PAY1 indicates the expected primary payer (Medicare, Medicaid, private insurance, etc.). To ensure uniformity of coding across data sources, PAY1 combines detailed categories in the more general groups. For example,

• Medicare includes both fee-for-service and managed care Medicare patients.
• Medicaid includes both fee-for-service and managed care Medicaid patients.
• Private insurance (PAY1 = 3) includes Blue Cross, commercial carriers, and private HMOs and PPOs.
• Other (PAY1 = 6) includes Worker's Compensation, CHAMPUS, CHAMPVA, Title V, and other government programs.

The HCUP data element PAY1_X retains the expected primary payer as provided by the data source. The State Specific Notes for PAY1 include information on how the source values contained in the PAY1_X are recoded into the HCUP uniform values of PAY1.

When there is a generic category for managed care such as "HMO/PPO" reported under PAY1_X, it is mapped to private insurance (PAY1 = 3) in the HCUP databases. However, it is possible that hospitals may inadvertently include patients covered by a Medicare managed care program administered by a private insurance company under a generic managed care category.

In the 1988-1997 data, the data element PAY1_N provides more detailed categories for private insurance and other payers. This data element is discontinued beginning in the 1998 data because of the difficulty of coding the information uniformly across States.

If information on secondary or tertiary payers is provided by the data source, the coding of the associated HCUP variables (PAY2, PAY2_X, PAY3, and PAY3_X) is included under the State Specific Notes for PAY1.