Impact of Definition and Timeframe on Capturing Surgery-Related Readmissions After Primary Joint Arthroplasty.

BACKGROUND: Readmission rate has emerged as an important metric to measure quality, but varying definitions and timeframes are used. We aimed to evaluate the impact of different readmission definitions (postoperative vs postdischarge) and timeframes (30 vs 90-day) on capturing surgery-related readmissions after primary total joint arthroplasty.

METHODS: Patients who underwent primary total hip or knee arthroplasty between January 1, 2013 and December 31, 2015 were included. The electronic medical records of readmitted patients were reviewed to determine whether a surgery-related event was most responsible for readmission. The performances of 4 definition-timeframe combinations in capturing surgery-related readmissions were evaluated.

RESULTS: A total of 2586 patients were included. Using both postoperative and postdischarge definitions, there were no differences in the proportion of readmissions that were surgery-related when comparing 30 and 90-day timeframes (postoperative: 71% vs 60%, P = .118; postdischarge: 68% vs 60%, P = .219). Greater proportion of readmissions between days 0 and 30 were for surgery-related reasons compared with readmissions between days 31 and 90 using both postoperative and postdischarge definitions (postoperative: 71% vs 47%, P = .005; postdischarge: 68% vs 49%, P = .022). Among 104 patients readmitted for surgery-related reasons within 1 year of discharge, 52% were readmitted within 30 days of surgery compared with 79% within 90 days (P < .001). Similarly, 53% and 81% of readmissions were captured by the 30 and 90-day postdischarge definitions, respectively (P < .001).

CONCLUSION: A 90-day timeframe is superior in capturing surgery-related readmissions after total joint arthroplasty. Important Total hip and knee arthroplasty adverse events may be missed using a 30-day timeframe.