No weak days? Impact of day in the week on surgical mortality

Studies show increased rates of mortality for admissions on the weekend (WE) versus the weekday (WD). However, scepticism exists of this so-called 'weekend effect' on patient outcome. It remains poorly investigated, particularly the timing of the day of surgery and post-operative outcomes. A UK study found higher odds of death when operated on Friday and the WE, versus WD. This relationship was investigated by interrogating the Australian and New Zealand Audit of Surgical Mortality database.

A standardized tool is used to collect data after every surgical death. Data in this retrospective cohort study from participating private and public hospitals in Australia on elective and emergency operations were extracted and included 7718 patients who had a surgical procedure within 30 days of admission and who subsequently died. A proxy measure of early surgical mortality, namely odds of dying within the first 48 h following surgery, was used to compare surgical mortality across days of the week.

Unadjusted and adjusted odds of early surgical mortality were higher on the WE compared to WD, unadjusted and adjusted OR 1.30 (P < 0.001) and 1.19 (P = 0.026), respectively. When separated by day of week, there was a trend for higher surgical mortality on Friday, Saturday and Sunday versus all other days, although this did not reach statistical significance. ASA grade and specialty of surgery were important predictors of outcome.

There appears to be an association between day of surgery and surgical outcome. The exact cause and contributing factors requires further investigation.