Clinical implications of referral bias in the diagnostic performance of exercise testing for coronary artery disease

Real-world evaluation of an algorithmic machine-learning-guided testing approach in stable chest pain: a multinational, multicohort study

Aims

An algorithmic strategy for anatomical vs. functional testing in suspected coronary artery disease (CAD) (Anatomical vs. Stress teSting decIsion Support Tool; ASSIST) is associated with better outcomes than random selection. However, in the real world, this decision is rarely random. We explored the agreement between a provider-driven vs. simulated algorithmic approach to cardiac testing and its association with outcomes across multinational cohorts.

Methods and results

In two cohorts of functional vs. anatomical testing in a US hospital health system [Yale; 2013-2023; n = 130 196 (97.0%) vs. n = 4020 (3.0%), respectively], and the UK Biobank [n = 3320 (85.1%) vs. n = 581 (14.9%), respectively], we examined outcomes stratified by agreement between the real-world and ASSIST-recommended strategies. Younger age, female sex, Black race, and diabetes history were independently associated with lower odds of ASSIST-aligned testing. Over a median of 4.9 (interquartile range [IQR]: 2.4-7.1) and 5.4 (IQR: 2.6-8.8) years, referral to the ASSIST-recommended strategy was associated with a lower risk of acute myocardial infarction or death (hazard ratioadjusted: 0.81, 95% confidence interval [CI] 0.77-0.85, P < 0.001 and 0.74 [95% CI 0.60-0.90], P = 0.003, respectively), an effect that remained significant across years, test types, and risk profiles. In post hoc analyses of anatomical-first testing in the Prospective Multicentre Imaging Study for Evaluation of Chest Pain (PROMISE) trial, alignment with ASSIST was independently associated with a 17% and 30% higher risk of detecting CAD in any vessel or the left main artery/proximal left anterior descending coronary artery, respectively.

Conclusion

In cohorts where historical practices largely favour functional testing, alignment with an algorithmic approach to cardiac testing defined by ASSIST was associated with a lower risk of adverse outcomes. This highlights the potential utility of a data-driven approach in the diagnostic management of CAD.

Goal-directed versus outcome-based financial incentives for smoking cessation among low-income, hospitalised patients: rationale and design of the Financial Incentives for Smoking Treatment II (FIESTA II) randomised controlled trial

INTRODUCTION

Smoking remains the leading preventable cause of death in the USA. Low utilisation of treatments for smoking cessation remains a major barrier for reducing smoking rates. Financial incentives represent an innovative approach to increasing use of therapies for smoking cessation. This paper will describe the rationale and design of the Financial Incentives for Smoking Treatment II (FIESTA II) study, a randomised controlled trial to evaluate the effectiveness and feasibility of goal-directed and outcome-based financial incentives to promote smoking cessation among hospitalised smokers.

METHODS AND ANALYSIS

We are recruiting adult participants who smoked tobacco in the 30 days prior to initial interview and are contemplating quitting smoking. These participants will come from two hospitals in underserved communities in New York City and Los Angeles. They will be randomised into one of three arms. The first arm consists of goal-directed financial incentives plus enhanced usual care, which includes hospital-directed information about quitting smoking, nicotine replacement therapy and referral to a Quitline. The second arm involves outcome-based financial incentives plus enhanced usual care. The third arm consists of enhanced usual care alone. Multiple phone interviews with the participants will be completed after randomisation to assess smoking cessation. Participants will earn $20 for each follow-up interview completed and $30 for each smoking cessation test completed. Those who are randomised to the financial incentive groups can earn an additional $700. The participants in the outcome-based group will receive payments solely for exhibiting cessation, whereas the participants in the goal-based group are also eligible for receiving payments after meeting milestones such as speaking with a helpline coach.

ETHICS

Human research protection committees at New York University School of Medicine and the University of California Los Angeles (UCLA) David Geffen School of Medicine granted ethics approval.Protocol number: IRB#19-000 084.

TRIAL REGISTRATION NUMBER

NCT03979885.

Diagnostic Accuracy Studies in Radiology: How to Recognize and Address Potential Sources of Bias

Accuracy is an important parameter of a diagnostic test. Studies that attempt to determine a test's accuracy can suffer from various forms of bias. As radiology is a diagnostic specialty, many radiologists may design a diagnostic accuracy study or review one to understand how it may apply to their practice. Radiologists also frequently serve as consultants to other physicians regarding the selection of the most appropriate diagnostic exams. In these roles, understanding how to critically appraise the literature is important for all radiologists. The purpose of this review is to provide a framework for evaluating potential sources of study design biases that are found in diagnostic accuracy studies and to explain their impact on sensitivity and specificity estimates. To help the reader understand these biases, we also present examples from the radiology literature.

Coronary stenoses in patients suspected to have obstructive coronary artery disease: the exemption rather than the rule!

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Diagnostic performance of an artificial intelligence-driven cardiac-structured reporting system for myocardial perfusion SPECT imaging

OBJECTIVES

To describe and validate an artificial intelligence (AI)-driven structured reporting system by direct comparison of automatically generated reports to results from actual clinical reports generated by nuclear cardiology experts.

BACKGROUND

Quantitative parameters extracted from myocardial perfusion imaging (MPI) studies are used by our AI reporting system to generate automatically a guideline-compliant structured report (sR).

METHOD

A new nonparametric approach generates distribution functions of rest and stress, perfusion, and thickening, for each of 17 left ventricle segments that are then transformed to certainty factors (CFs) that a segment is hypoperfused, ischemic. These CFs are then input to our set of heuristic rules used to reach diagnostic findings and impressions propagated into a sR referred as an AI-driven structured report (AIsR). The diagnostic accuracy of the AIsR for detecting coronary artery disease (CAD) and ischemia was tested in 1,000 patients who had undergone rest/stress SPECT MPI.

RESULTS

At the high-specificity (SP) level, in a subset of 100 patients, there were no statistical differences in the agreements between the AIsr, and nine experts' impressions of CAD (P = .33) or ischemia (P = .37). This high-SP level also yielded the highest accuracy across global and regional results in the 1,000 patients. These accuracies were statistically significantly better than the other two levels [sensitivity (SN)/SP tradeoff, high SN] across all comparisons.

CONCLUSIONS

This AI reporting system automatically generates a structured natural language report with a diagnostic performance comparable to those of experts.

Apparent Declining Prognostic Value of a Negative Stress Echocardiography Based on Regional Wall Motion Abnormalities in Patients With Normal Resting Left Ventricular Function Due to the Changing Referral Profile of the Population Under Study

Background Cardiology guidelines identify the low-risk response during stress echocardiography as the absence of regional wall motion abnormalities. Methods From 1983 to 2016, we enrolled 5817 patients (age 63±12 years; 2830 males) with suspected coronary artery disease, normal regional, and global left ventricular function at rest and during stress (exercise in 692, dipyridamole in 4291, and dobutamine in 834). Based on timing of enrollment, 4 groups were identified in chronological order of recruitment: years 1983 to 1989, group 1 (n=211); years 1990 to 1999, group 2 (n=1491); years 2000 to 2009, group 3 (n=3285); and years 2010 to 2016, group 4 (n=830). Results There were 240 (4%) events (119 deaths and 121 infarctions) in the follow-up. At 1-year follow-up, the event rate was 0.5% (95% CI, 0.05-0.95), 1.5% (95% CI, -1.18 to 1.82), 1.9% (95% CI, 1.63-2.17), and 1.7% (95% CI, 1.01-2.39; χ², 9.0; P=0.03) in groups 1 to 4, respectively. At multivariable Cox analysis, independent predictors of future events were age (hazard ratio (HR), 1.05; 95% CI, 1.04-1.07; P<0.0001), male sex (HR, 1.57; 95% CI, 1.20-2.04; P=0.001), diabetes mellitus (HR, 1.78; 95% CI, 1.34-2.37; P<0.0001), smoking habit (HR, 1.40; 95% CI, 1.05-1.85; P=0.02), and ongoing anti-ischemic therapy (HR, 1.50; 95% CI, 1.15-1.97; P=0.003) Conclusions Over the past 3 decades, we observed a progressive decline in the prognostic value of a negative test based on regional wall motion abnormalities, likely reflecting both an increase in risk in patients, as well as a potential decrease in test performance due to concomitant anti-ischemic therapy.

The Clinical Utility of a Precision Medicine Blood Test Incorporating Age, Sex, and Gene Expression for Evaluating Women with Stable Symptoms Suggestive of Obstructive Coronary Artery Disease: Analysis from the PRESET Registry

Background: Evaluating women with symptoms suggestive of coronary artery disease (CAD) remains challenging. A blood-based precision medicine test yielding an age/sex/gene expression score (ASGES) has shown clinical validity in the diagnosis of obstructive CAD. We assessed the effect of the ASGES on the management of women with suspected obstructive CAD in a community-based registry.

Materials and Methods: The prospective PRESET (A Registry to Evaluate Patterns of Care Associated with the Use of Corus^® CAD in Real World Clinical Care Settings) Registry (NCT01677156) enrolled 566 patients presenting with symptoms suggestive of stable obstructive CAD from 21 United States primary care practices from 2012 to 2014. Demographics, clinical characteristics, and referrals to cardiology or further functional and/or anatomical cardiac studies after ASGES testing were collected for this subgroup analysis of women from the PRESET Registry. Patients were followed for 1-year post-ASGES testing.

Results: This study cohort included 288 women with a median age 57 years. The median body mass index was 29.2, with hyperlipidemia and hypertension present in 48% and 43% of patients, respectively. Median ASGES was 8.5 (range 1–40), with 218 (76%) patients having low (≤15) ASGES. Clinicians referred 9% (20/218) low ASGES versus 44% (31/70) elevated ASGES women for further cardiac evaluation (odds ratio 0.14, p < 0.0001, adjusted for patient demographics and clinical covariates). Across the score range, higher ASGES were associated with a higher likelihood of posttest cardiac referral. At 1-year follow-up, low ASGES women experienced fewer major adverse cardiac events than elevated ASGES women (1.3% vs. 4.2% respectively, p = 0.16).

Conclusions: Incorporation of ASGES into the diagnostic workup demonstrated clinical utility by helping clinicians identify women less likely to benefit from further cardiac evaluation.

Limited Use of Outpatient Stress Testing in Young Patients With Atypical Chest Pain

Low prevalence of coronary artery disease within this population suggests that younger patients may not require stress testing for chest pain evaluations as long as pretest likelihood is low.

Engaging military couples in marital research: does requesting referrals from service members to recruit their spouses introduce sample bias?

Background

While enrolling dyads in research studies is not uncommon, there is limited literature on the utility of different recruitment strategies and the resulting selection biases. This paper examined two recruitment strategies used to enroll military couples in a longitudinal study, assessing the impact of both strategies on the representativeness of the final study sample.

Method

Descriptive and bivariate analyses were conducted to 1) identify characteristics associated with spouse referral, 2) compare response rates based on recruitment strategy and assess whether recruitment strategy modified correlates of response propensity among spouses, and 3) assess whether referred spouse characteristics differed from non-referred spouses in the final sample. The study sample consisted of married US service members with 2–5 years of military service as of October 2011 and their spouses.

Results

Service members who referred their spouses to participate in the Millennium Cohort Family Study were more likely to be male, have children, serve in the Army, and have combat deployment experience than those who did not refer their spouse. Nearly two-thirds (n = 5331, 64.9%) of referred spouses participated in the Family Study, compared with less than one-third (n = 3458, 29.5%) of directly contacted spouses. Spouse characteristics also differed significantly between recruitment groups.

Conclusions

Overall results suggest that minimal bias was introduced by using a referral recruitment methodology. Service members appeared to be more likely to refer their spouses if they perceived the research topic as relevant to their spouse, such that male service members with combat deployment experience were more likely to refer female spouses caring for multiple children. Referred spouses were significantly more likely to respond to the Millennium Cohort Family Study survey than those who were directly contacted; however, the overall success rate of using a referral strategy was less than recruiting spouses through direct contact. Differences between referred spouses and spouses contacted directly mirrored service member referring characteristics.

Differences by HIV serostatus in coronary artery disease severity and likelihood of percutaneous coronary intervention following stress testing

BACKGROUND

HIV-infected persons develop coronary artery disease (CAD) more commonly and earlier than uninfected persons; however, the role of non-invasive testing to stratify CAD risk in HIV is not well defined.

METHODS AND RESULTS

Patients were selected from a single-center electronic cohort of HIV-infected patients and uninfected controls matched 1:2 on age, sex, race, and type of cardiovascular testing performed. Patients with abnormal echocardiographic or nuclear stress testing who subsequently underwent coronary angiography were included. Logistic regressions were used to assess differences by HIV serostatus in two co-primary endpoints: (1) severe CAD (≥70% stenosis of at least one coronary artery) and (2) performance of percutaneous coronary intervention (PCI). HIV-infected patients (N = 189) were significantly more likely to undergo PCI following abnormal stress test when compared with uninfected persons (N = 319) after adjustment for demographics, CAD risk factors, previous coronary intervention, and stress test type (OR 1.85, 95% CI 1.12-3.04, P = 0.003). No associations between HIV serostatus and CAD were statistically significant, although there was a non-significant trend toward greater CAD for HIV-infected patients.

CONCLUSIONS

HIV-infected patients with abnormal cardiovascular stress testing who underwent subsequent coronary angiography did not have a significantly greater CAD burden than uninfected controls, but were significantly more likely to receive PCI.

Equivocal tests after contrast stress-echocardiography compared with invasive coronary angiography or with CT angiography: CT calcium score in mildly positive tests may spare unnecessary coronary angiograms

Background

Imaging stress tests are not ideally accurate to predict anatomically obstructive CAD, leading to a non-trivial rate of unnecessary iCA. This may depend on the threshold used to indicate iCA, and maybe CTA or, one step earlier, CT calcium score could spare most unnecessary iCA in only mildly positive cSE. We assessed the diagnostic accuracy of contrast stress-echocardiography (cSE) in comparison with invasive coronary angiography (iCA), and CT angiography (CTA) only in case of equivocal tests, to find hints helping reduce falsely positive cSE in the suspicion of coronary artery disease (CAD).

Methods

Patients who were indicated cSE for suspected CAD between 2012 and 2016, who also underwent iCA were selected and diagnostic results compared. A second group, specifically with equivocal cSE who underwent CTA was also analyzed.

Results

137 subjects with equivocal cSE and CTA and 314 with cSE (any result) and iCA were selected. In the CTA-equivocal cSE group, an Agatston score < 105 and a coronary flow reserve (CFR-LAD) <1.7 had very high negative predictive value (99%, 92% respectively) to exclude obstructive CAD. The Agatston score was the most significant incremental predictor of CAD beyond clinical variables (chi square 31 to 47, p < 0.001). In the iCA group a more-than-mild reversible wall motion abnormality (WMA) demonstrated high positive predictive value for CAD (89%), while CFR-LAD appeared less useful. More-than-mild reversible WMA was the most significant predictor of CAD beyond clinical variables (chi square 37.5 to 56, p < 0.001).

Conclusions

Our data suggest iCA should be indicated only for more-than-mild reversible WMA at cSE, due to the very high positive predictive value for CAD of this finding, while mildly positive tests should be shifted to non-invasive CT, with CTA performed only for coronary calcium Agatston score > 100, since lower scores demonstrated very high negative predictive value for CAD, not justifying proceeding to CTA and even less to iCA.

Utility of a Precision Medicine Test in Elderly Adults with Symptoms Suggestive of Coronary Artery Disease

BACKGROUND

Diagnosing obstructive coronary artery disease (CAD) is challenging in elderly adults, and current diagnostic approaches for CAD expose these individuals to risks from contrast dye and invasive procedures.

DESIGN

A Registry to Evaluate Patterns of Care Associated with the Use of Corus CAD in Real World Clinical Care Settings (PRESET; NCT01677156), pragmatic clinical trial.

SETTING

Community, 21 primary care practices.

PARTICIPANTS

Of 566 stable, nonacute outpatients presenting with symptoms suggestive of obstructive CAD, the 176 who were aged 65 and older (median age 70, 61% female) were the current study participants.

INTERVENTION

Blood-based precision medicine test, incorporating age, sex, and gene expression score (ASGES) to improve clinical decision-making and quality of care.

MEASUREMENTS

Information on demographic characteristics, clinical factors, ASGES results (range 1-40; low (≤15), high (>15)), referral patterns to cardiology and advanced cardiac testing, and major adverse cardiac events (MACEs) was collected in a subgroup analysis of elderly adults in the PRESET Registry. Follow-up was for 1 year after ASGES testing.

RESULTS

Median ASGES was 25, and 40 (23%) participants had a low score. Clinicians referred 12.5% of participants with a low ASGES and 49.3% with a high ASGES to cardiology or advanced cardiac testing (odds ratio for referral = 0.12, P < .001, adjusted for participants demographics and clinical covariates). Higher scores were associated with greater likelihood of posttest cardiac referral. At 1-year follow-up, the incidence of a MACE or revascularization was 10% (13/136) in the high ASGES group and 0% (0/40) in the low ASGES group (P = .04).

CONCLUSION

The ASGES test showed potential clinical utility in the evaluation of elderly outpatients with symptoms suggestive of obstructive CAD. Test use may reduce unnecessary referrals and the risk of procedure-related complications in individuals with low ASGES, who are unlikely to benefit from further testing, while also identifying individuals who may benefit from further cardiac evaluation and management.

Clinical Utility of a Precision Medicine Test Evaluating Outpatients with Suspected Obstructive Coronary Artery Disease

BACKGROUND

Identifying patients with obstructive coronary artery disease can be challenging for primary care physicians. Advances in precision medicine may help augment clinical tools and redefine the paradigm for evaluating coronary artery disease in the outpatient setting. A blood-based age/sex/gene expression score (ASGES) incorporating key features of precision medicine has shown clinical validity with a 96% negative predictive value and 89% sensitivity in estimating a symptomatic patient's current likelihood of obstructive coronary artery disease. To better characterize the clinical utility of the ASGES and measure its impact on clinician decision-making, a community-based registry was established.

METHODS

The prospective PRESET Registry (NCT01677156) enrolled stable, nonacute adult patients presenting with typical or atypical symptoms suggestive of obstructive coronary artery disease from 21 US primary care practices from August 2012 to August 2014. Demographics, clinical characteristics, and ASGES results (predefined as low [ASGES ≤15] or elevated [ASGES >15]) were collected, as were referrals to Cardiology or further functional/anatomic cardiac testing after ASGES testing. Patients were followed for 1 year post ASGES testing.

RESULTS

Among the 566-patient cohort (median age 56 years), clinicians referred 26/252 (10%) of patients with low scores vs 137/314 (44%) of patients with elevated scores to Cardiology or advanced cardiac testing for further evaluation (unadjusted odds ratio 0.15, P <.0001; adjusted odds ratio after accounting for clinical covariates = 0.18, P <.0001). Data on 84 patients referred for advanced cardiac testing showed abnormal findings in 0 of 13 (0%) low ASGES and 10 of 71 (14%) elevated ASGES patients. Major adverse cardiovascular events and revascularization were noted in 3/252 (1.2%) patients with low ASGES and 14/314 (4.5%) patients with elevated ASGES score (P <.03).

CONCLUSIONS

In this community-based cardiovascular registry, the ASGES demonstrated clinical utility in the evaluation of patients with suspected obstructive coronary artery disease. Low-score patients were less likely to undergo cardiac referral, were unlikely to have positive findings on further cardiac work-up, and had a low rate of adverse cardiovascular events in 1-year follow-up. Our work provides evidence supporting the value of using precision medicine in the delivery of cardiovascular care.

[Recommendations of the ESC guidelines regarding cardiovascular imaging]

Cardiac imaging plays a key role in the diagnosis and risk stratification in the ESC guidelines for the management of patients with stable coronary artery disease. Demonstration of myocardial ischaemia guides the decision which further diagnostic and therapeutic strategy should be followed in these patients. One should, however, not forget that there are no randomised studies supporting this type of management. In patients with a low pretest probability coronary CT angiography is the optimal tool to exclude coronary artery stenoses rapidly and effectively. In the near future, however, better data is needed showing how much cardiac imaging is really necessary and how cost-effective it is in patients with stable coronary artery disease.

Accuracy of Computed Tomographic Angiography and Single-Photon Emission Computed Tomography-Acquired Myocardial Perfusion Imaging for the Diagnosis of Coronary Artery Disease

BACKGROUND

Establishing the diagnosis of coronary artery disease (CAD) in symptomatic patients allows appropriately allocating preventative measures. Single-photon emission computed tomography (CT)-acquired myocardial perfusion imaging (SPECT-MPI) is frequently used for the evaluation of CAD, but coronary CT angiography (CTA) has emerged as a valid alternative.

METHODS AND RESULTS

We compared the accuracy of SPECT-MPI and CTA for the diagnosis of CAD in 391 symptomatic patients who were prospectively enrolled in a multicenter study after clinical referral for cardiac catheterization. The area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of CTA and SPECT-MPI for identifying patients with CAD defined as the presence of ≥1 coronary artery with ≥50% lumen stenosis by quantitative coronary angiography. Sensitivity to identify patients with CAD was greater for CTA than SPECT-MPI (0.92 versus 0.62, respectively; P<0.001), resulting in greater overall accuracy (area under the receiver operating characteristic curve, 0.91 [95% confidence interval, 0.88-0.94] versus 0.69 [0.64-0.74]; P<0.001). Results were similar in patients without previous history of CAD (area under the receiver operating characteristic curve, 0.92 [0.89-0.96] versus 0.67 [0.61-0.73]; P<0.001) and also for the secondary end points of ≥70% stenosis and multivessel disease, as well as subgroups, except for patients with a calcium score of ≥400 and those with high-risk anatomy in whom the overall accuracy was similar because CTA's superior sensitivity was offset by lower specificity in these settings. Radiation doses were 3.9 mSv for CTA and 9.8 for SPECT-MPI (P<0.001).

CONCLUSIONS

CTA is more accurate than SPECT-MPI for the diagnosis of CAD as defined by conventional angiography and may be underused for this purpose in symptomatic patients.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00934037.

Clinical Utility of Enhanced Relative Activity Recovery on Systolic Myocardial Perfusion SPECT: Lessons from PET

SPECT and PET myocardial perfusion images show greater myocardial intensity and homogeneity in systole than diastole because of greater systolic myocardial thickness, less partial volume loss, and enhanced activity recovery. Consequently, conventional myocardial perfusion images obtained from whole cardiac cycles have lower myocardial intensity and greater heterogeneity than systolic images. Considering relative activity distribution on SPECT systolic images may add clinical utility to whole-cycle images and wall motion.

METHODS

Patients undergoing coronary angiogram within 4 mo after SPECT myocardial perfusion imaging were reviewed. Images were interpreted by 2 masked interpreters using a 17-segment, 5-point scale to determine summed rest scores (SSS), summed stress scores, and summed difference scores on conventional and systolic images in 603 patients (55.6% no coronary artery disease [no-CAD] and 44.4% CAD). Studies were considered normal when the SSS was less than 4 and summed difference score was less than 2.

RESULTS

In the no-CAD group, systolic SSS was lower than SSS from conventional images (2 ± 2.3 vs. 3 ± 2.6, P < 0.001). In contrast, SSS derived from systolic and conventional images were not different in the obstructive CAD group (9.1 ± 7.6 vs. 9.2 ± 7.4, P = 0.559). When systolic images were considered, true-negative studies increased from 27.2% to 43.3% (P < 0.001) whereas false-positive studies decreased from 28.4% to 12.3% (P < 0.001). True-positive (38% vs. 37.2%, P = 0.505) and false-negative studies (6.5% vs. 7%, P = 0.450) were not significantly changed. Diagnostic accuracy increased from 65.2% to 80.8% (P < 0.001).

CONCLUSION

For gated SPECT myocardial perfusion imaging, when relative activity distribution on systolic images was considered, false-positive studies were reduced and diagnostic accuracy was improved.

New insights from major prospective cohort studies with cardiac CT

Each year, 11 million patients present in the USA with new symptoms suggestive of obstructive coronary artery disease (CAD). Most undergo stress testing but <10% demonstrate myocardial ischemia. Moreover, up to 60% will have CAD which adversely affects outcomes. Cardiac computed tomography (CCT) is being used increasingly as an alternative to stress testing to rule out obstructive CAD in symptomatic patients, and large cohort studies in asymptomatic patients have identified burden of coronary atherosclerosis as a predictor of major adverse cardiovascular events (MACE). This review article will critically evaluate major clinical studies on the use of CCT in both symptomatic and asymptomatic patients and discuss the lessons for the clinical use of CCT.

Propensity score matching: a conceptual review for radiology researchers

The propensity score is defined as the probability of each individual study subject being assigned to a group of interest for comparison purposes. Propensity score adjustment is a method of ensuring an even distribution of confounders between groups, thereby increasing between group comparability. Propensity score analysis is therefore an increasingly applied statistical method in observational studies. The purpose of this article was to provide a step-by-step nonmathematical conceptual guide to propensity score analysis with particular emphasis on propensity score matching. A software program code used for propensity score matching was also presented.

The diagnosis of CAD in women: addressing the unmet need - a report from the national expert roundtable meeting

A multistakeholder panel comprising experts in the fields of clinical cardiology, medical technology innovation, women's health research and policy analysis, personalized medicine, payers (including self-insured employers), patient advocacy, and health economics was convened at the Heart House in Washington, DC. The following points emerged as key concepts: (1) Diagnostic challenges in the evaluation of women with symptoms suggestive of obstructive coronary artery disease (CAD) result from: (a) presentation with atypical symptoms and lower pretest probability of disease compared to men, (b) fatty tissue and breast tissue attenuation on cardiac imaging leading to false positive findings, and (c) the presence of microvascular CAD. (2) Diagnostic challenges lead to both over-testing of low-risk women and under-testing of high-risk women. (3) Efforts should be directed toward increasing clinician, clinical professional society, and consumer awareness and understanding of sex-specific differences between men and women in the pathophysiology of CAD. (4) Multiple health care stakeholders should be made aware of new advances in genomic approaches to address the challenges of diagnosing obstructive CAD; specifically, the Corus CAD gene expression test, which was shown to have high sensitivity and negative predictive value in a recent clinical trial. As such, it has promise as a tool to help clinicians to rule out obstructive CAD as a cause of a patient's symptoms. (Population Health Management 2015;18:86-92).

Physician decision making and trends in the use of cardiac stress testing in the United States: an analysis of repeated cross-sectional data

BACKGROUND

Cardiac stress testing, particularly with imaging, has been the focus of debates about rising health care costs, inappropriate use, and patient safety in the context of radiation exposure.

OBJECTIVE

To determine whether U.S. trends in cardiac stress test use may be attributable to population shifts in demographics, risk factors, and provider characteristics and evaluate whether racial/ethnic disparities exist in physician decision making.

DESIGN

Analyses of repeated cross-sectional data.

SETTING

National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey (1993 to 2010).

PATIENTS

Adults without coronary heart disease.

MEASUREMENTS

Cardiac stress test referrals and inappropriate use.

RESULTS

Between 1993 to 1995 and 2008 to 2010, the annual number of U.S. ambulatory visits in which a cardiac stress test was ordered or performed increased from 28 per 10,000 visits to 45 per 10,000 visits. No trend was found toward more frequent testing after adjustment for patient characteristics, risk factors, and provider characteristics (P = 0.134). Cardiac stress tests with imaging comprised a growing portion of all tests, increasing from 59% in 1993 to 1995 to 87% in 2008 to 2010. At least 34.6% were probably inappropriate, with associated annual costs and harms of $501 million and 491 future cases of cancer. Authors found no evidence of a lower likelihood of black patients receiving a cardiac stress test (odds ratio, 0.91 [95% CI, 0.69 to 1.21]) than white patients, although some evidence of disparity in Hispanic patients was found (odds ratio, 0.75 [CI, 0.55 to 1.02]).

LIMITATION

Cross-sectional design with limited clinical data.

CONCLUSION

National growth in cardiac stress test use can largely be explained by population and provider characteristics, but use of imaging cannot. Physician decision making about cardiac stress test use does not seem to contribute to racial/ethnic disparities in cardiovascular disease.

PRIMARY FUNDING SOURCE

National Heart, Lung, and Blood Institute and the National Center for Advancing Translational Sciences.

Cost effectiveness of a gene expression score and myocardial perfusion imaging for diagnosis of coronary artery disease

BACKGROUND

Over 3 million patients annually present with symptoms suggestive of obstructive coronary artery disease (oCAD) in the United States (US), but a cardiac etiology is found in as few as 10% of cases. Usual care may include advanced cardiac testing with myocardial perfusion imaging (MPI), with attendant radiation risks and increased costs of care. We estimated the cost effectiveness of CAD diagnostic strategies including "no test," a gene expression score (GES) test, MPI, and sequential strategies combining GES and MPI.

METHODS

We developed a Markov-based decision analysis model to simulate outcomes and costs in patients presenting to clinicians with symptoms suggestive of oCAD in the US. We estimated quality-adjusted life years (QALYs), total costs, and incremental cost-effectiveness ratios (ICERs) for each strategy.

RESULTS

In our base case, the 2-threshold GES strategy is the most cost-effective strategy at a threshold of $100,000 per QALY gained, with an ICER of approximately $72,000 per QALY gained relative to no testing. Myocardial perfusion imaging alone and the 1-threshold strategy are weakly dominated. In sensitivity analysis, ICERs fall as the probability of oCAD increases from the base case value of 15%. The ranking of ICERs among strategies is sensitive to test costs, including the time cost for testing. The analysis reveals ways to improve on prespecified GES thresholds.

CONCLUSIONS

Diagnostic testing for oCAD with a novel GES strategy in a 2-threshold model is cost effective by conventional standards. This diagnostic approach is more efficient than usual care of MPI alone or a 1-threshold GES strategy in most scenarios.