Use of present-on-admission indicators for complications after total knee arthroplasty: an analysis of Medicare administrative data.

Administrative data are commonly used to evaluate total joint arthroplasty, but analyses have historically been limited by the inability to capture which conditions were present-on-admission (POA). In 2007 Medicare began allowing hospitals to submit POA information. We used Medicare Part A data from 2008 to 2009 to examine POA coding for three common complications (pulmonary embolism [PE], hemorrhage/hematoma, and infection) for primary and revision total knee arthroplasty (TKA). POA information was complete for 60%-75% of complications. There was no evidence that higher TKA volume hospitals or major teaching hospitals were more likely to accurately code POA data. The percentage of complications coded as POA ranged from 6.4% (PE during index admission for primary TKA) to 68.8% (infection during index admission for revision TKA). Early experience suggests that POA coding can significantly enhance the value of Medicare data for evaluating TKA outcomes.