Medicare and You can be found at http://www.medicare.gov/publications/pubs/pdf/10050.pdf.
8 We mention below that medication provided in institutional settings (like during a hospital stay) may be covered by Medicare, but does not necessarily appear in the administrative claims data files used for research purposes.
9 The reader should check the Medicare benefits schedule for the most up-to-date information.
10 See CMS’s Medicare Coverage of Skilled Nursing Facility Care booklet, page 17, available at http://www.medicare.gov/Pubs/pdf/10153.pdf.
11 Medicare claim forms include the CMS-1500 for physician or professional billing and the UB-04 (also known as the CMS-1450) for institutional or technical billing.
12 For more information, see ResDAC’s article at http://www.resdac.org/resconnect/articles/114.
13 Source: CMS’s Prospective Payment Systems-General Information website available at https://www.cms.gov/ProspMedicareFeeSvcPmtGen/.
Chapter 3: An Introduction to Medicare Data
Introduction and Goals of This Chapter
A Note on the Source and Structure of Our Claims Data
Durable Medical Equipment (DME) Data
Skilled Nursing Facility (SNF) Claims Data
Commonly Retained Elements in Administrative Claims Data
Master Beneficiary Summary File
Provider Data
Example: Identification of Emergency Department (ED) Utilization
Example: Identification of Surgical Services
Chapter Summary
Introduction and Goals of This Chapter
This chapter introduces the contents of the Medicare claims and enrollment files we will use for our research programming project. The purpose of this introduction is to build on the explanation of the Medicare program presented in Chapter 2 and further prepare the programmer for using Medicare administrative data to complete our example research programming project. In Chapter 2, we learned the basics of the administration of the Medicare program. We defined Medicare, discussed enrollment, eligibility, and coverage, and provided a very simple sketch of how Medicare pays for services. We also briefly discussed how this information about Medicare influences the content of the data files used throughout the remainder of this book. In this chapter, we will build on those concepts and dive into each Medicare file we will be using for our example research programming project.1 We will review the contents of each data set, including examples of information commonly pulled out of each file for research purposes. We will end with an example of how to use the datasets to identify services provided for a surgery and services provided for a visit to the emergency department.2 Through these examples, we will see that the contents of each file are not always intuitive. Rather, the contents of each file are governed by how the services are billed and paid. We will learn to be cognizant of certain quirks, like the fact that not all services performed in an inpatient hospital appear in the inpatient claims data set. Looking forward, in Chapter 4, we will build on the information presented in this chapter by planning our programming project and, in Chapter 5, we will request the data described in this chapter. In subsequent chapters, we will actually use these data to address the research questions posed by our example project described in Chapter 1. For example, we will load and transform our claims files in Chapter 5, and calculate utilization of services in Chapter 7.
A Note on the Source and Structure of Our Claims Data
Before going into detail about the content of the Medicare administrative claims and enrollment data we will be working with, let’s frame our discussion by identifying the source of our data and the structure of the files we will pretend to request, receive, and work with to complete our project.3 It is important to introduce this conversation now because Medicare data can come from a variety of sources and each source stores and provides the data somewhat differently.
We will explore this topic in much more detail in Chapter 5, but for now it is important to know that, depending on our source of funding and the nature of our project, we could choose from at least four data sources:
CMS’s data distribution contractor (sometimes referred to as the Research Data Distribution Center)
CMS’s Data Extract System (DESY)
CMS’s Virtual Research Data Center (VRDC) system
CMS’s Integrated Data Repository (IDR)
For our purposes, we will assume that we will work with CMS’s Research Data Assistance Center (ResDAC) and CMS’s data distribution contractor to request and obtain our data.4
Medicare claims data created for research purposes are provided by CMS’s data distribution contractor separately by claim type. In other words, separate sets of files are provided for final action non-institutional (Part B carrier and durable medical equipment) and institutional (outpatient, inpatient, skilled nursing facility, home health, and hospice) services. CMS further separates data for each claim type into separate files for base claim and claim line (in the case of the set of non-institutional data files) or revenue center (in the case of the set of institutional data files) detail, resulting in seven sets of files.5
The base claim detail (also known as header-level information) is basically summary information, including information that identifies the claim, the beneficiary who received care, the provider of service, the beginning and ending dates for the services billed on the claim, the diagnoses on the claim, and