In the FY 2008 Hospital Inpatient Prospective Payment System Final Rule, CMS revised the existing complication/comorbidity (CC) listing and established three different levels of severity into which diagnosis codes would be divided. The three levels are MCC (Major CC) CC and non-CCs. MCCs reflect the highest level of severity while non-CCs reflect the lowest. It was noticed that non-CC diagnosis codes do not significantly affect severity of illness or resource use.

Per the Hospital IPPS final rule, the overall statistics by CC group are as follows:

• MCC: 22.2% of patients
• CC: 36.6% of patients
• Non-CC: 41.1% of patients

A complication is defined as a condition that arises during the hospital stay and a comorbid condition is a pre-existing condition. Both of these conditions have been identified as potentially extending the length of hospital stay by at least one day in 75 percent of the cases on average.

A CC/MCC may affect DRG assignment; therefore, it's important that the physician documentation supports the assigned code. The CC/MCC list is updated annually as new codes are assigned to ICD-9-CM.

Click below to see the CC and MCC listings.
CC Listing
MCC Listing