U.S. Department of Health and Human Services

Using MSIS Data to Analyze Medicaid Eligibility and Managed Care Enrollment Patterns in 1999

Appendix A. Overview of MSIS: Reporting Requirements and Information Submitted by States

In the Balance Budget Act of 1997, Congress required that all State Medicaid programs submit electronic eligibility and claims data to the Centers for Medicare &Medicaid Services (CMS). The Medicaid Statistical Information System (MSIS) at CMS is the repository for these data. States submit quarterly eligibility records and claims to MSIS in a fixed electronic format. All States participated in MSIS in Federal Fiscal Year 1999 (FFY 1999), although New York did not begin submitting data until the second quarter (January-March 1999). About 30 states were participating in MSIS prior to FFY 1999 on a voluntary basis. MSIS data are used by CMS for many purposes, including the preparation of the annual CMS-2082 report that provides basic statistical information on Medicaid eligibles and services across states.

States prepare MSIS files in a format specified by CMS, following detailed instructions included in the MSIS data dictionary (http://cms.hhs.gov/medicaid/msis/msisdd99.pdf). Much of the information submitted to MSIS is derived from state Medicaid Management Information Systems (MMIS). However, states are required to submit claims for all Medicaid services provided, even if the services are administered by other state agencies or provided under managed care. Five primary MSIS data files are submitted by each state each quarter:

• Inpatient hospital claims,
• Long-term care claims,
• Prescription drug claims,
• Other non-institutional claims, and
• Eligibility.

Each person enrolled in Medicaid must be assigned a unique personal identifier by a state. This unique identifier must be consistently used to identify that individual, even if that individual is re-enrolled in a subsequent time period. Any claim submitted for an individual must include the unique personal identifier. With the personal identifier, individual enrollment records and claims can be linked over time. Unique identifiers are also required for all service providers submitting claims included in MSIS files.

At CMS, MSIS data are run through a series of prescribed edits. These "error tolerance edits" measure the proportion of records with missing values and invalid values. In addition, certain relational edits check for consistency within records. Detected errors are appended to the MSIS files. Files that exceed prescribed error tolerance limits are rejected, and must be resubmitted by states until they are determined acceptable by CMS. CMS also utilizes a technical assistance contractor (Mathematica Policy Research, Inc.) to perform additional data quality review.

All of the information used in this report comes from MSIS eligibility files. The following key information is included in MSIS eligibility files for each individual enrollee:

• MSIS identification number
• Date of birth
• Date of death
• Sex
• Race/ethnicity
• Social Security number
• County of residence
• Zip code
• Dual eligible flag
• Health Insurance Claim (HIC) identification number for Medicare enrollees
• Monthly information on state and federal eligibility group, private health insurance status, Temporary Aid to Needy Families (TANF) receipt, enrollment in managed care plan(s), managed care plan(s) identification number, and eligibility for the State Children's Health Insurance Program (SCHIP).

For this project, MPR combined quarterly enrollment data from MSIS files for all calendar-year quarters from 1999 and whatever 1999 enrollment data was included in subsequent quarterly files submitted by states. This allowed the study to track individual enrollment across the calendar year, through changes in eligibility group, and to focus on changes in managed care enrollment during the study year.