The July Effect for Total Joint Arthroplasty Procedures.

The "July effect" refers to the assumed increased risk of complications during the months when medical school graduates transition to residency programs. The actual existence of a July effect is controversial. With this study, the authors sought to determine whether evidence exists for the presence of a July effect among total joint arthroplasty (TJA) procedures. The 2013 and 2014 Nationwide Readmission Databases were combined and all index primary and revision arthroplasty procedures were identified, and then patients from December were excluded. Thirty-day readmission rates, time to readmission, and readmission costs were analyzed by index procedure month and index procedure type. A total of 1,193,034 procedures (index primary: n=1,107,657; revision arthroplasty: n=85,377) were identified. Among all procedure types, 46,674 (3.9%) 30-day readmissions were observed. Among all procedures, an index procedure with a discharge in July resulted in the highest monthly readmission rate of the year (4.2%), which was significantly higher than the mean annual readmission rate (P<.0001). This effect was most pronounced for primary total knee arthroplasty (3.9% vs 3.6%, P<.0001). When stratifying results into teaching vs nonteaching hospitals, the highest readmission rate occurred if the index procedure occurred at a nonteaching hospital in July (4.5%, P<.0001). These data provide evidence that a July effect appears to exist for TJA procedures and is most pronounced at nonteaching institutions. Based on published mean readmission costs, the total annualized cost variation attributable to the higher readmission rate for primary TJA procedures in July is approximately $18.6 million. [Orthopedics. 2020;43(6):e543-e548.].