Patterns and predictors of stress testing modality after percutaneous coronary stenting: data from the NCDR(®)

Abstract

Objectives: We evaluated temporal trends and geographic variation in choice of stress testing modality after percutaneous coronary intervention (PCI), as well as associations between modality and procedure use after testing.

Background: Stress testing is frequently performed post-PCI, but the choices among available modalities (electrocardiography only, nuclear, or echocardiography; pharmacological or exercise stress) and consequences of such choices are not well characterized.

Methods: CathPCI Registry(®) data were linked with identifiable Medicare claims to capture stress testing use between 60 and 365 days post-PCI and procedures within 90 days after testing. Testing rates and modality used were modeled on the basis of patient, procedure, and PCI facility factors, calendar quarter, and Census Divisions using Poisson and logistic regression. Post-test procedure use was assessed using Gray's test.

Results: Among 284,971 patients, the overall stress testing rate after PCI was 53.1 per 100 person-years. Testing rates declined from 59.3 in quarter 1 (2006) to 47.1 in quarter 4 (2008), but the relative use of modalities changed little. Among exercise testing recipients, adjusted proportions receiving electrocardiography-only testing varied from 6.8% to 22.8% across Census Divisions; and among exercise testing recipients having an imaging test, the proportion receiving echocardiography (versus nuclear) varied from 9.4% to 34.1%. Post-test procedure use varied among modalities; exercise electrocardiography-only testing was associated with more subsequent stress testing (13.7% vs. 2.9%; p < 0.001), but less catheterization (7.4% vs. 14.1%; p < 0.001) than imaging-based tests.

Conclusions: Modest reductions in stress testing after PCI occurring between 2006 and 2008 cannot be ascribed to trends in use of any single modality. Additional research should assess whether this trend represents better patient selection for testing or administrative policies (e.g., restricted access for patients with legitimate testing needs). Geographic variation in utilization of stress modalities and differences in downstream procedure use among modalities suggest a need to identify optimal use of the different test modalities in individual patients.

Figure 1. Population flow diagram

Flow diagram showing the process used to define the study population. CMS = Centers for Medicare & Medicaid Services, FFS = fee for service, PCI = percutaneous coronary intervention, PET = positron emission tomography, MRI = magnetic resonance imaging, ECG = electrocardiogram

Figure 2. Temporal trend in stress testing rate

Temporal trend in incidence of stress testing between 61 and 365 days post PCI not preceded by repeat revascularization or catheterization. Incidence rates ratios are calculated both unadjusted and adjusted for patient, procedural, facility, and geographic characteristics using Poisson regression models; they refer to the relative rate of stress testing among patients alive during the calendar quarter who have not yet received a stress test. IRR = incidence rate ratio, CI = 95% confidence interval

Figure 3. Temporal trends in stress testing modality

Trends in percentage of stress tests performed with (A) Exercise ECG versus Exercise Imaging, (B) Pharmacologic Stress with Imaging versus Exercise Stress with Imaging, (C) Exercise Echocardiography versus Exercise Nuclear Testing, based on calendar quarter in which stress test was performed. Odds ratios were calculated both unadjusted and adjusted for patient, procedural, facility, and geographic characteristics using logistic regression. OR = odds ratio, CI = 95% confidence interval.

Figure 4. Relationship between imaging modality and time since PCI

Trends in the percentage of stress tests performed with exercise electrocardiography, exercise imaging, or pharmacologic imaging, based on number of months between patient’s index percutaneous coronary intervention procedure and stress test. ECG = electrocardiography

Figure 5. Geographic Variation in Stress Testing Modalities

Adjusted probability of receiving (A) Exercise ECG versus Exercise Imaging, (B) Pharmacologic Stress versus Exercise Stress with Imaging, (C) Exercise Nuclear versus Exercise Echocardiography, based on US Census Division. Dotted line indicates cohort mean. ECG = electrocardiography, Pharm. = pharmacologic stress testing, Echo = echocardiography