Diss. Linköping : Univ., 2001.

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INTRODUCTION: The ever-changing landscape of the US health care system is characterized by innovation and high-level care, yet it remains in a state of crisis. With the system seemingly locked in this dire state of rising costs, it becomes increasingly important to take costs into account when deciding between multiple treatments for a particular disease by undertaking cost-effectiveness analysis (CEA) studies. In the present study, a model for mitral regurgitation (MR)—a cardiac valvular disease for which multiple treatment options exist with varying degrees of effectiveness, making it a suitable candidate for CEA —was developed to determine the cost-effectiveness of the four main treatments of medical therapy (MT), mitral valve repair (MVR), mitral valve replacement with a mechanical valve (MVPm) and mitral valve replacement with a bioprosthetic valve (MVPb). The goal of the present undertaking was to determine the most cost-effective treatment option for a reference patient given patient-specific inputs to test the functionality of the developed model. METHODS: Input values for costs, probabilities of event’s occurrences and quality-adjusted life-year (QALY) estimates for each treatment option were first obtained from databases and relevant literature. These values were then standardized to account for source variability and input into a decision tree (DT) model created specifically for the present analysis that included branches for each of the four potential interventions, from each of which were three potential outcome arms representing the potential endpoints of each treatment: death, alive with complications and alive without complications. The costs, probabilities and QALY –values of each of the four complications of interest in the study—atrial fibrillation (AFib), stroke, congestive heart failure (CHF) and reoperation—were combined and averaged to create a unified endpoint for the alive with complications branches of the DT. Following the development of the model, the relevant cost, probability and utility values were used to run a simulation to test the functionality of the model using values associated with a fictional 65-year-old Medicare-covered patient with chronic MR to act as a representative of a sizable real-life population. The model results were then used to calculate the incremental cost-effectiveness ratio (ICER)—the standard comparison used in CEA—between treatment options to determine the most cost-effective among them. Following this simulation, one-way sensitivity analyses (SA) were conducted to determine the susceptibility of the result to variations in select input values. RESULTS: The probability-weighted costs of MT, MVR, MVPm and MVPb were found to be $40,387, $60,249, $76,293 and $74,320, respectively, with respective probability-weighted QALYs of 4.298, 4.740, 4.428 and 5.119. The calculation of ICERs from these values led to the conclusion that MVPb dominated all other treatments and had an ICER of $41,370/QALY gained over MT, which was treated as the baseline treatment option. The societal willingness-to-pay (WTP) threshold used in the present study ($62,000/QALY gained) was greater than the ICER, indicating that MVPb is a cost-effective solution to society. The results of the SA indicated that variations in mortality rate within the ranges in the relevant literature have significant effect on the cost-effectiveness of the interventions, with roughly a 4.74% increase in mortality for MVPb or a 5.09% decrease in the rate of MT leading MVPb to be considered cost-ineffective. CONCLUSIONS: The simulation study concluded that for the 65-year-old reference case, MVPb was the most cost-effective option and the additional cost to society was deemed less than society’s WTP for the additional health benefit. The successful simulation of the model indicates it may hold real-world potential and be applicable to numerous other situations with varying input values. Further research into more accurate input values for a larger number of variables need to be determined in order to increase the accuracy and maximize the applicability of the present model. In addition, the model will require further complication via the inclusion of an increasing number of variables to allow for a more accurate determination of cost-effectiveness in a wider range of health scenarios. Thus, the current model described here and a further evolved future model hold great potential for use all across health care in order to help contain rising costs plaguing the current health care system in the United States.

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Myxomatous mitral valve disease (MMVD) is the most common heart disease in dogs. However, prospectively acquired data describing the natural history and prognostic factors in a large population of dogs affected by this disease are sparse. Thus, the Longitudinal Outcome of canine (K9) myxomatous mitral valve disease registry (LOOKmitral) was established to prospectively collect clinical and diagnostic data from a large population of dogs affected by MMVD. A total of 6,102 dogs were enrolled in the LOOK-mitral registry from November 1st, 2015, to October 31st, 2018, in thirteen cardiology specialty practices. We first described the baseline characteristics of the dogs enrolled in the registry, which mainly confirmed previous findings. Moreover, we provided new additional results, such as the presence of systolic dysfunction in some small breed dogs and how the intensity of the murmur correlates with the severity of MMVD also in large breed dogs. Second, we described the baseline treatment characteristics at the time of enrollment. These data showed that the results of the "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly" (EPIC) trial and left atrial and left ventricular dimensions, assessed by echocardiography, influenced veterinary cardiologist's prescription of cardiovascular drugs in affected dogs. Lastly, we evaluated predictors of reoccurrence of congestive signs within 180 days after successfully treating the first episodes of heart failure in dogs enrolled in the LOOKMitral registry. While this study failed to identify accurate predictors of recurrence, dogs with larger left ventricular internal dimensions at end-diastole were more likely to present with reoccurrence of clinical signs suggesting that closer monitoring of these dogs may be recommended. / Doctor of Philosophy / Despite being the most common heart disease in dogs, data on a large group of dogs affected by myxomatous mitral valve disease (MMVD) are currently sparse in veterinary medicine. The Longitudinal Outcome Of canine (K9) Mitral valve disease (LOOK-Mitral) was established in 2015 to collect data on a large population of dogs affected by MMVD. A total of 6,102 dogs were enrolled in thirteen referral centers over three years. First, the baseline characteristics of dogs enrolled in the registry were described. These data mainly confirmed previous findings. Moreover, they provided some new insight like the possible presence of contractile dysfunction in some small breed dogs and the correlation between the intensity of the heart murmur and the severity of the disease also in large breed dogs. Second, we described the medical treatment prescribed or modified by veterinary cardiologists at the enrollment visit. These data showed that the "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly" (EPIC) trial, a clinical trial published during the enrollment period, and the heart ultrasound (echocardiography) data influence cardiologist prescription habits. Lastly, we evaluated if any clinical or echocardiographic variable could predict the reoccurrence of clinical signs of heart failure within 180 days from the first manifestation of those clinical signs in dogs enrolled in the LOOK-Mitral registry. While this study failed to accurately identify predictors of reoccurrence, dogs with larger left ventricular chamber sizes were more likely to present reoccurrence of clinical signs suggesting that closer monitoring of these dogs may be recommended.

Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced congestive heart failure and prolonged QRS duration, aiming at correcting dyssynchrony in the left ventricle (LV). Apart from the beneficial effects on cardiac function and LV reverse remodeling, reduction in functional MR has been observed by Doppler echocardiography after CRT. On the other hand, functional mitral regurgitation (MR) in fact varies over the cardiac cycle that a biphasic pattern has been reported, i.e. early- and late-systolic peaks with a mid-systolic decrease in regurgitant flow. Nevertheless, it remains to be explored whether (1) the improvement of MR leads to a greater extent of LV reverse remodeling; (2) the different components (i.e. early- and late-systolic) of MR improve and their predictors if any. / Despite comparable ejection fraction, higher degree of functional MR was associated with further impairment in short-axis myocardial deformation (circumferential and radial), but not with long-axis myocardial deformation. The degree of LV basal rotation was also lower in the MR patient group. Furthermore, the decrease in myocardial deformation was associated with greater extent of LV remodeling. / In conclusion, LV global mechanical dyssynchrony play a role in determining the severity of functional MR in addition to mitral leaflet tenting in patients with LV systolic dysfunction. Functional MR is associated with further impairment of myocardial deformation, but with differential change in individual component of myocardial deformation. CRT reduces functional MR in both early- and late-systolic phases, by way of improvement in LV remodeling, LV dyssynchrony and mitral leaflet tenting. Meanwhile, the improvement of MR contributes to LV reverse remodeling after CRT. (Abstract shortened by UMI.) / The improvement of functional MR was an independent predictor of LV reverse remodeling after CRT. The extent of LV reverse remodeling (reduction of LV end-systolic volume) was greatest in patients with improvement of MR, followed by those with "mild or no" MR at baseline, and was least in those without improvement of MR. CRT reduced functional MR by reducing both its early- and late-systolic components in heart failure patients. The reductions in LV end-systolic volume and dyssynchrony were related to the improvement of early-systolic MR, while the improvement of late-systolic MR was attributable to the reductions in mitral leaflet tenting and LV dyssynchrony. / The main findings were as follows: LV global systolic dyssynchrony served as an independent predictor for the presence of significant functional MR in patients with LV systolic dysfunction. Although mitral valvular tenting area was the most powerful predictor, LV global systolic dyssynchrony added incremental value to mitral valve tenting area in predicting the presence of significant functional MR. / We performed echocardiography with TDI and 2DSTE in 147 patients of both ischemic and non-ischemic etiologies with LV systolic dysfunction (defined as LV ejection fraction <50%) and 45 normal controls. MR severity, displacement of papillary muscle, mitral annular dilation and dysfunction, mitral leaflet tenting, LV remodeling and function were assessed by 2D and Doppler echocardiography. LV mechanical dyssynchrony indices were derived from TDI velocity. Myocardial strain (i.e. amount of deformation) in longitudinal, circumferential and radial directions and torsion (opposite rotational movement between apex and base of the heart) were measured by 2DTSE. / Liang, Yujia. / "October 2009." / Adviser: Cheuk man Yu. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 169-193). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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Thesis (Ph. D.)--University of New South Wales, 2002.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [127]-138).