In- and out-hospital mortality rate in surgical patients

Death rates after surgery are increasingly analysed for clinical audit and quality assessment. Many studies commonly provide information only on deaths that occur during hospital stay, known as in-hospital death rates. By using hospital data set linked to death certificate registry, we recorded in- and out-hospital deaths within 30 and 60 post-operative days.

The study included all consecutive surgical procedures (denominator) under general or locoregional anaesthesia in adult patients admitted for elective or non-elective inpatient surgery. Patients undergoing planned day-case surgery or obstetrical procedures were excluded. The primary outcome was 30- and 60-day post-operative mortality rate (numerator) whether before or after discharge.

The study material consisted of a sample of 36,494 surgical procedures corresponding to 28,202 patients. At 30-day, 384 (crude mortality rate of 1.1%) patients died, 314 (82%) during their hospitalisation and 70 (18%) after discharge. Factors that were associated with in-hospital mortality are ASA scores, emergency, duration of surgery and rate of admission to critical care unit. Within the 30-60 days interval, we recorded 231 supplemental deaths, 103 (45%) after discharge.

In-hospital mortality alone is an incomplete measure of mortality even within 30 days of care. To identify the missing deaths, hospital records need to be linked to data from death certificate. This connection with the national death registry will allow obtaining the rate of in-hospital and out-hospital death.