The Major Diagnostic Category, Version 10 (MDC10) is assigned by the HCFA DRG Grouper algorithm during HCUP processing. Refer to the notes for the data element DRG10 for complete details. MDC10 is available on the HCUP databases from 1988 to 1999.

Labels

Labels for the MDCs are provided as an ASCII file in HCUP Tools: Labels and Formats.

One discharge in 1991 with an invalid principal diagnosis code (DXV1=1) and at least one non-missing secondary diagnosis code (DX2, etc.) had the incorrect DRG10 and MDC10 assigned because of a error in HCUP processing. The DRG10 should have been 470; and the MDC10 should have been equal to 0.

No other years are affected.

Some 1989-1990 discharges with a missing principal diagnosis code (DX1=" ") and at least one non-missing secondary diagnosis code (DX2, etc.) have the incorrect DRG10 and MDC10 assigned because of an error in HCUP processing. The DRG10 should be 470; and the MDC10 should be equal to 0. The following numbers of records are affected:

• 1 record in 1989 and
• 1 record in 1990.

No other years are affected.

Some 1988-1991 discharges with an invalid principal diagnosis code (DXV1=1) and at least one non-missing secondary diagnosis code (DX2, etc.) have the incorrect DRG10 and MDC10 assigned because of an error in HCUP processing. The DRG10 should be 470; and the MDC10 should be equal to 0. The following numbers of records are affected:

• for 1988, 34 records;
• for 1989, 30 records;
• for 1990, 44 records; and
• for 1991, 33 records.

Beginning with 1992 discharges, DRG10 and MDC10 were processed correctly.

Some 1988-1992 discharges with an invalid principal diagnosis code (DXV1 = 1) and at least one non-missing secondary diagnosis code (DX2, etc.) have the incorrect DRG and MDC assigned because of an error in HCUP processing. The DRG should be 470; and the MDC should be equal to 0. The following numbers of records are affected:

• for 1988, 184 records;
• for 1989, 68 records;
• for 1990, 13 records;
• for 1991, 1 record; and
• for 1992, 1 record.

Beginning with 1993 discharges, DRG10 and MDC10 were processed correctly.

According to source documentation, the principal and secondary procedures for one hospital (DSHOSPID="056" and HOSPID=55155) are incorrect in the fourth quarter of 1997. System problems at the hospital caused the last procedure coded on the medical record to be stored as the principal procedure. No secondary procedures were recorded. This affects the DRG, DRG10, MDC, and MDC10 assignment.

Some 1989-1992 discharges with an invalid principal diagnosis code (DXV1=1) and at least one non-missing secondary diagnosis code (DX2, etc.) have the incorrect DRG10 and MDC10 assigned because of an error in HCUP processing. The DRG10 should be 470; and the MDC10 should be equal to 0. The following numbers of records are affected:

• for 1989, 23 records;
• for 1990, 4 records;
• for 1991, 1 record; and
• for 1992, 10 records.

Beginning with 1993 discharges, DRG10 and MDC10 were processed correctly.