ÌÇÐÄvlog

Key Points

QuestionÌý Are recently reported declines in rates of cardiac stress testing among Medicare beneficiaries and in a large health maintenance organization universal or confined to the populations studied?

FindingsÌý In this serial cross-sectional study of a large cohort of commercially insured patients aged 25 to 64 years, we observed a 3.0% increase in the rate of cardiac stress testing from 2005 to 2012.

MeaningÌý Trends in cardiac stress testing may be driven more by unique characteristics of health systems and populations than by national efforts by physician groups to reduce overuse of testing.

ImportanceÌý After a period of rapid growth, use of cardiac stress testing has recently decreased among Medicare beneficiaries and in a large integrated health system. However, it is not known whether declines in cardiac stress testing are universal or are confined to certain populations.

ObjectiveÌý To determine trends in rates of cardiac stress testing among a large and diverse cohort of commercially insured patients.

Design, Setting, and ParticipantsÌý A serial cross-sectional study with time trends was conducted using administrative claims from all members aged 25 to 64 years belonging to a large, national managed care company from January 1, 2005, to December 31, 2012. Linear trends in rates were determined using negative binomial regression models with procedure count as the dependent variable, calendar quarter as the key independent variable, and the size of the population as a logged offset term. Data analysis was performed from January 1, 2005, to December 31, 2012.

Main Outcomes and MeasuresÌý Age- and sex-adjusted rates of cardiac stress tests per calendar quarter (reported as number of tests per 100 000 person-years).

ResultsÌý A total of 2 085 591 cardiac stress tests were performed among 32 921 838 persons (mean [SD] age, 43.2 [10.9] years; 16 625 528 women [50.5%] and 16 296 310 [49.5%] men; 7 604 945 nonwhite [23.1%]). There was a 3.0% increase in rates of cardiac stress testing from 2005 (3486 tests; 95% CI, 3458-3514) to 2012 (3589 tests; 95% CI, 3559-3619; P = .01 for linear trend). Use of nuclear single-photon emission computed tomography decreased by 14.9% from 2005 (1907 tests; 95% CI, 1888-1926) to 2012 (1623 tests; 95% CI, 1603-1643; P = .03). Use of stress echocardiography increased by 27.8% from 2005 (709 tests; 95% CI, 697-721) to 2012 (906 tests; 95% CI, 894 to 920; P &±ô³Ù; .001). Use of exercise electrocardiography increased by 12.5% from 2005 (861 tests; 95% CI, 847-873) to 2012 (969 tests; 95% CI, 953-985; P &±ô³Ù; .001). Use of other stress testing modalities increased 65.5% from 2006 (55 tests; 95% CI, 51-59) to 2012 (91 tests; 95% CI, 87-95; P &±ô³Ù; .001). For individuals aged 25 to 34 years, rates of cardiac stress testing increased 59.1% from 2005 (543 tests; 95% CI, 532-554) to 2012 (864 tests; 95% CI, 852-876; P &±ô³Ù; .001). For individuals aged 55 to 64 years, rates of cardiac stress testing decreased by 12.3% from 2005 (7894 tests; 95% CI, 7820-7968) to 2012 (6923 tests; 95% CI, 6853-6993; P &±ô³Ù; .001).

Conclusions and RelevanceÌý In contrast to declines in the use of cardiac stress testing in some health care systems, we observed a small increase in its use among a nationally representative cohort of commercially insured patients. Our findings suggest that observed trends in the use of cardiac stress testing may have been driven more by unique characteristics of populations and health systems than national efforts to reduce the overuse of testing.

Owing to rapid growth in the use of cardiac imaging from 1999 to 2006, cardiac stress tests have become a major focus of the debate on rising health care costs and inappropriate use of health care resources.^1-3 Although recent studies^4-6 conducted among Medicare beneficiaries and in Kaiser Permanente have shown reductions in rates of cardiac stress testing since 2006, it is unknown if these declining rates are universal or confined to certain populations or payment models.

In this study, we examined whether the volume of cardiac stress tests and the modalities of testing have changed among a large and diverse cohort of commercially insured patients. If consistent declines in the use of cardiac stress testing are observed in our population, national efforts led by physicians to reduce overuse, such as dissemination of criteria for appropriate use of cardiac stress testing, may be responsible since such efforts are unlikely to have differential effects between health systems and insurers. On the other hand, if use of cardiac stress testing is stable or increasing in our cohort, organizational characteristics of health systems, including payment models and/or population differences, may be responsible for these changes. We used a nationally representative sample of commercial insurance claims to estimate temporal trends in the annual volume of cardiac stress tests performed between 2005 and 2012.

Data were obtained from the Clinformatics Data Mart (OptumInsight), a database of administrative health claims for members of a large, national managed care company. Administrative claims submitted for payment are verified, adjudicated, and deidentified before inclusion in the Clinformatics Data Mart. The database consists of comprehensive medical claims for approximately 15 million annual covered lives spanning throughout the United States and includes member eligibility, demographic data, and socioeconomic data. For this study, we identified comprehensive administrative claims for all members from January 1, 2005, to December 31, 2012. We excluded patients younger than 25 years owing to the negligible expected likelihood of cardiac stress testing among individuals in this age group and those older than 64 years since Medicare coverage is nearly universal after that age. All other members were included. The study protocol was deemed exempt by the University of Pennsylvania Institutional Review Board. As all data were deidentified, patient consent was not obtained.

All cardiac stress tests performed among the eligible cohort from 2005 to 2012 were identified using Current Procedural Technology codes for exercise electrocardiography, nuclear single-photon emission computed tomography (SPECT), stress echocardiography, cardiac computed tomography angiography, perfusion positron emission tomography, and stress cardiac magnetic resonance (eAppendix in the Supplement). Exercise electrocardiography tests performed within 48 hours of nuclear SPECT or stress echocardiography were considered to be a single imaging stress event.

We calculated the incidence of cardiac stress testing per 100 000 person-years for each calendar quarter. The denominator was defined as all members of the managed care company between the ages of 25 and 64 years who had at least 30 days of membership in the health plan during that quarter. Rates of cardiac stress testing per person-quarter were determined by dividing the total number of cardiac stress tests performed by the denominator in each calendar quarter and were adjusted for age and sex using direct standardization.

Data analysis was performed from January 1, 2005, to December 31, 2012. Differences in characteristics of the overall cohort over time were compared using χ² tests for categorical variables and t tests for continuous variables. Linear trends in the annual rates of cardiac stress tests were assessed using negative binomial regression models with procedure count as the dependent variable and calendar quarter as the key independent variable. Models were adjusted for age and sex and included the size of the population as a logged offset term. All statistical tests were 2-sided, with P < .05 indicating statistical significance. Analyses were performed using Stata, version 13.1 (StataCorp).

Our study cohort consisted of 32 921 838 members (mean [SD] age, 43.2 [10.9] years; 16 625 528 women [50.5%] and 16 296 310 [49.5%] men; 7 604 945 nonwhite [23.1%]) representing 224.6 million member-quarters of membership from 2005 to 2012. During the study period, 2 085 591 cardiac stress tests were performed (Table 1).

The overall age- and sex-adjusted use of cardiac stress tests increased by a relative rate of 3.0% during the study period (P = .01) (Table 2). Use of cardiac stress testing increased from 2005 (3486 tests per 100 000 person-years; 95% CI, 3458-3514) to a peak in 2009 (3933 tests per 100 000 person-years; 95% CI, 3905-3961) and then slowly declined until 2012 (3589 tests per 100 000 person-years; 95% CI, 3559-3619; P = .01 for linear trend).

Use of nuclear SPECT decreased by 14.9% (1907 tests per 100 000 person-years; 95% CI, 1888-1926) during the study period, peaking in 2008 (2103 tests per 100 000 person-years; 95% CI, 2083-2123) and then steadily declining until 2012 (1623 tests per 100 000 person-years; 95% CI, 1603-1643; P = .03) (Figure, A). Use of stress echocardiography steadily increased by 27.8% from 709 tests per 100 000 person-years (95% CI, 697-721) in 2005 to 906 tests per 100 000 person-years (95% CI, 894 to 920) in 2012 (P &±ô³Ù; .001). Use of exercise electrocardiography steadily increased by 12.5% from 861 tests per 100 000 person-years (95% CI, 847-873) in 2005 to 969 tests per 100 000 person-years (95% CI, 953-985) in 2012 (P &±ô³Ù; .001). Use of alternative imaging modalities increased by 65.5% from 2006 (the first year Current Procedural Technology codes for coronary computed tomography angiography were used; 55 tests per 100 000 person-years; 95% CI, 51-59) to 2012 (91 tests per 100 000 person-years; 95% CI, 87-95; P &±ô³Ù; .001).

For individuals aged 25 to 34 years, rates of cardiac stress testing increased 59.1% from 2005 (543 tests per 100 000 person-years; 95% CI, 532-554) to 2012 (864 tests per 100 000 person-years; 95% CI, 852-876; P < .001) (Figure, B). For individuals aged 35 to 44 years, rates of cardiac stress testing increased by 30.7% from 2005 (1908 tests per 100 000 person-years; 95% CI, 1887-1929) to 2012 (2493 tests per 100 000 person-years; 95% CI, 2471-2515; P &±ô³Ù; .001). For individuals aged 45 to 54 years, rates of cardiac stress testing did not significantly change from 2005 (4482 tests per 100 000 person-years; 95% CI, 4443-4521) to 2012 (4544 tests per 100 000 person-years; 95% CI, 4505-4583). For individuals aged 55 to 64 years, rates of cardiac stress testing decreased by 12.3% from 2005 (7894 tests per 100 000 person-years; 95% CI, 7820-7968) to 2012 (6923 tests per 100 000 person-years; 95% CI, 6853-6993; P &±ô³Ù; .001).

Contrary to recent findings among Medicare beneficiaries and in Kaiser Permanente, our data from a large cohort of commercially insured patients show a small increase in the overall use of cardiac stress tests from 2005 to 2012. Rates of cardiac stress testing increased substantially among patients aged 25 to 44 years and for all modalities except nuclear SPECT. These findings suggest that trends in the use of cardiac stress testing may be driven more strongly by unique characteristics of health systems and populations than national efforts by physician groups to reduce overuse of testing.

Recent studies have revealed that, from 2005 to 2012, there was a nearly 50% relative decline in the use of cardiac stress tests in Kaiser Permanente and a 25% relative decline in the use of cardiac stress tests among Medicare fee-for-service beneficiaries.^4-6 Divergent trends in the use of cardiac stress testing between these populations and our cohort may be explained by differences in the organizational characteristics of the health systems. Integrated health systems, such as Kaiser Permanente, use capitated payment models without direct financial incentives to perform testing, which often leads to lower use of procedures compared with traditional fee-for-service payment models.^7-9 These health systems often emphasize quality measurement and accountability, which could further contribute to declines in use of procedures.

Recent studies also have shown that use of health care resources may be different between Medicare beneficiaries and privately insured patients who are located in the same geographical regions.^10,11 This difference may be owing to hospital consolidation leading to preferential reductions in testing among Medicare beneficiaries since they tend to use more health care resources in general.^12,13

Patients younger than 64 years have not been well represented in previous studies of national trends in cardiac stress testing. However, age alone is unlikely to explain the divergent trends in cardiac stress testing over time since the age groups in our cohort and those previously studied remained largely stable during the study period. More research is needed to understand whether the increase in use of cardiac stress testing among younger patients in our cohort is owing to evolving trends in the detection and surveillance of coronary artery disease or a need for improvement in patient selection for testing.^14,15

Health care policies are often based on data from Medicare beneficiaries. Our study shows that patterns of the use of diagnostic cardiac imaging may be different among commercially insured patients. Furthermore, the disparate trends in use of cardiac stress testing between our population and previously studied cohorts suggest that organizational characteristics of health systems had a greater effect on trends in cardiac stress testing than did physician-led efforts to reduce overuse, such as disseminating appropriate-use criteria of such testing. This finding is consistent with a recent meta-analysis that found that reported rates of appropriate use of cardiac stress imaging tests have not significantly changed since the publication of criteria for appropriate use.¹⁴

We did not have details on the indications for cardiac stress tests and therefore were unable to directly assess rates of appropriateness or the percentage of tests performed for the detection of coronary artery disease. Also, differential enrollment of sicker persons or disenrollment of healthier persons could lead to increases in the use of cardiac stress testing, but these effects could not be accurately determined.

We observed a small increase in the overall use of cardiac stress tests among a large cohort of commercially insured patients. Divergent trends in the use of cardiac stress testing between populations suggest that organizational characteristics of health systems, including payment models, may influence the use of cardiovascular testing. Trends in the use of cardiac imaging derived from single health systems or insurers may not reflect larger practice patterns.

Accepted for Publication: July 22, 2016.

Corresponding Author: Vinay Kini, MD, MS, Division of Cardiovascular Medicine, Hospital of the University of Pennsylvania, 3400 Spruce St, 9021 Gates, Philadelphia, PA 19104 (vinay.kini@uphs.upenn.edu).

Published Online: November 15, 2016. doi:10.1001/jamacardio.2016.3153

Author Contributions: Dr Kini had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Kini, McCarthy, Groeneveld.

Acquisition, analysis, or interpretation of data: Kini, Dayoub, Bradley, Masoudi, Ho, Groeneveld.

Drafting of the manuscript: Kini, McCarthy.

Critical revision of the manuscript for important intellectual content: McCarthy, Dayoub, Bradley, Masoudi, Ho, Groeneveld.

Statistical analysis: Kini, McCarthy, Dayoub, Groeneveld.

Obtained funding: Groeneveld.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Funding/Support: Dr Kini was supported by grant 5T32HL007843-18 from the National Institutes of Health.

Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Previous Presentation: This paper was presented at the American Heart Association Scientific Sessions 2016 meeting; November 5, 2016; New Orleans, LA.