Frequently Asked Questions

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How does the Medicaid Analytic eXtract (MAX) accurately and correctly identify program enrollees in Medicaid and CHIP?

This question generally asks if MAX is the “gold standard” for identifying and counting Medicaid and CHIP program enrollees by various characteristics (e.g. age, gender, basis of eligibility, Medicaid/Medicare dual enrollee status, etc). While there are some flaws in MSIS and MAX data, we believe that these data are of very high quality in terms of correctly identifying Medicaid enrollees. We believe that the MSIS requirements, MAX enhancements and data quality reviews at several levels produce high quality MAX data. However, the MSIS and MAX data are derived from data in MMIS and other state systems and cannot be more complete and consistent than the data originating from those state systems.  MSIS requires states to submit data for all Medicaid enrollees and Medicaid expansion Child Health Insurance Program (M-CHIP) enrollees.

States are given the option to report eligibility data for separate stand-alone CHIP (S-CHIP) enrollees in MSIS.  Some of the States that have S-CHIP programs have elected to provide enrollment data on at least some of their S-CHIP enrollees in MSIS. Data users can determine which States are submitting enrollment for at least some of their S-CHIP enrollees by examining the MAX validation reports for the Person Summary file.  However, states are instructed not to report any claims for non-Medicaid covered services (e.g. claims for services provided to S-CHIP) at this time. States report aggregate statistics for CHIP enrollees in the State Enrollment Data System (SEDS). There are current efforts under way in the MAX-PDQ contract and through the release of an updated MSIS Data Dictionary to improve S-CHIP reporting.

Unique Identifiers

MSIS requirements for state reporting are that each program enrollee should be assigned one and only one Medicaid Identifier (ID) that is permanent for the life of the enrollee. The state may choose to use either the person’s Social Security Number (SSN) or a state assigned ID as the unique ID. If the state chooses to use a state assigned ID, SSN must still be reported. If the state chooses to use SSN as the unique ID, the state must report a temporary ID that is assigned by the state while application is being made to SSA for a permanent SSN. This is a recurring issue for newborns who do not receive SSNs immediately at birth. For newborns and any other enrollees who are assigned temporary IDs, the state must submit both temporary ID and SSN on a quarterly eligibility record for the person so that the temporary ID and the SSN can be cross-referenced for the same enrollee. In MAX, temporary IDs (from MSIS quarterly submissions) are replaced with permanent SSNs for all quarters of the calendar year. This may be a problem if there is only a temporary ID for all quarters of the calendar year and a permanent SSN has not yet been reported in MSIS.

MSIS quarterly eligibility submissions include both correction records for prior quarters and retroactive eligibility determinations. These records are reported in MSIS for the quarters in which the transactions occurred. The MAX processing moves these records into the proper time sequence to show actual months of enrollment for each month in the calendar year.

Identifying Dual Enrollees

MSIS reporting of dual enrollment (Medicare and Medicaid) has been challenging for several reasons. Some states have identified a large percentage of dual enrollees as unknown by type of dual status (e.g. QMB +, QMB only, SLMB +, SLMB only, etc). Also, a few states have reported no dual enrollees as having full Medicaid coverage. In contrast, it is expected that > 85% of dual enrollees in every state should have full Medicaid coverage. One state did not identify any dual enrollees in Fiscal 1999. The Center for Medicaid and State Operations is working with states to improve the quality of these data for 2003 and later years. Beginning with 1996, SMRF (and MAX) enrollment data have been linked to the Medicare Enrollment Database (EDB) to verify and improve identification of dual enrollees.

Specific Issues

The reality of MSIS reporting does entail some inconsistencies in state reported data. To the extent possible these problems are addressed in MAX production, as follows:

• State assigned IDs may be unique within a single state, but, by chance, two different

states could assign the same ID to different persons. Likewise, an individual may move from state to state, resulting in two different state assigned IDs for the same person. These problems are not currently resolved in MSIS or MAX because data files are created for individual states. However, the problems are easily resolved in MSIS and MAX for multi-state analyses for most enrollees by using the enrollee’s SSN rather than the state assigned ID.

• Despite the requirements to assign a permanent ID to a person for life, some states that choose the option to use state assigned IDs do re-enumerate their enrollees on occasion. Whenever it is determined that such re-enumerations occur, a cross-reference file is requested from the state that is used in MAX to create a consistent ID for each unique enrollee over time. SSNs are used to assist in this process. Wherever possible, this problem is resolved in MAX. When it is not possible to resolve the problem in MAX, the MAX anomaly reports contain helpful information for data users.

• For some dual enrollees, some spouses incorrectly report the Medicare Claim Account Number (CAN) from an account on which they receive auxiliary benefits (as a spouse, widow, child, etc.) as their own SSN. For example, a spouse will report her husband’s SSN as though it were her SSN. The MAX process of linking to the Medicare Enrollment Data Base (EDB) is a two-step process that resolves most of these errors.

• States generally report SSNs for a very high percentage of their program enrollees. For 1999, across all states, about 92.5 percent of enrollment records contain SSNs. Excluding California, 95.5 percent of enrollment records contain SSNs. For California, the percentage was about 78 percent of California’s 7.3 million enrollees. There may be various reasons why SSN is not reported for some Medicaid enrollees in MSIS. The largest group without SSNs is probably undocumented aliens, many of whom may receive only emergency care from Medicaid. This is particularly the case for Medicaid in California. There is no reasonable way to resolve the problem of missing SSNs in either in MSIS or in MAX.


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