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

OBJECTIVES: To determine if mortality varies by time-to-readmission (TTR).
BACKGROUND: Although readmissions reduction is a national health care priority, little progress has been made toward understanding why only some readmissions lead to adverse outcomes.
METHODS: In this retrospective cross-sectional cohort analysis, we used 2005-2009 Medicare data on beneficiaries undergoing colectomy, lung resection, or coronary artery bypass grafting (n = 1,033,255) to created 5 TTR groups: no 30-day readmission (n = 897,510), less than 6 days (n = 44,361), 6 to 10 days (n = 31,018), 11 to 15 days (n = 20,797), 16 to 20 days (n = 15,483), or more than 21 days (n = 24,086). Our analyses evaluated TTR groups for differences in risk-adjusted mortality (30, 60, and 90 days) and complications during the index admission.
RESULTS: Increasing TTR was associated with a stepwise decline in mortality. For example, 90-day mortality rates in patients readmitted between 1 and 5 days, 6 and 10 days, and 11 and 15 days were 12.6%, 11.4%, and 10.4%, respectively (P < 0.001). Compared to nonreadmitted patients, the adjusted odds ratios (and 95% confidence intervals) were 4.88 (4.72-5.05), 4.20 (4.03-4.37), and 3.81 (3.63-3.99), respectively. Similar patterns were observed for 30- and 60-day mortality. There were no sizable differences in complication rates for patients readmitted within 5 days versus after 21 days (24.8% vs 26.2%, P < 0.001).
CONCLUSIONS: Surgical readmissions within 10 days of discharge are disproportionately common and associated with increased mortality independent of index complications. These findings suggest 10-day readmissions should be specially targeted by quality improvement efforts.