Postoperative mortality after inpatient surgery: Incidence and risk factors

Abstract

Purpose: This study determined the incidence of and identified risk factors for 48 hour (h) and 30 day (d) postoperative mortality after inpatient operations.

Methods: A retrospective cohort study was conducted using Anesthesiology's Quality Indicator database as the main data source. The database was queried for data related to the surgical procedure, anesthetic care, perioperative adverse events, and birth/death/operation dates. The 48 h and 30 d cumulative incidence of postoperative mortality was calculated and data were analyzed using Chi-square or Fisher's exact test and generalized estimating equations.

Results: The 48 h and 30 d incidence of postoperative mortality was 0.57% and 2.1%, respectively. Higher American Society of Anesthesiologists physical status scores, extremes of age, emergencies, perioperative adverse events and postoperative Intensive Care Unit admission were identified as risk factors. The use of monitored anesthesia care or general anesthesia versus regional or combined anesthesia was a risk factor for 30 d postoperative mortality only. Time under anesthesia care, perioperative hypothermia, trauma, deliberate hypotension and invasive monitoring via arterial, pulmonary artery or cardiovascular catheters were not identified as risk factors.

Conclusions: Our findings can be used to track postoperative mortality rates and to test preventative interventions at our institution and elsewhere.

Keywords: anesthesia; inpatient surgery; operations; postoperative mortality; risk factors.

Figure 1

Risk factors for 48 h and 30 d postoperative mortality. For each panel, the y-axis shows the incidence of mortality (%) 48 h or 30 d postoperatively, and the x-axis shows the ASA PS of the patient (A; 1–5 scale), the patient’s age (B; years), the emergency status of the operation (C), whether the operation was a trauma case (D), whether the patient was hypothermic perioperatively (E), whether a perioperative adverse event occurred (F), and whether the operation resulted in postoperative intensive care unit admission (G). In some panels, the exact percentage is noted with an arrow (eg, “0” refers to “0%”). Notes: The figure legends list the significance levels from chi-square or Fisher’s exact test examining incidence rates across each level of the risk factor. Abbreviations: ASA PS, American Society of Anesthesiologists physical status; d, day; h, hour; NS, not significant.

Figure 2

Risk factors for 48 h and 30 d postoperative mortality. For each panel, the y-axis shows the incidence of mortality (%) 48 h or 30 d postoperatively, and the x-axis shows the anesthesia type (A; MAC, regional anesthesia, general anesthesia or combined), the total time under anesthesia care (B; minutes), the use of invasive monitoring via arterial line (C), cardiovascular catheter (D) or pulmonary artery catheter (E), and whether the operation involved deliberate intraoperative hypotension (F). In some panels, the exact percentage is noted with an arrow (eg, “0” refers to “0%”). Notes: The figure legends list the significance levels from chi-square or Fisher’s exact test examining incidence rates across each level of the risk factor. Abbreviations: d, day; h, hour; MAC, monitored anesthesia care; NS, not significant.