OBJECTIVES: Policymakers have expanded readmissions penalties to include elective arthroplasties, but little is known about the risk factors for readmissions following these procedures. We hypothesized that infections after total hip and total knee ((TH/TK) arthroplasty can lead to readmissions and drive up the costs .This study aims to evaluate the proportion of readmissions due to infections following TH/TK arthroplasties. METHODS: Healthcare Cost and Utilization Project- State Inpatient Databases (HCUP-SID) were used for our study. Procedure code '8151' and '8154'  were used to identify all inpatient discharges with total hip arthroplasty and total knee arthroplasty in Florida from 2009 to 2013, Massachusetts from 2010 to 2012, California from 2009 to 2011. Readmission was measured by CMS validated algorithm which included readmitting to any acute care hospital, for any reason, with the exception of certain planned readmissions, occurring within 30 days of the discharge date of the index hospitalization. Infections were identified by ICD-9-CM codes : 99859, 99666, 6826, 0389, 486, 4821, 00845, 5990, 48242, 04111, 04112,04119,0417, 99591, 99592. Descriptive analysis were performed. RESULTS: In California, among patients discharged for TH/TK arthroplasty during 2009 to 2011, 4.29% were readmitted, and 33.02% of the readmissions were for infection. While in Florida during the period of 2009 to 2013, 4.7% were readmitted and 33.39% of the readmissions were for infection. In Massachusetts from 2010 to 2012, the readmission rate was 3.92%, and infection among readmission was 35.2%. Of those readmissions due to infection, MRSA and MSSA together are specifically account for 14.88% in California, 13.11% in Massachusetts and 13.38% in Florida. CONCLUSIONS: The rate of infection is similar across the state of California, Florida and Massachusetts, and it is a leading cause for readmission following THTK procedures. Programs to reduce the likelihood of MRSA or MSSA infection following THTK procedures would likely reduce readmissions due to infection.

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