1 Sixty-Four-Slice Computed Sixty-Four-Slice Computed Tomography of the Coronary Tomography of the Coronary Arteries: Cost- Arteries: Cost- Effectiveness Analysis of Effectiveness Analysis of Patients Presenting to the Patients Presenting to the ED with Low Risk Chest Pain ED with Low Risk Chest Pain Rahul K. Khare, MD Rahul K. Khare, MD Institute for Healthcare Institute for Healthcare Studies Studies Department of Emergency Medicine Department of Emergency Medicine Feinberg School of Medicine Feinberg School of Medicine Northwestern University Northwestern University [email protected][email protected]
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Sixty-Four-Slice Computed Sixty-Four-Slice Computed Tomography of the Coronary Tomography of the Coronary Arteries: Cost-Effectiveness Arteries: Cost-Effectiveness
Analysis of Patients Presenting to Analysis of Patients Presenting to the ED with Low Risk Chest Painthe ED with Low Risk Chest Pain
Rahul K. Khare, MDRahul K. Khare, MD
Institute for Healthcare Studies Institute for Healthcare Studies
Department of Emergency MedicineDepartment of Emergency Medicine
Feinberg School of Medicine Feinberg School of Medicine
Chest Pain In the Chest Pain In the Emergency DepartmentEmergency Department
““Chest Pain” Chest Pain” Most common Emergency Department Most common Emergency Department
diagnosis in patients 50 years or olderdiagnosis in patients 50 years or older Over 50% will not be diagnosed with coronary Over 50% will not be diagnosed with coronary
artery diseaseartery disease The identification of chest pain patients The identification of chest pain patients
with significant coronary artery disease with significant coronary artery disease remains a challengeremains a challenge
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StrategiesStrategies
One strategy is the use of chest pain One strategy is the use of chest pain observation units (OU) in the EDobservation units (OU) in the ED
EDs have developed OUs to efficiently and EDs have developed OUs to efficiently and safely manage low risk chest pain patients safely manage low risk chest pain patients with serial cardiac enzymes and subsequent with serial cardiac enzymes and subsequent cardiac stress testingcardiac stress testing
There is still a significant cost and time There is still a significant cost and time investment involvedinvestment involved
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Current Management of Current Management of Low-Risk Chest Pain in Low-Risk Chest Pain in
the EDthe ED 54 year old male complains of chest 54 year old male complains of chest
painpain Patient smokes & has high blood Patient smokes & has high blood
pressurepressure ED courseED course
Near normal ECGNear normal ECG First cardiac enzymes are within normalFirst cardiac enzymes are within normal He is now chest pain freeHe is now chest pain free
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Current StrategyCurrent Strategy
7.7% of missed myocardial 7.7% of missed myocardial infarctions dieinfarctions die You cannot send this patient homeYou cannot send this patient home
Admit to the observation unitAdmit to the observation unit Continuous telemetry monitoringContinuous telemetry monitoring Serial cardiac enzymesSerial cardiac enzymes Either a stress echo or stress ECGEither a stress echo or stress ECG
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New Potential New Potential ManagementManagement
64-slice multidetector computed 64-slice multidetector computed tomography of the coronary arteries tomography of the coronary arteries (MDCT) - new modality for evaluation of (MDCT) - new modality for evaluation of CADCAD
Some advocate use of MDCT in the ED for Some advocate use of MDCT in the ED for low risk chest pain patients as an alternative low risk chest pain patients as an alternative to Observation Unit and stress testing.to Observation Unit and stress testing.
Not current standard of care in the ED Not current standard of care in the ED settingsetting
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RationaleRationale
MDCT may become a first-line screening MDCT may become a first-line screening instrument for detecting significant CAD in instrument for detecting significant CAD in low risk patients presenting to the ED with low risk patients presenting to the ED with chest painchest pain
It is unclear whether the increased cost of It is unclear whether the increased cost of the MDCT test is associated with better the MDCT test is associated with better patient outcomespatient outcomes
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ObjectiveObjective
To estimate the cost-effectiveness of To estimate the cost-effectiveness of MDCT in the ED compared to the current MDCT in the ED compared to the current standard of care for the evaluation of low standard of care for the evaluation of low risk chest pain patients presenting to the EDrisk chest pain patients presenting to the ED
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Study DesignStudy Design
Decision analytic model Decision analytic model Compare the health outcomes and costs that Compare the health outcomes and costs that
result from different risk-stratification result from different risk-stratification strategies for ED patients with low risk strategies for ED patients with low risk chest painchest pain
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PopulationPopulation
54 year old male, low risk chest 54 year old male, low risk chest painpain Reflects the average age and most prevalent Reflects the average age and most prevalent
gendergender 3 Scenarios3 Scenarios
1) OU care followed by stress ECG testing1) OU care followed by stress ECG testing 2) OU care followed by stress 2) OU care followed by stress
echocardiographyechocardiography 3) No OU care, MDCT done in ED3) No OU care, MDCT done in ED
Probability of Missed CAD-Death, % 7.7 2-75 Probability of Missed CAD- MI, % 44 10-75 Probability of Missed CAD- Health, % 49 10-75 Probability of Death after Angio, CAD Pos, % 0.1 .05-.5 Probability of Death after Angio, CAD Neg, % 0.02 .018-.02 Probability CABG, % 10 1-50 Probability of Med Management, % 10 1-50 Probability of PCI, % 80 50-99 Probability of CABG and Death, % 3.0 1-10 Probability of CABG and MI, % 3.3 1-10 Probability of Med Management and Death, % 2 1-5 Probability of Med Management and MI, % 2 1-5 Probability of Death after PCI, % 2.5 1-10 Probability of MI after PCI, % 8.5 1-50 Probability of Indeterminate MDCT 3.8 0-30
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Inputted Parameter Base Case
Analysis
Range Used in Sensitivity Analysis
Cost MDCT, $ 1500 $750-$3000 Stress Echocardiography, $ 277 $188-$750 Stress ECG, $ 105 $78-$312 Angiography, $ 2278 $1282-$5126 PCI, $ 12228 $8273-$33092 CABG, $ 35723 $23240-$92958 OU Physician and Hospital, $ 1712 $856-$3424 Missed CAD and Death 58745 $29373-$117490 Missed CAD and MI 15549 $7776-$31098
Utility Alive-Health 1 Alive-MI 0.88 0.5-0.95 Death 0
Life Expectancy Life Expectancy after Health, yrs 24.77 Life Expectancy after MI, yrs 11.2
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Healthcare CostsHealthcare Costs
All costs were adjusted to 2007 U.S. dollars All costs were adjusted to 2007 U.S. dollars using the Medical Care component of the using the Medical Care component of the Consumer Price Index. Consumer Price Index.
No discounting was necessary as costs and No discounting was necessary as costs and cost-effectiveness were examined for a 30-cost-effectiveness were examined for a 30-day period after adjustment to 2007 dollars.day period after adjustment to 2007 dollars.
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Sensitivity AnalysisSensitivity Analysis
Test robustness of the results to changes in Test robustness of the results to changes in model assumptions and estimates model assumptions and estimates
Threshold sensitivity analysis Threshold sensitivity analysis To determine at which point these input To determine at which point these input
parameters resulted in a substantial impact on parameters resulted in a substantial impact on cost, effectiveness, or cost-effectiveness of each cost, effectiveness, or cost-effectiveness of each modalitymodality
Conducted a Monte Carlo analysis to evaluate Conducted a Monte Carlo analysis to evaluate uncertainty by varying all of the input model uncertainty by varying all of the input model variables simultaneously to assess the overall variables simultaneously to assess the overall variability of the modelvariability of the model Each scenario was simulated 10,000 times using Monte Each scenario was simulated 10,000 times using Monte
Carlo simulationCarlo simulation This method accounts for variability among This method accounts for variability among
individuals and tests, which more closely individuals and tests, which more closely resembles reality. The 95% confidence intervals resembles reality. The 95% confidence intervals of the ICERs were determined of the ICERs were determined
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ResultsResults
ICERs ICERs ICERs
Stress ECG Stress Echo MDCT Echo vs. ECG (95%CI)
MDCT vs. ECG (95%CI)
MDCT vs. Echo (95%CI)
Low Risk (Base Case)
Dominant (Dominant-$123,467/QALY)
Dominant (Dominant-$7,332/QALY)
Dominant (Dominant-$29,738/QALY)
Base Case 6% CAD
Cost $3,461 $3,265 $2,684
QALYs 24.59 24.63 24.69
Dominant: Less Costly, More Effective
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Sensitivity AnalysisSensitivity Analysis
MDCT remained dominant to the other strategies MDCT remained dominant to the other strategies because it had better outcomes and lower costsbecause it had better outcomes and lower costs
Five input parameters that resulted in the MDCT Five input parameters that resulted in the MDCT having higher costs than OU + Stress Echohaving higher costs than OU + Stress Echo cost of MDCT > $2,097 cost of MDCT > $2,097 Base case ($1500)Base case ($1500) cost of OU care < $1,092 cost of OU care < $1,092 Base case ($1712)Base case ($1712) prevalence of CAD > 70% prevalence of CAD > 70% Base case (6%) Base case (6%) specificity MDCT < 65% specificity MDCT < 65% Base case (84%) Base case (84%) indeterminate rate MDCT > 30% indeterminate rate MDCT > 30% (3.8%) (3.8%)
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LimitationsLimitations Our analysis relies heavily on published assessmentsOur analysis relies heavily on published assessments We use sensitivity and specificity of the MDCT from We use sensitivity and specificity of the MDCT from
of studies with a CAD prevalence of 64%.of studies with a CAD prevalence of 64%. All input parameters taken from the literature may be over- All input parameters taken from the literature may be over-
or understated in this low risk OU populationor understated in this low risk OU population Radiation from a 64-slice scanner evaluating the Radiation from a 64-slice scanner evaluating the
coronary arteries has a lifetime risk of cancer coronary arteries has a lifetime risk of cancer Patients who have significant CAD on MDCT do need Patients who have significant CAD on MDCT do need
to get another catheterization. to get another catheterization. This requires another dye load, renal pathology is not This requires another dye load, renal pathology is not
modeledmodeled
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ConclusionsConclusions MDCT strategy is less costly and more MDCT strategy is less costly and more
effective than both OU based strategies in effective than both OU based strategies in chest pain patients presenting to the ED chest pain patients presenting to the ED
Largely due to the diagnostic test Largely due to the diagnostic test performance of MDCT and the avoidance performance of MDCT and the avoidance of OU costsof OU costs
