-hospital cardiac arrest. Methods. A retrospective and prospective analysis of data on cardiac arrest, a systematic review of bystander CPR, a trial designed for improving survival from out-of-hospital cardiac arrest. Results. 7707 out-of-hospital cardiac arrests (1995--2000) with bystander CPR rate (16.5%) and overall survival to discharge (4%). Cardiac arrests are in residential locations (84.7%). Increasing bystander CPR rates could significantly improve survival in residential dwellings (OR 3.6; 95%CI 2.9--4.6). We systematically reviewed 221 publications to plan the intervention for our suggested cluster randomized trial. The study is feasible over a 3 to 5-year period. Conclusions. Public health intervention in the field of bystander CPR will improve survival from cardiac arrest. Our study could significantly affect other international communities equipped with an existing EMS.