Out-of-office hours' elective surgical intensive care admissions and their associated complications.

Background: The 'weekend' effect is a controversial theory that links reduced staffing levels, staffing seniority and supportive services at hospitals during 'out-of-office hours' time periods with worsening patient outcomes. It is uncertain whether admitting elective surgery patients to intensive care units (ICU) during 'out-of-office hours' time periods mitigates this affect through higher staffing ratios and seniority.

Methods: Over a 3-year period in Western Australia's largest private hospital, this retrospective nested-cohort study compared all elective surgical patients admitted to the ICU based on whether their admission occurred 'in-office hours' (Monday-Friday 08.00-18.00 hours) or 'out-of-office hours' (all other times). The main outcomes were surgical complications using the Dindo-Clavien classification and length-of-stay data.

Results: Of the total 4363 ICU admissions, 3584 ICU admissions were planned following elective surgery resulting in 2515 (70.2%) in-office hours and 1069 (29.8%) out-of-office hours elective ICU surgical admissions. Out-of-office hours ICU admissions following elective surgery were associated with an increased risk of infection (P = 0.029), blood transfusion (P = 0.020), total parental nutrition (P < 0.001) and unplanned re-operations (P = 0.027). Out-of-office hours ICU admissions were also associated with an increased hospital length-of-stay, with (1.74 days longer, P < 0.0001) and without (2.8 days longer, P < 0.001) adjusting for severity of acute and chronic illnesses and inter-hospital transfers (12.3 versus 9.8%, P = 0.024). Hospital mortality (1.2 versus 0.7%, P = 0.111) was low and similar between both groups.

Conclusion: Out-of-office hours ICU admissions following elective surgery is common and associated with serious post-operative complications culminating in significantly longer hospital length-of-stays and greater transfers with important patient and health economic implications.