Error DRGs–what are they for?

Introduction The DRG system is based on the list of MDCs (Main Diagnosis Categories) defined on the basis of the principal diagnosis. At the same time, the surgical procedure is typically accepted in one or more MDCs. Thus, the cases with the same procedure code can be assigned to different DRGs depending on the principal diagnoses. In the NordDRG system, some DRGs (error DRGs) are reserved for cases where none of the operating room procedures performed during a hospital stay is related to the principal diagnosis. The groupings to these DRGs are placed after the regular MDC definitions. There are seven PostMDC rules in the NordDRG system which result within the normal MDC groups. The error DRGs are intended to capture atypical cases, or those not occurring with sufficient frequency to represent a distinct, recognizable clinical group. However, very often the reason for assignment to these groups is an error in the use of the basic classifications. In the study, the cases assigned to DRG 468 (the name in the NordDRG Estonian 2003 version is ‘Extensive O. R. procedure unrelated to principal diagnosis’, which was changed in 2004 to ‘Rare or incorrect combination of diagnosis and extensive procedure’) were investigated. Since the implementation of the NordDRG system in Estonia (in 2004 for reimbursement), every year 260 to 370 cases are assigned to DRG 468 amounting to 1-3% of the all inpatient and day-surgery cases assigned to the ca 500 DRGs listed in the NordDRG Estonian 2003 version. The division of DRG 468 cases by medical specialties shows that more than 50% of the DRG 468 discharges are in oncology, general surgery and urology. As for the setting of the care, the vast majority (94-95%) of the DRG 468 cases are treated in hospital settings. The rest are day-surgery cases. The aims of the study were as follows: 1. To detect the assignment errors – How many cases should have been assigned to another DRG due to inappropriate coding? 2. To determine the direction of errors – Did the cases incorrectly assigned to DRG 468 result in over or under payments to hospitals? 3. To determine the source of coding errors – Was the incorrect assignment to DRG 468 related to inappropriate use of diagnoses or procedure codes?