Factors Associated With Participation in Cardiac Episode Payments Included in Medicare’s Bundled Payments for Care Improvement Initiative

Key Points

Question  Are hospitals participating in Medicare’s Bundled Payments for Care Improvement initiative for cardiac bundles different from nonparticipating hospitals in ways that could limit the generalizability of program outcomes to all US acute care hospitals?

Findings  In this cross-sectional study, participation in Bundled Payments for Care Improvement model 2 bundled payments for acute myocardial infarction, congestive heart failure, coronary artery bypass graft surgery, and percutaneous coronary intervention was associated with larger hospital size, non–safety net hospital status, and access to cardiac catheterization laboratories.

Meaning  Outcomes of cardiac bundled payments included in Bundled Payments for Care Improvement may have limited external validity, particularly among small and safety net hospitals with more limited cardiac capabilities.

Importance  Medicare’s Bundled Payments for Care Improvement (BPCI) is a voluntary pilot program evaluating bundled payments for several common cardiovascular conditions. Evaluating the external validity of this program is important for understanding the effects of bundled payments on cardiovascular care.

Objective  To determine whether participants in BPCI cardiovascular bundles are representative of US acute care hospitals and identify factors associated with participation.

Design, Setting, and Participants  Retrospective cross-sectional study of hospitals participating in BPCI model 2 bundles for acute myocardial infarction (AMI), congestive heart failure (CHF), coronary artery bypass graft, and percutaneous coronary intervention and nonparticipating control hospitals (October 2013 to January 2017). The BPCI participants were identified using data from the Centers for Medicare and Medicaid Services, and controls were identified using the 2013 American Hospital Association’s Survey of US Hospitals. Hospital structural characteristics and clinical performance data were obtained from the American Heart Association survey and Centers for Medicare and Medicaid Services. One hundred fifty-nine hospitals participating in BPCI model 2 cardiac bundles and 1240 nonparticipating control hospitals were compared, and a multivariable logistic regression was estimated to identify predictors of BPCI participation.

Exposures  Bundled payments.

Main Outcomes and Measures  Hospital-level structural characteristics and 30-day risk-adjusted readmission and mortality rates for AMI and CHF.

Results  Compared with nonparticipants, BPCI participants were larger, more likely to be privately owned or teaching hospitals, had lower Medicaid bed day ratios (ratio of Medicaid inpatient days to total inpatient days: 17.0 vs 19.3; P < .001), and were less likely to be safety net hospitals (2.5% vs 12.3%; P < .001). The BPCI participants had higher AMI and CHF discharge volumes, were more likely to have cardiac intensive care units and catheterization laboratories, and had lower risk-standardized 30-day mortality rates for AMI (13.7% vs 16.6%; P = .001) and CHF (11.3 vs 12.4; P = .005). In multivariable analysis, larger hospital size and access to a cardiac catheterization laboratory were positively associated with participation. Being a safety net hospital was negatively associated with participation (odds ratio, 0.3; 95% CI, 0.1-0.7; P = .001).

Conclusions and Relevance  Hospitals participating in BPCI model 2 cardiac bundles differed in significant ways from nonparticipating hospitals. The BPCI outcomes may therefore have limited external validity, particularly among small and safety net hospitals with limited clinical cardiac services.

The United States spends more than $200 billion on cardiovascular disease care annually.¹ Bundled payments hold promise for curbing rising health care costs.² In 2013, the Center for Medicare and Medicaid Services (CMS) launched Bundled Payments for Care Improvement (BPCI), a voluntary pilot evaluating the feasibility and efficacy of 4 bundled payment models across 48 clinical conditions.³ Model 2 bundles, the most widely subscribed, subsume the index hospitalization, associated readmissions, and postacute care and include bundles for common cardiovascular conditions and procedures.³

Selective participation represents a potential threat to the external validity of voluntary programs, including BPCI. Prior work suggests that hospitals participating in BPCI may not broadly represent all US acute care hospitals.^4,5 Investigating participation bias in BPCI Model 2 cardiac bundles is critical for understanding the generalizability of cost and quality outcomes from this pilot and may help policymakers mitigate this bias when designing and implementing future programs, such as BPCI Advanced, a voluntary bundled payment pilot CMS plans to launch in October 2018.⁶ Whether participation bias exists in BPCI Model 2 cardiac bundles is unknown.

We compared hospitals participating in BPCI Model 2 bundled payments for acute myocardial infarction (AMI), congestive heart failure (CHF), coronary artery bypass graft surgery (CABG), and percutaneous coronary intervention (PCI) with nonparticipants in their health care markets to identify structural and performance characteristics associated with BPCI participation.

This study was approved by the institutional review board at the Harvard School of Public Health. Medicare claims data had been deidentified prior to use, and informed consent was therefore waived. We used publicly available data from CMS to identify all hospitals that enrolled in BPCI Model 2 bundles for AMI, CHF, CABG, and PCI between October 1, 2013, and January 31, 2017. Using data from the American Hospital Association’s (AHA) Survey of US Hospitals from 2010 to 2013, we identified nonparticipating acute care hospitals in hospital referral regions with at least 1 BPCI participant. Critical access hospitals were excluded. We obtained data on hospital structural characteristics and clinical performance from the AHA survey and CMS’ Hospital Compare website including 30-day risk-standardized mortality and readmission rates and clinical volumes for AMI and CHF (list of covariates provided in eAppendix in the Supplement). Data on each hospital’s disproportionate share payment were obtained from 2014 Medicare claims. We defined safety net hospitals (SNHs) as having disproportionate sharepayments in the top 10% of hospitals nationally. We compared the structural characteristics and clinical outcomes of BPCI participants and control hospitals using t tests, Wilcoxon tests, and χ² tests. We considered a 2-tailed P value less than .05 to be statistically significant. We constructed a multivariable logistic regression model to identify predictors of participation in BPCI Model 2 cardiac bundles. For categorical variables with missing data, we included a missing category alongside other categories in the regression. We excluded patients missing data for one or more continuous variables.

We identified 159 different hospitals participating in BPCI Model 2 cardiac bundles and 1240 control hospitals. Thirty hospitals participated in CABG bundles, 34 in PCI bundles, 52 in AMI bundles, and 114 in CHF bundles; 52 hospitals participated in at least 2 of these bundles.

Compared with nonparticipants, BPCI participants were larger and more likely to be privately owned and teaching hospitals. Participants had lower Medicaid bed day proportions (17.0% vs 19.3%; P = .004) and were less likely to be SNHs (n = 4 [2.5%] vs n = 121 [9.8%]; P < .001) (Table 1). The BPCI participants had higher mean annual emergency department visits (n = 59 565 vs n = 35 323; P < .001) and higher AMI and CHF discharge volumes and were more likely to have cardiac intensive care units (n = 72 [45.3%] vs n = 315 [25.4%]; P < .001), cardiac catheterization laboratories (n = 140 [88.1%] vs n = 643 [51.9%]; P < .001), and cardiac surgery on site (n = 100 [62.9%] vs n = 371 [29.9%]; P < .001). In addition, BPCI participants had lower risk-standardized 30-day mortality rates for both AMI (13.7% vs 16.6%; P = .001) and CHF (11.3% vs 12.4%; P = .005).

In multivariable analysis, larger hospital size and having a cardiac catheterization laboratory were positively associated with BPCI participation. Being an SNH was strongly and negatively associated with participation (odds ratio, 0.3; 95% CI, 0.1-0.8; P = .01) (Table 2).

The annual costs of treating cardiovascular disease are projected to quadruple to more than $818 billion by 2030.⁷ Curbing this spending without compromising quality is critical to ensuring the financial sustainability of the US health care system. Bundled payments represent a promising approach for improving quality and reducing unnecessary resource use.⁸ The BPCI is the largest study of bundled payments to date.

We found significant differences between BPCI model 2 cardiac bundle participants and comparison hospitals with respect to key cardiac capabilities and mortality rates for common cardiovascular conditions. After multivariable adjustment, participating hospitals were significantly more likely to be larger, non–safety net facilities with cardiac catheterization laboratories.

Despite growing interest in using bundled payments to improve care value, little empirical evidence on the merits and risks of bundled payments for cardiovascular disease care or factors associated with success under this new model exists. Our analysis indicates that selection bias could limit the generalizability of cost and quality outcomes data from BPCI model 2 cardiac bundles.

This study has implications for designing and interpreting outcomes from future alternative payment programs, including BPCI Advanced. Specifically, participation bias represents a threat to future voluntary bundled payment pilots, which may struggle to enroll a broadly representative cohort of hospitals, including small hospitals and SNHs. Smaller hospitals may be less likely to participate in voluntary programs because they treat lower volumes of common cardiovascular diseases, lack the capabilities to treat severe and complex cardiovascular disease, and do not possess the administrative and quality improvement infrastructure to track and rapidly improve performance.^9-11 Additionally, SNHs treat outsized proportions of poor and underserved patients, and bundled payment risk adjustment methods do not account for social risk factors.^12,13 Finally, many hospitals contract with private physician groups to staff their facilities rather than directly employing clinicians. This arrangement can complicate efforts to incent high performance within bundles and reduce administrators’ enthusiasm to participate in these pilots. These and other barriers must be mitigated to achieve broader participation in future pilots.

Policymakers could address these barriers in a few ways. First, they could adjust payments to account for patient-level social risk factors affecting quality and cost outcomes, which could alleviate concerns managers of SNHs have about participating in pilots.¹⁴ Second, future pilots, including BPCI Advanced, could offer quality improvement assistance or limits to downside risk for underrepresented hospitals to entice them to participate. Third, future pilots could include separate tracks for larger non-SNHs and smaller SNHs; separating these facilities would ensure that hospitals with fundamentally different missions, clinical capabilities, and patient populations are not forced to compete against each other. Fourth, policymakers could reintroduce bundled payment programs with mandatory participation; however, while mandatory participation could solve the generalizability problem, payment adjustments for social determinants of health and quality improvement assistance may still be needed to help some hospitals succeed.

This study has limitations. First, our comparisons of clinical outcomes and patient populations treated were limited to publicly available data. Second, we did not have data necessary to compare baseline costs of care across BPCI participants and nonparticipants and cannot evaluate differences in care value. Third, we cannot rule out confounding owing to unmeasured covariates.

Hospitals participating in bundled payments for AMI, CHF, CABG, and PCI through BPCI model 2 are larger, less likely to be SNHs, and have greater cardiac capabilities. Selection bias may limit efforts to use BPCI outcomes data to understand how bundled payments affect quality and costs of cardiovascular disease care across a diverse cohort of delivery systems.

Corresponding Author: Daniel M. Blumenthal, MD, MBA, Division of Cardiology, Massachusetts General Hospital, 55 Fruit St, Yawkey Bldg, Ste 5B, Boston, MA 02114 (dblumenthal1@mgh.harvard.edu).

Accepted for Publication: May 9, 2018.

Published Online: June 27, 2018. doi:10.1001/jamacardio.2018.1736

Author Contributions: Dr Blumenthal 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.

Concept and design: Blumenthal.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: Oseran, Blumenthal.

Statistical analysis: Howard, Blumenthal.

Obtained funding: Blumenthal.

Administrative, technical, or material support: Oseran, Blumenthal.

Supervision: Blumenthal.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Blumenthal is the Associate Chief Medical Officer of Devoted Health, a Medicare Advantage Insurance Company. This position is unrelated to the content of this manuscript. No other disclosures were reported.

Funding/Support: This work was supported by the John S. LaDue Memorial Fellowship at Harvard Medical School, Boston, Massachusetts.

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.