Assessing the Impact of Parity in the Large Group Employer-Sponsored Insurance Market: Final Report. 1. INTRODUCTION


The Paul Wellstone and Pete Domenici Mental Health Parity and Addiction Equity Act of 2008 (MHPAEA) ensures that large group health plans and health insurance issuers offer comparable benefits for mental health (MH) and substance use disorder (SUD) services and medical/surgical services. This legislation builds on prior federal parity legislation from 1996 that removed annual and lifetime dollar limits applied to MH coverage that were not comparable to medical and surgical benefits. MHPAEA extended parity to a broader array of benefits, such as financial limits (e.g., unequal cost sharing), quantitative treatment limits (QTLs, such as visit and stay limits), and processes and techniques for managing care (often called non-quantitative treatment limits or NQTLs). MHPAEA also extended parity to SUD services. MHPAEA states that the financial requirements (FRs) and treatment limitations that apply to these behavioral health (BH) benefits cannot be more restrictive than the predominant requirements and limitations that apply to substantially all medical/surgical benefits.

The overall objective of this work is to assess the impact of MHPAEA on the access, utilization, spending, and reimbursement for BH services in the private large group employer-sponsored insurance market. The specific research questions that guided this investigation are listed in Table 1.

TABLE 1. Study Outcome Dimensions and Research Questions Addressed
Dimension Research Question Addressed
Access How did MHPAEA affect any use of different types of BH services?
Utilization patterns How did MHPAEA affect frequency of use of BH services?
Spending How did MHPAEA affect overall spending on BH services?
Reimbursement How did MHPAEA affect reimbursement rates per unit of MH or SUD services?

Structure of This Report

In this report, we start with an extensive background and the motivation for this study, then describe the methods and findings, and conclude with a discussion and suggestions for future research.

  • In Chapter 2, we outline the background of MHPAEA, including literature to date on changes in insurance benefits following MHPAEA and the impact of these changes on BH services. In this chapter, we also describe how our work builds on and expands previous analyses of the impact of parity.

  • In Chapter 3, we briefly describe the methods we used in our analyses. Detailed descriptions of our methods are provided in Appendix B.

  • In Chapter 4, we present our findings in detail on the impact of MHPAEA on access, utilization, spending, and reimbursement, focusing specifically on outpatient MH and SUD services. Supplemental tables with information on our findings across other types of MH and SUD services are included in Appendix E (and in supplemental files upon request). The detailed methods and results in the appendices are included for individuals who are interested in reviewing the technical components of the work in more detail.

  • In Chapter 5, we discuss the importance of these findings and suggest several areas for future research in this area.

  • For the reader's convenience, Appendix A contains definitions of the acronyms and abbreviations used in this report.

  • Appendix C, Appendix D, and Appendix F contain the diagnosis and drug codes used to define the study populations.