EMERGENCY DEPARTMENT FREQUENT USERS: A LATENT CLASS ANALYSIS AND ECONOMIC EVALUATION TO POTENTIALLY GUIDE UTILIZATION MANAGEMENT INTERVENTIONS A dissertation submitted to Kent State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy By Lauren E. Birmingham August, 2017 Dissertation written by Lauren E. Birmingham B.A., Kent State University, 2009 B.B.A., Kent State University, 2009 M.A., Kent State University, 2010 Ph.D., Kent State University, 2017 Approved by Jonathan VanGeest, PhD, Chair, Doctoral Dissertation Committee Vinay Cheruvu, PhD, Member, Doctoral Dissertation Committee John Hoornbeek, PhD, Member, Doctoral Dissertation Committee Kirk Stiffler, MD, Consultant, Doctoral Dissertation Committee Accepted by Sonia Alemagno, PhD, Dean, College of Public Health* ii Dedication To my parents—thank you for your undying support. There are not many parents that would request a copy of their child’s dissertation with the full intent of reading it and discussing the contents at the next family dinner. Your inherent desire to learn forever has become mine. That is a wonderfult gif to have received. To my husband, Chris—thank you for being my rock. Through all the frustration, indecision, and time spent away from home, you have been a constant source of support. Your encouragement helped me discover my passion and power, and has led to a higher level of life satisfaction than I could have ever imagined. You did not help me weather the storm; you showed me that it was not really storming after all. iii Table of Contents List of Figures ............................................................................................................................................... vi List of Tables ............................................................................................................................................... vii Acknowledgements ...................................................................................................................................... ix Chapter 1: Introduction and Statement of the Problem .............................................................................. 1 Background ............................................................................................................................................... 1 Growth in Emergency Department Utilization: Increases in Size and Scope of Practice ................... 10 Utilization and Cost Issues .................................................................................................................. 16 Focusing on Frequent Users .................................................................................................................... 30 Research Questions ................................................................................................................................ 42 Chapter 2: Review of Literature .................................................................................................................. 43 Characteristics of ED Frequent Users ..................................................................................................... 46 Factors Impacting ED Utilization ............................................................................................................. 55 Cost of Care and Practical Implications of Caring for ED Frequent Users............................................... 69 Creating Better Interventions by Targeting Homogeneous Groups ....................................................... 73 Chapter 3: Methods .................................................................................................................................... 78 Data Sources ........................................................................................................................................... 79 Variables to be used in LCA ................................................................................................................. 80 Statistical Analysis ................................................................................................................................... 88 Model Fit and Model Selection ........................................................................................................... 90 Examination of Grouping Variables and Covariates ........................................................................... 90 iv Group Assignment .............................................................................................................................. 91 Cost Analysis ....................................................................................................................................... 91 Chapter 4: Data Analysis ............................................................................................................................. 93 Latent Class Analysis ............................................................................................................................... 98 Model‐building .................................................................................................................................... 98 Model Selection ................................................................................................................................ 100 Evaluation of Gender as a Grouping Variable ................................................................................... 102 Evaluation of Covariates ................................................................................................................... 103 Final Model ....................................................................................................................................... 104 Differences between Subgroups ....................................................................................................... 106 eNaming th Latent Classes ................................................................................................................ 108 Cost‐Analysis ......................................................................................................................................... 111 Chapter 5: Discussion ................................................................................................................................ 115 Why do this Type of Research? ............................................................................................................. 128 Future Research .................................................................................................................................... 132 Strengths and Weaknesses ................................................................................................................... 134 Conclusion ............................................................................................................................................. 137 References ................................................................................................................................................ 139 v List of Figures Table Number Page Figure 1: Excerpt on Nonemergent ED Visits Overtime ……………………………………………………………. 23 Figure 2: AHA Chartbook: Increasing burden of ED visits and Decreasing supply of EDs, 29 1994‐2014………………………………………………………………………………………………………………………………….. Figure 3: Camden Coalition of Healthcare Providers Cluster Analysis Plot………………………………….. 39 Figure 4: Histogram of 2014 ED Frequent User Visits…………………………………………………………………. 93 vi List of Tables Table 1: Average cost of treating select primary care sensitive conditions in four different 20 medical settings …………………………………………………………………………………………………………………. Table 2: Characteristics and Usage of Medicaid‐insured ED users by the number of Annual 44 ED visits………………………………………………………………………………………………………………………………. Table 3: Demographic Characteristics of ED Users .……………………………………………………………. 45 Table 4: Differences in Costs by the Number of Annual ED Visits………………………………………… 70 Table 5: Primary ICD‐9 Diagnosis Code Categories……………………………………………………………… 82 Table 6: Chronic Disease ICD‐9 Definitions …………………………………………………………………………. 84 Table 7: Charlson Comorbidity Algorithm………………………………………………………………..…………. 87 Table 8: Continuous and Count Descriptive Statistics of the ED Frequent User Population 95 (n=5,731)…………………………………………………………………………………………………………………………….. Table 9: Categorical Demographic Descriptive Variables (n=5,731)……………………………………. 96 Table 10: Categorical Clinically Relevant Descriptive Variables (n=5,731)………………………….. 97 Table 11: Latent Class Model Fit Statistics………………………………………………………………………….. 99 Table 12: Multi‐class Model Fit Statistics…………………………………………………………………………….. 102 Table 13: Odds ratio estimates for the Covariate Socioeconomic Status…………………………….. 104 Table 14: Final Model, Adjusted Latent Class Analysis Class Membershipm & Ite ‐Response 105 Probabilities………………………………………………………………………………………………………………………… Table 15: Descriptive Statistics of Latent Classes………………………………………………………………… 107 vii Table 16: Latent Class Subgroup Names and their Defining Attributes………………………………… 111 Table 17: Cost analysis of ED Frequent User Subgroups……………………………………………………… 112 Table 18: Fixed vs. Variable Costs by ED Frequent User Subgroups…………………………………….. 113 viii Acknowledgements I would first like to express my thanks to my advisor, Dr. Jonathan VanGeest, for his tireless support and encouragement throughout the development of this dissertation. In retrospect, I did not know what I was getting into