Contrast Echocardiography Cost Effectiveness for Left Ventricular Thrombus Assessment

Decision analysis techniques will be utilized to construct and estimate a model for the
diagnosis, treatment, outcomes and costs among patients with dilated or ischemic
cardiomyopathy referred for clinically indicated rest transthoracic echocardiography. We
will first perform a systematic review of the literature regarding the use of contrast
echocardiography for detection of LV thrombus, in order to ensure that model design
accurately reflects clinical practice and current outcomes. Patients will begin the model in
a state of dilated or ischemic cardiomyopathy with possible LV thrombus, and will progress
through the model's various health states based on event probabilities that will be
influenced by whether the patient received contrast during their initial echocardiogram. The
probability of events occurring (e.g., stroke, bleeding complication, death) will be
estimated using data from the literature and the DEDUCE database. The cost of inpatient,
outpatient, and extended care for health states will be derived from available sources,
including Medical Expenditure Panel Survey data, National Nursing Home Survey data, and
published literature. Appropriate statistical methods, including inverse probability
weighted partitioned estimators, will be used to correctly impute long-term resource
utilization, given that the data include patients who are censored due to loss to follow-up.
Quality of life adjustment factors for health states will be drawn from the literature. For
temporary event states such as bleeding, a utility decrement will be subtracted from the
baseline utility value.

The model will have a long-term horizon, and model outcomes will include long-term costs as
well as QALYs. There will be a number of scenario analyses to evaluate alternative modeling
assumptions. For example, we will simulate the selective use of contrast in only those
patients with a technically inadequate study versus the routine use of contrast in the
primary analysis. We will also evaluate cost-effectiveness from alternative perspectives
(U.S. health care system; provider; payer), under various reimbursement schemes of interest
(e.g., fee-for-service; accountable care organization setting) and assuming short term time
horizons (e.g., index episode of care through 90 days after testing; three year horizon). We
will also test the model's robustness through a series of sensitivity analyses. These will
include univariate (one-way) sensitivity analyses in which we will assess the model's
robustness to alternative values of each input parameter individually. Examples of
parameters for which sensitivity analyses will be conducted include costs, thrombus
incidence, and event rates. In addition to univariate sensitivity analyses, we will also
perform probabilistic (many-way) sensitivity analyses in which we use Monte Carlo methods to
assess the model's global stability. Cost-effectiveness acceptability frontiers will be
generated to illustrate model sensitivity. All modeling will be performed in a manner
consistent with current International Society for Pharmacoeconomics and Outcomes Research
Good Research Practices guidance. In order to incorporate variability in willingness-to-pay
thresholds in United States payers, we will report our results across a range of
cost-effectiveness thresholds from $50,000 - $200,000 per QALY, with $100,000 per QALY
pre-specified as the primary threshold.

Inclusion Criteria:

- EF within last 3 months of <=35%

Exclusion Criteria:

- <6 months life expectancy