Hospital readmission by method of data collection.

Background: Hospital readmissions are increasingly used to pay hospitals differently. We hypothesized that readmission rates, readmissions related to index admission, and potentially unnecessary readmissions vary by data collection method for surgical patients.

Study Design: Using 3 different data collection methods, we compared 30-day unplanned readmission rates and potentially unnecessary readmissions among colorectal surgery patients at a single institution between July 2009 and November 2011. We compared the NSQIP clinical reviewer method, the University HealthSystem Consortium (UHC) administrative billing data method, and physician medical record review.

Results: Seven hundred and thirty-five colorectal surgery patients were identified with readmission rates as follows: NSQIP 14.6% (107 of 735) vs UHC 17.6% (129 of 735). The NSQIP method identified 9 readmissions not found in billing records because the readmission occurred at another hospital (n = 7) or due to a discrepancy in definition (n = 2). The UHC method identified 31 readmissions not identified by NSQIP because of a broader readmission definition (n = 20) or were missed by reviewers (n = 11). The NSQIP method identified 72% of readmissions as related to index admission and physician chart review identified 83%. The UHC method identified 51% of readmissions as related to index admission and physician chart review identified 86%. Sixty-six of 129 UHC readmissions (51%) were deemed potentially preventable; based on physician chart review, 112 of 129 readmissions (87%) were deemed clinically necessary at the time of presentation. Most readmissions were due to surgical site infections (46 of 129 [36%]) and dehydration (30 of 129 [23%]). With improved patient-care efforts, 41 of 129 (31.8%) complications might not have required readmission.

Conclusions: Readmission rates and unnecessary readmissions vary depending on data collection methodology. Reimbursements based on readmission should use standardized and fair methods to minimize perverse incentives that penalize hospitals for appropriate care of high-risk surgical patients.