THE IMPACT OF THE MEDICARE SHARED SAVINGS PROGRAM ON STROKE OUTCOMES: FINDINGS FROM GET WITH THE GUIDELINES–STROKE REGISTRY Brystana G. Kaufman A dissertation submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Health Policy and Management in the Gillings School of Global Public Health. Chapel Hill 2018 Approved By: Sally Stearns Emily O’Brien Ying Xian Morris Weinberger Mark Holmes © 2018 Brystana G. Kaufman ALL RIGHTS RESERVED ii ABSTRACT Brystana G. Kaufman: The Impact of the Medicare Shared Savings Program on Stroke Outcomes: Findings from Get With the Guidelines–Stroke Registry (Under the direction of Sally Stearns) Background: Over 900 Accountable Care Organizations (ACOs) have been created since 2010, and projections estimate that ACOs will manage the care for about one-third of Americans by 2025, however the impact of the MSSP on quality of care and patient outcomes is unclear. Objective: This study compared outcomes before and after MSSP implementation for patients who were either (1) discharged from hospitals that chose to participate (N=273) versus not participate(N=1,490) in MSSP or (2) assigned by Centers for Medicare & Medicaid Services (CMS) to a MSSP ACO versus not. I hypothesized that MSSP ACO participation would be associated with reduced inpatient utilization and improved outcomes of care. Methods: Using a difference-in-difference (DD) design, I evaluated outcomes associated with MSSP in a national inpatient stroke registry, Get With The Guidelines (GWTG)–Stroke, linked with Medicare claims for 2010–2015. Usage outcomes of discharge to home, number of hospital admissions, and Days Alive and Out of Hospital (DAOH) were modeled using negative binomial models with a log link and offset. Outcomes of all-cause rehospitalization, recurrent stroke, and all-cause mortality were modeled using Cox proportional hazards models. Outcomes of CMO or hospice enrollment within two weeks, hospice use within one year of hospitalization, hospice enrollment within seven days of death, and live discharge from hospice were modeled iii using logistic regression. Except for discharge destination, all outcomes were followed for up to one year following discharge, with appropriate adjustment for death. Key Findings: I found no evidence that hospital participation in the MSSP decreased inpatient use among stroke patients in the year following discharge, however beneficiary ACO alignment was associated with increases in subsequent admissions. Among patients most likely to benefit from palliative care, MSSP increased hospice enrollment and inpatient comfort measures without increasing rates of live discharge. Conclusion: Except for increased use of palliative care among stroke patients, current quality metrics and incentives in MSSP contracts may not be sufficient to generate changes in post-stroke care. iv ACKNOWLEDGEMENTS This dissertation is dedicated to my children, through whose births I became aware of the opportunity for improvement in the value of the care provided in the United States healthcare system, and my husband, who supported my leap into the strange world known as academia. He never doubted I would emerge successful, and the reason I did is largely due to his confidence when mine wavered. I owe the completion of this work to the many mentors, colleagues, and funders who supported this project and my development as a researcher. First I thank my dissertation committee: Sally Stearns, Emily O’Brien, Morris Weinberger, Mark Holmes, and Ying Xian. Each of them has played a remarkable role in my progression to this stage. Before I knew where I wanted to be in the public health labyrinth, Morris advised me, wisely, to enter the Master’s program where I gained insight and confidence. Before I had a curriculum vitae, Mark gave me an opportunity to practice and learn from the best researchers who of course worked at the North Carolina Rural Health Research Center (shout out to George Pink). Sally has been in the trenches with me as I struggled through my first complex claims analyses in my Master’s project, and she supported my vision for this dissertation work and made it better every step of the way. Emily was a key contributor to the design of my study, encouraging me to be ambitious and connecting me with the people and data that made my ideas come to life. Ying has provided essential clinical perspective and data knowledge and, in addition, I appreciate his encouragement and support in my transition into the next stage of my research career. v Additionally, I must thank Donald Taylor, Jeff Clough, Roland Matsouaka, Steven Spivack, Paula Song, and the Get With The Guidelines leadership and statistical teams who served as a consultants on this project and provided valuable feedback. This dissertation benefitted from their generosity of time and expertise immensely. In addition to direct project support, Don has provided mentorship and strategic direction for my long-term career goals. I appreciate the generous funding that provided the resources and time for me to complete this study. First, the Duke-Margolis center funded the hospice data that were needed for Aim 3. Supplemental funding for consulting, administration, and travel was provided through the Executive Director Pathway Award at the Duke Clinical Research Institute. The DCRI pre- doctoral fellowship program gave me access to all of these resources, and I cannot thank Asheley Skinner enough for her role in establishing this program. Finally, the many therapy sessions and random escapist conversations with Ruchir and Mihaela, as fellows at the DCRI, made the process nearly enjoyable at times. All the HPM students and my cohort in particular provided wonderful support, and I am excited to see what they will accomplish in the future. “Knowing is not enough; we must apply. Willing is not enough; we must do.” —Goethe vi PREFACE This dissertation is organized in a non-traditional format. The first chapter provides a brief introduction to the topic and the specific aims of the dissertation. Chapter 2 includes the conceptual model and an overview of the approach taken in each study aim. Chapters 3, 4, and 5 are manuscripts for the three study aims, intended to stand alone as publishable manuscripts and thus have redundancies with other chapters. Chapter 6 provides a summary of findings and policy implications and suggestions for future research. The Get With The Guidelines®–Stroke (GWTG–Stroke) program is provided by the American Heart Association/American Stroke Association. GWTG–Stroke is sponsored, in part, by Medtronic and has been funded in the past through support from Boeringher-Ingelheim, Merck, Bristol-Myers Squib/Sanofi Pharmaceutical Partnership, Janseen Pharmaceutical Companies of Johnson & Johnson and the AHA Pharmaceutical Roundtable. vii TABLE OF CONTENTS LIST OF TABLES ......................................................................................................................... xi LIST OF FIGURES ...................................................................................................................... xii LIST OF ABBREVIATIONS ...................................................................................................... xiii CHAPTER 1. INTRODUCTION ................................................................................................... 1 1.1 Background ................................................................................................................... 1 1.2 Study Purpose and Specific Aims ................................................................................. 2 1.3 Study Significance ........................................................................................................ 3 1.4 Research Question and Hypotheses .............................................................................. 4 1.5 Conceptual Model ......................................................................................................... 4 CHAPTER 2. APPROACH ............................................................................................................ 8 2.1 Overview and Rationale ................................................................................................ 8 2.2 Innovation ..................................................................................................................... 9 2.3 Data Sources ............................................................................................................... 11 2.4 Sample Size and Power ............................................................................................... 11 Sample Identification .................................................................................................. 11 Limited Life Expectancy Subgroup ............................................................................ 14 Power .......................................................................................................................... 18 2.5 Selection Bias.............................................................................................................. 19 CMS MSSP Assignment Methodology ...................................................................... 19 MSSP Immortal Time Bias ......................................................................................... 21 2.6 Key Variables and Measures .....................................................................................