Support grants: grant number 5 UL1 RR024982-03; principal investigator Packer, Milton; project title North and Central Texas Clinical and Translational Science Initiative (UL1);award dates 9/17/07–5/31/12. KL2 Grant Information (replaces the K12):grant number 5 KL2 RR024983-03;principal investigator Packer, Milton; project title North and Central Texas Clinical and Translational Science Initiative (KL2);award dates 09/17/07–5/31/12. Information on NCRR is available at http://www.ncrr.nih.gov/. Information on Re-engineering the Clinical Research Enterprise can be obtained from http://nihroadmap.nih.gov/clinicalresearch/overview-translational.asp. These support grants did not influence the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
Is Coronary Computed Tomography Angiography a Resource Sparing Strategy in the Risk Stratification and Evaluation of Acute Chest Pain? Results of a Randomized Controlled Trial
Article first published online: 13 MAY 2011
© 2011 by the Society for Academic Emergency Medicine
Academic Emergency Medicine
Volume 18, Issue 5, pages 458–467, May 2011
How to Cite
Miller, A. H., Pepe, P. E., Peshock, R., Bhore, R., Yancy, C. C., Xuan, L., Miller, M. M., Huet, G. R., Trimmer, C., Davis, R., Chason, R. and Kashner, M. T. (2011), Is Coronary Computed Tomography Angiography a Resource Sparing Strategy in the Risk Stratification and Evaluation of Acute Chest Pain? Results of a Randomized Controlled Trial. Academic Emergency Medicine, 18: 458–467. doi: 10.1111/j.1553-2712.2011.01066.x
UTSWMC IRB #032007-067.
Supervising Editor: Stephen W. Smith, MD.
- Issue published online: 13 MAY 2011
- Article first published online: 13 MAY 2011
- Received July 16, 2010; revisions received September 27, October 4, October 8, and October 16, 2010; accepted October 18, 2010.
ACADEMIC EMERGENCY MEDICINE 2011; 18:458–467 © 2011 by the Society for Academic Emergency Medicine
Objectives: Annually, almost 6 million U.S. citizens are evaluated for acute chest pain syndromes (ACPSs), and billions of dollars in resources are utilized. A large part of the resource utilization results from precautionary hospitalizations that occur because care providers are unable to exclude the presence of coronary artery disease (CAD) as the underlying cause of ACPSs. The purpose of this study was to examine whether the addition of coronary computerized tomography angiography (CCTA) to the concurrent standard care (SC) during an index emergency department (ED) visit could lower resource utilization when evaluating for the presence of CAD.
Methods: Sixty participants were assigned randomly to SC or SC + CCTA groups. Participants were interviewed at the index ED visit and at 90 days. Data collected included demographics, perceptions of the value of accessing health care, and clinical outcomes. Resource utilization included services received from both the primary in-network and the primary out-of-network providers. The prospectively defined primary endpoint was the total amount of resources utilized over a 90-day follow-up period when adding CCTA to the SC risk stratification in ACPSs.
Results: The mean (± standard deviation [SD]) for total resources utilized at 90 days for in-network plus out-of-network services was less for the participants in the SC + CCTA group ($10,134; SD ±$14,239) versus the SC-only group ($16,579; SD ±$19,148; p = 0.144), as was the median for the SC + CCTA ($4,288) versus SC only ($12,148; p = 0.652; median difference = –$1,291; 95% confidence interval [CI] = –$12,219 to $1,100; p = 0.652). Among the 60 total study patients, only 19 had an established diagnosis of CAD at 90 days. However, 18 (95%) of these diagnosed participants were in the SC + CCTA group. In addition, there were fewer hospital readmissions in the SC + CCTA group (6 of 30 [20%] vs. 16 of 30 [53%]; difference in proportions = –33%; 95% CI = –56% to –10%; p = 0.007).
Conclusions: Adding CCTA to the current ED risk stratification of ACPSs resulted in no difference in the quantity of resources utilized, but an increased diagnosis of CAD, and significantly less recidivism and rehospitalization over a 90-day follow-up period.
Each year, approximately 6 million U.S. citizens are evaluated for acute chest pain syndromes (ACPSs) and billions of dollars of resources are utilized.1,2 While a large part of this cost is attributable to the expense of hospitalization at the time of index evaluation, 60% of those hospitalized are determined not to have coronary artery disease (CAD) as the underlying factor.3–5 Patients are generally hospitalized for continued evaluation and monitored observation because providers may not feel comfortable in excluding CAD or a myocardial infarction (MI) with the current technologies available to them. As such, the inability to rapidly diagnose MI or underlying CAD as the cause of ACPSs has serious public health and economic consequences. Moreover, considering a reported rate of 2% to 8% for unrecognized acute MI, the risk of malpractice litigation further augments the rate of hospitalization and its associated resource utilization.6
The current emergency department (ED) standard care (SC) for risk stratification of ACPS patients in many institutions includes clinical data, serial electrocardiograms (ECGs), and cardiac biomarkers1,7–9 (Figure 1). The addition of exercise stress testing and echocardiograms to this regimen has been studied, but due to the suboptimal sensitivity of exercise stress testing,10–13 and the significant cost of adding nuclear perfusion studies, neither of these technologies have been adopted routinely in many institutions.11,12 Consequently, the current process for excluding CAD has remained time-consuming and relatively expensive.6,7,14–23
In 2009, researchers demonstrated that coronary computerized tomography angiogram (CCTA) technology (Figure 2) is safe and also quite feasible to perform in the ED chest pain population.12,24,25 Furthermore, computer simulation models including CCTA in chest pain patient evaluation demonstrated a marginal association with improved quality-adjusted longevity, raised cost-effectiveness ratios, and illustrated the need for controlled trials to be executed to guide policy.26,27
To date, there have been no published randomized controlled clinical trials addressing the primary aim of quantifying the resource utilization of adding CCTA to the current SC in the ED evaluation of ACPS patients. We posited that adding a CCTA to the SC (SC + CCTA) in patients with low- to intermediate-risk ACPS would be associated with lower total resource utilization in the 90-day follow-up period after the index ED visit. Accordingly we performed a prospective randomized controlled trial examining the resource utilization with and without the addition of CCTA to the risk stratification of ACPS patients presenting to the ED.
This was a prospective randomized controlled trial, conducted between October 20, 2008, and February 28, 2009. Institutional review board approval was obtained at both the University of Texas Southwestern Medical Center (the affiliated medical school) and the Parkland Hospital Healthcare System (the primary study site). All participants provided written informed consent.
Study Setting and Population
The trial was conducted at a single health care facility in Dallas, Texas. The ED, based at the public county hospital, serves over 100,000 adult patients per year.
Patients at least 35 years of age who were evaluated for ACPS in an urban ED (Figure 3) were eligible for inclusion. Patients were screened Monday through Friday between 7 am and 4 pm by the clinical trial nurse and/or the primary investigator. Of 72 eligible patients, 60 granted their consent and were assigned randomly in a 1:1 ratio using an “open-label” fashion. There were five blocks, with 12 participants per block. CT scanners were immediately available and an expert reader was available within 2 hours of CCTA completion.
Eligibility criteria included patients who: 1) complained of chest pain compatible with possible ischemia during the previous 12 hours; 2) were predicted to be of low to intermediate risk of MI and/or complications according to established criteria;1,7–10,14 3) had normal or indeterminate ECG findings; 4) had negative cardiac biomarkers, including those for creatine kinase-MB, myoglobin, and/or cardiac troponin I at initial testing; 5) were deemed by the treating emergency physician to require admission to the hospital at the time of risk stratification; 6) required cardiology consultation in the ED; 7) were at least 35 years of age; 8) were able to hold their breath for at least 15 seconds (which is required in CCTA imaging to obtain a quality static anatomical image); and 9) had an initial heart rate of <70 beats/min or <70 per beats/min after the administration of beta-blocker medication. Excluded patients included those who: 1) had a contraindication to iodinated and/ or beta-blocking drugs; 2) had compromised renal function defined as creatinine of ≥1.2 mg/dL; 3) were pregnant or suspected to be pregnant; 4) were a member of a vulnerable population (e.g., incarcerated patients); 5) had documented CAD (by prior invasive coronary angiography, CCTA detection, documented placement of coronary artery stents, prior angioplasty, or prior coronary artery bypass grafts); 6) had prior cardiac imaging (within the past year) that excluded CAD, including invasive coronary angiography, CCTA, or nuclear stress testing; 7) were unstable clinically (e.g., abnormal vital signs, altered mental status); 8) had an ECG finding that was diagnostic of ischemia or MI (significant Q-waves, ST-segment deviations of >0.5 mm, or T-wave inversions); 9) were in atrial fibrillation or had a markedly irregular rhythm; 10) had contrast administration within the previous 24 hours; 11) were unable to be provided with an 18-gauge antecubital intravenous (IV) access; or 12) had a medical care home out-of-network (to control for the follow-up care).
In the ED, each of the 60 participants received standard treatment. This included standard 12-lead ECG tracings; coronary biomarkers (troponin I) obtained at 0, 4, and 9 hours after ED arrival; and continuous ECG monitoring. All enrolled participants received aspirin (81 mg orally), sublingual nitroglycerin (0.4 mg) for the chest pain until it was alleviated (up to three administrations, about 5 minutes apart), cardiology consultation, and additional cardiac testing as required.
Participants assigned to the SC + CCTA group had the test performed according to previously published methods.28 Briefly, participants requiring beta-blocking drugs were administered metoprolol 5 to 30 mg IV to achieve a heart rate of <70 beats/min. A Toshiba 64-slice multidetector CT scanner was used (Toshiba America Medical Systems, Inc., Tustin, CA). A nonenhanced ECG-gated scan was acquired for a coronary artery calcium (CAC) score followed by a contrast-enhanced scan with 60 to 100 mL of contrast injected through an antecubital vein at 5 mL per second. This infusion was followed by 20 mL injected at 3 mL per second followed by a 40-mL saline flush. Scans were transferred into a 3D workstation (Vitrea, Toshiba) for analysis. The Agatston and Volume CAC scores were reported using standard analysis software (Vitrea 2, Vital Images, Inc., Minnetonka, MN).
A board-certified cardiologist with Level 2 CCTA image training performed the initial CCTA image interpretation and reported it as normal, nonobstructive, or obstructive CAD as previously described in the cardiology literatue.25,28–32 Independently, the lead attending physician on the cardiology team (not involved in the study) evaluating the participant in the ED interpreted the CCTA images, reviewed the initial interpretation by the image specialist, and decided on the most appropriate disposition of the patient. The final CCTA interpretations determined by the two independent readers are reflected in the study results. A clinical decision algorithm for further testing and treatment of participants receiving the CCTA is depicted in Figure 4.
The primary outcome was the sum of all resources utilized for both in-network and out-of-network health care services provided over a 90 day follow-up period after the index ED visit, including ED care, cardiology clinics, primary care and dental clinics, and in-hospital care. Recognizing from existing literature of cost analyses that resource utilization data are not normally distributed,33–35 both nonparametric and parametric descriptive analyses were employed, including both medians and means for the primary outcome. Resources utilized and clinical outcome data from in-network providers were obtained from the electronic medical record, information management system (EPIC, Verona, WI), and Cardiovascular Information Management System (CIMS, Philips Electronics, North American Corp., Andover, MA) within the primary network (the hospital and medical school facilities and their affiliated clinics). Use of resources from out-of-network (other health care facility) providers were predicted using the utilization and cost-chest pain (UAC-CP) participant self-reporting inventory, derived from the utilization and cost methodology33–37 because they were not observable.
Comparing in-network provider records and reasonable charges with the UAC-CP inventory enabled us to calibrate responses to minimize underreporting biases and to compute unit costs of care for out-of-network providers from comparable in-network charge schedules. The UAC-CP is a clinical interview data tool applied in psychiatric research38,39 that counts patient use of care (visits, encounters, testing, days) by setting (outpatient, ED, and inpatient care), service type, and provider. Additional data collected included factors that predict patient use of care classified into predisposition-to-care factors (ethnicity, sex, and the Patients’ Perception of Benefits inventory36,37), enabling factors (income), and need factors (the self-reported Short Form 12 version 2 [SF-12v2]).40,41 All participants were surveyed at the time of the index ED visit and at 90 days via phone interviews.
All resources utilized were computed for inpatient care at a per diem diagnosis-related group (DRG) code42 and for outpatient care as a total of current procedural terminology.43 These costs were priced at the nationally published 75th percentile charge schedule in 2009 U.S. dollars.44 The 75th percentile was chosen for the analysis because the actual CCTA in-network cost was consistent with this percentile. This choice allowed us to maintain parity between the resources utilized for the CCTA ($1,100) and those used for all other services including ECG ($93); emergency care ($310); hospitalization, DRG280 ($9,281) and DRG313 ($4,038); echocardiogram ($619); coronary catheterization ($8554); exercise stress test ($437); nuclear perfusion test ($967); stress echocardiogram ($1,119); transesophageal echocardiogram ($650); and outpatient physician visit ($225).
For participants who were lost to follow-up or who died, all costs were censored at the time of the last follow-up, and that last observation of cumulative resources utilized was carried forward to the 90-day endpoint. To address missing data, a multiple imputation approach to determine the unit cost at 90-day UAC-CP follow-up data was employed.33–35
Sample size estimates and power were based on the cost of the CCTA with the assumption that all other SC services would be the same in both groups. The cumulative mean cost for traditional risk stratification based on 54 historical cases was $3,984.81 (standard deviation [SD] ±$1,487.09). Assuming a difference in total mean cost of $1,100 between the two groups, a total sample size of 60 patients (30 per group) provided at least 80% power to detect a statistically significant difference over a 90-day follow-up at a 0.05 two-sided level of significance.
To compute the calibrated total resource utilization of out-of-network services for each participant at 90 days after the index ED visit, regression models with polynomial expansion using the self-reported UAC-CP utilization of service data and unit resource utilization per service were performed. The main outcome of total resources utilized, including in-network plus out-of-network services at 90 days, was then calculated by adding the actual resource utilization of in-network services and the calibrated total resource utilization of out-of-network services. The distributions of the final total of resources utilized for the two randomized groups (SC + CCTA vs. SC only) were compared using the nonparametric Wilcoxon rank sum test and median and mean differences in resources utilized were computed using the Hodges-Lehmann method.45,46
For secondary outcomes, differences in proportions were examined using chi-square tests and differences in means or medians were examined using a parametric two-sample t-test or nonparametric Wilcoxon rank sum test, respectively. SF-12v Health Survey was interpreted based on the adopted norm-based scoring method for the SF-12v Health Survey scales and summary measures for two health domains (physical and mental).38,39
Statistical analyses were performed using SPSS version 16 (SPSS, Inc., Chicago, IL) and SAS version 9.2 (SAS Institute, Cary, NC). p-values less than two-sided 0.05-α levels are considered statistically significant.
The mean age of all 60 participants was 51 years (SD ± 10 years; range = 35 to 76 years). Of the 60 participants, 30 (50%) were male, 28 (47%) were African American, 11 (18%) were white, and 20 (33%) were Hispanic; 36 (66%) had an annual household income that was less than $10,000 (Table 1).
|Variable||SC + CCTA (n = 30)||SC (n = 30)||Total (N = 60)|
|Male||13 (43%)||17 (57%)||30 (50%)|
|Female||17 (57%)||13 (43%)||30 (50%)|
|Mean||51 ± 10||51 ± 10||51 ± 10|
|African American||14 (47%)||14 (47%)||28 (47%)|
|Asian||0 (0%)||1 (2%)||1 (2%)|
|White||7 (23%)||4 (13%)||11 (18%)|
|Hispanic||9 (30%)||11 (37%)||20 (33%)|
|Household income ($)|
|<10||15 (58%)||21 (72%)||36 (66%)|
|<25||7 (27%)||4 (14%)||11 (18%)|
|<50||3 (11%)||1 (4%)||4 (7%)|
|<100||1 (4%)||0 (0%)||1 (2%)|
|>100||0 (0%)||3 (10%)||3 (6%)|
A total of 685 patients with ACPSs ranging from those with very low likelihood atypical chest pain presentations (e.g., costochondral point tenderness) to high-risk patients (e.g., those manifesting a classic ST-elevation MI or arrhythmias or those with unstable hemodynamics) were screened for enrollment criteria. After identifying the applicable target population (finite low- to intermediate-risk patients), 72 met criteria. Of these appropriate candidates, 12 refused to participate after reviewing the consent documents. The remaining 60 patients granted consent and were assigned to the SC or SC + CCTA groups according to the randomization process (Figure 3). Of the 30 participants in the SC + CCTA group, two did not have results from the CCTA test, including one who became confused prior to having the CCTA performed and the second who did not complete the CCTA due to body habitus. The first participant later completed an exercise stress test that was interpreted as being indeterminate for CAD. Both participants were included in the intention-to-treat analysis. None of the SC group patients received a CCTA during the 90-day study period.
In terms of the main study endpoint (Table 2), the mean for total resources utilized at 90 days (including in-network and out-of-network resource utilization) was less for the participants in the SC + CCTA group ($10,134; SD ±$14,239) versus the SC-only group ($16,579; SD ±$19,148; p = 0.144) as was the median for the SC + CCTA ($4,288) versus SC only ($12,148; p = 0.652). The median difference in total resources utilized was –$1,291 (95% confidence interval [CI] = –$12,219 to $1,100). Likewise, the total mean calculation for only in-network resources utilized for the SC + CCTA group was significant at $7,593 (SD ±$11,590) versus $15,697 (SD ±$18,753; p = 0.049) for the SC-only group. The largest driver of resource utilization difference was due to the increased rate of being admitted or readmitted to the hospital among the SC-only group participants. The total mean and median sums for resources utilized in the SC + CCTA group versus the SC-only group for out-of-network services were not significantly different (Table 2).
|Variable||SC + CCTA (n = 30)||SC (n = 30)||p-value*|
|In-network and out-of-network services (users only)|
|Mean ± SD||$10,134 ± $14,239||$ 16,579 ± $19,148||0.144|
|Median difference in total cost favoring CCTA (95% CI) –$1,291 (–$12,219, $1,100)†|
|In-network services only (users only)|
|Mean ± sd||$7,593 ± 11,590||$15,697 ± $18,753||0.049|
|Out-of-network services only (users only)|
|Mean ± SD||$2,541 ± $9,714||$881 ± $1,494||0.359|
|Total cost of individual in-network services ($)|
|Mean ± sd||$413 ± $349||$651 ± $851||0.162|
|Mean ± SD||$1,791 ± $3,610||$1,914 ± $3,132||0.889|
|Other medical providers (primary care, dental, etc.)|
|Mean ± sd||$293 ± $401||$473 ± $428||0.098|
|Mean ± SD||$3,996 ± $10,160||$12,660 ± $17,105||0.02|
Secondary endpoints (Table 3) demonstrated that in the SC + CCTA group, 28 of 30 (93%) had a formal diagnosis of the presence or absence of CAD made at 90 days compared to only 6 of 30 (20%) with formal diagnosis (of CAD or not) and 24 of 30 (80%) with no formal diagnosis (p < 0.001) in the SC group. When excluding the two participants in the SC + CCTA group who did not receive the CCTA, all 28 persons in the SC + CCTA group had a formal diagnosis at the 90-day mark. Among the 60 study participants, only 19 had an established diagnosis of CAD at 90 days. However, 18 of 28 (64%) of these diagnosed participants were in the SC + CCTA group compared to one of six (17%) in the SC-only group (p = 0.032). The remaining participants with diagnosis at 90-day follow-up, including 10 of the 28 (36%) in the SC + CCTA group and five of six (83%) in the SC-only group, were determined to not have CAD. In the SC + CCTA group, four of 18 participants underwent subsequent coronary catheterization and one was found not to have CAD. Two of the four were found to have obstructive CAD; one of the two had a stent placed. In the SC-only group, four of the 30 (13%) participants underwent coronary catheterization. One of the four (25%) had nonobstructive CAD, and three of the four (75%) were determined to be free of CAD (Table 3). Furthermore, in the SC + CCTA group, six of 30 (20%) participants were admitted or readmitted to the hospital versus 16 of the 30 (53%) in the SC-only group at 90 days (difference in proportions = –33%; 95% CI = –56% to –10%; p = 0.007). The UAC-CP inventory of Perception of Benefit resulted in no significant difference on index visit data between-group means (SC = 11.04, SC + CCTA = 8.54; p = 0.31); at 90-day follow-up data between-group means (SC = 11.64, SC + CCTA = 12.88; p = 0.60); and between groups difference, index visit versus 90-day means (SC = 2.58, SC + CCTA = 4.76; p = 0.49). There was not a significant difference when comparing the SC + CCTA group index ED visit mean score (8.54) with the 90-day mean score of 12.88 (increasing value = negative Perception of Benefit). The SF-12v2 health outcome questionnaire resulted in no significant difference in change from baseline to 90-day data between groups means for the Physical Component Summary SC + CCTA = 1.0 (SD ± 7.4) and SC = –2.3 (SD ± 13.4); p = 0.32; and the Mental Component Summary SC + CCTA = –0.5 (SD ± 11.5) and SC = –0.7 (SD ± 11.9; p = 0.95). These 90-day follow-up data for both the UAC-CP and SF-12v2 were obtained in 15 of 30 (50%) of the SC + CCTA group and 17 of 30 (57%) of the SC-only group.
|Variable||CTA + SC (n = 30)||SC (n = 30)||p-value|
|No diagnosis made at 90-day follow-up||2 (7)||24 (80)||<0.001|
|Diagnoses made at 90-day follow-up||28 (93)||6 (20)|
|CAD present||18/28 (64)||1/6 (17)||0.032|
|CAD not present||10/28 (36)||5/6 (83)|
|Specific additional testing* and procedures|
|Echo (TTE)||2 (7)||5 (17)||0.424†|
|Stress echocardiography||3 (10)||1 (3)||0.612†|
|Exercise stress test||2 (7)||6 (20)||0.254†|
|Nuclear perfusion||3 (10)||6 (20)||0.472†|
|TEE||0 (0)||0 (0)||0.278|
|Coronary catheterization||4 (13)||4 (13)||1.000†|
|Stents||1 (3)||0 (0)||1.000†|
|Number of return visits to|
|≥ 1||5 (17)||10 (33)||0.136|
|None||25 (83)||20 (67)|
|Mean ± sd||2.0 ± 2.2||3.3 ± 4.0||0.518|
|Median (min-max)||1.0 (1.0–6.0)||1.5 (1.0–13.0)||0.369|
|≥ 1||3 (10)||5 (17)||0.706†|
|None||27 (90)||25 (83)|
|Mean ± SD||1.0 ± 0.0||1.2 ± 0.4||0.482|
|Median (range)||1.0 (1.0–1.0)||1.0 (1.0–2.0)||0.606|
|≥ 1||15 (50)||21 (70)||0.114|
|None||15 (50)||9 (30)|
|Mean ± sd||2.6 ± 1.7||3.0 ± 1.5||0.471|
|Median (range)||3.0 (1.0–6.0)||3.0 (1.0–6.0)||0.428|
|Number of participants hospitalized at least once during 90-day follow-up (admitted/readmitted)||6 (20)||16 (53)||0.007|
|Number of hospital days|
|Mean ± SD||3.0 ± 3.1||3.7 ± 3.9||0.704|
|Median (range)||2.0 (1.0–9.0)||2.5 (1.0–17.0)||0.472|
This trial, evaluating the relative use of resources when adding CCTA to evaluation of low- to intermediate-risk ACPS patients, builds upon the work reported by Karlsberg et al.47 who reported a reduction in the need for further testing over a 6-month period when incorporating CCTA in their outpatient cardiology clinic. Using prospectively specified parameters and a 3-month follow-up period, the results of this trial indicate a relative improvement in both resource utilization and earlier diagnosis. Although based on the numbers studied, the total median resource utilization difference in the SC + CCTA group compared to the SC-only group was not statistically significant, there was, for example, nearly a threefold difference in the median values for total resources utilized in the SC + CCTA group ($4,288) versus the SC-only group ($12,148) indicating a clear trend in favor of adding the CCTA to the SC. Furthermore, when just examining secondary results such as in-network utilization, the rates of hospital admissions and readmissions were significant.
It could be argued that, despite well-delineated guidelines, if CCTA becomes part of the routine ED risk-stratification regimen of ACPS patients, the consequences may be additional utilization of CCTA in a broader range of ACPS patients. In turn, this may gradually result in a larger number of persons with additional radiation exposure and a growing chance for possible renal injury. However, this trial demonstrates that only about 11% of all types of patients screened for “chest pain” had a CCTA performed using applicable inclusion criteria. In fact, those patients most likely to be at risk for compromised renal function, allergies to dye, or heart rate elevations would not have been eligible for CCTA as part of the screening process. The study also revealed that in contrast to the current SC approach, one will find a much higher probability of having a definitive diagnosis (either positive or negative for CAD) by 90 days. In turn, the need for nuclear imaging and other testing (with their own finite risks) could be avoided and patients would have less recidivism. In the case of positive tests, lifestyle and medical interventions can begin more rapidly, and days lost for additional testing, hospitalizations, and follow-up diagnostic visits can be obviated. Specifically, adding the CCTA to SC resulted in a diagnosis (positive or negative for CAD) for 28 of the 30 (93%) participants. Excluding the two participants who did not receive their CCTA for technical reasons (mental status and body size), it is clear that the addition of this tool provided very specific information for the remaining 28 patients.
Furthermore, among those 28 patients, CAD (as defined in this study) was found in 18 patients (64%) at 90 days. Compared to the existing literature48 using SC diagnostic procedures, this finding was relatively high for those with low- to intermediate-risk ACPSs, which perhaps could indicate either a more sensitive test or risk stratification process. This may reflect our local patient population, their demographics, or their inclinations to come to the ED and be evaluated. However, the data from the perception of benefit and health outcome surveys revealed no differences in the study groups or even pessimism about accessing care. More importantly, early recognition of CAD can potentially result in improved outcomes. The SC-only group better reflected the existing literature. Specifically, only six of the 30 SC-only participants (20%) had a diagnosis (positive or negative for CAD) by 90 days, and the presence of CAD was found in only one of those six participants. This scenario resulted in a trend for additional subsequent testing in 17 (57%) of the 30 SC-only participants (p = 0.121), as well as more ED utilization (10 of 30; p = 0.136), cardiology consultation (5 of 30; p = 0.706), other follow-up visits (21 of 30; p = 0.112), and hospitalizations (16 of 30; p = 0.007) by 90-days. Increased hospitalization resource utilization may have occurred in the SC-only group for several reasons. As shown in previous studies, when the physician explains to the participants that their coronary arteries were observed (via CCTA), compared to stress test and other results (tests that infer knowledge), patients become more confident and satisfied; thus they return less often for evaluation.48 Additionally, when participants returned for evaluation, the CCTA information enables physicians to send the participant home without further workup.30 Conversely, for participants not receiving the CCTA, the use of hospitalization resources was subsequently increased.
While these trends for differences could be validated in a larger sample size (enrollment was restricted due to the funding limitations for a pilot study), the one major significant difference (in hospitalizations) provides strong support for both the resource sparing effect and the early diagnostic value of adding CCTA to the initial ED protocol. More specifically, many of the SC group participants did not follow-up for further testing (43%), even though a significantly greater number of participants were admitted or readmitted to the hospital.
If CCTA is to be accepted, team member communication, including the emergency physician, the cardiologist, and the image interpreter must be clear and timely. For example, the breakdown of these communications resulted in the unnecessary coronary catheterization of one participant in the trial.
Despite the very useful findings of the study, there were several design limitations. In our current methodology, participants knew that they had been assigned to the CCTA group, and thus blinding was not possible. This might add bias to subsequent surveys and behaviors, although the study results did not indicate that this was a true issue. One consideration for future studies would be the use of a sham CCTA intervention for the control group.
Another issue is that underreporting biases exist when survey tools are employed to capture patient use of out-of-network service providers. Nevertheless, we minimized this by using all available data including provider records and patient self-reports that were calibrated. Also, the 90-day follow-up of UAC-CP and SF-12v2 were 15 of 30 (50%) in SC + CCTA group and 17 of 30 (57%) in SC-only group. We believe that we helped to mitigate this by calibrating these self-reported data using a multiple imputation approach to determine the unit cost.
We were unable to show a difference in the 90-day total resource utilization when including coronary computerized tomography angiography in the risk stratification of low- to intermediate-risk acute chest pain syndrome patients compared to standard care alone, but we did note an increased diagnosis of coronary artery disease and significantly less recidivism and rehospitalization over a 90-day follow-up period.
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