Time-to-readmission and Mortality After High-risk Surgery

Retrospective cross-sectional cohort study using 5 years of Medicare benficiary data to determine whether post discharge mortality varies by time-to-readmission. Two of the three operations analyzed were lung resection (n=101,092) and coronary artery bypass grafting (CABG) (n=484,260). Patients were categorized as follows: no readmission within 30 days, readmitted within 1-5 days, 6-10 days, 11-15 days, 16-20 days, and 21-30 days. The main analysis examined the association between risk-adjusted mortality and the time-to-readmission categories. The secondary analysis examined whether major complications during the index hospitalization predicted mortality. The overall readmission rate for lung resection was 10.8% and for CABG was 14%. The major findings of this study are: 1) Patients who were readmitted had higher risk-adjusted mortality than nonreadmitted patients (10.8% versus 3.7%), 2) Risk-adjusted mortality decreased in a linear manner as the time-to-readmission increased, and 3) Interestingly, there was only a weak association between postoperative complications during the index hospitalization and readmission.