Short Info: IR-DRG (3M/USA)

The IR-DRG system was originally called IAP-DRG system.

In its second, completely recasted version of 2004, additional IR-DRGs for outpatient care were defined. Yet, these were not systematically subdivided towards severity level anymore, and they were only partially consistent with the inpatient base IR-DRGs.1

In surgical treatments, each Major Diagnostic Category was now defined based on the main procedure (and thus not anymore determined by the principal diagnosis). Hence, the name "DRG" (i. e. "diagnosis related groups") was – strictly speeking – not correct anymore.2 Also, the MDC structure that existed since the beginning was tightened. Instead of 27, only 23 Major Diagnostic Categories were left.

In the 2006 version, a number of 1175 IR-DRGs are defined, of these 789 are for inpatient stays (within 263 base IR-DRGs) and 372 for outpatient treatments. 14 IR-DRGs are used to differentiate cases that are not groupable.