Days alive out of hospital (DAOH) is defined as the number of days a patient spends alive and out of hospital in a predefined period. Current understanding of the performance of this outcome measure in the intensive care (ICU) population is limited thus we aimed to investigate the relationship between DAOH and prognostic indicators in patients admitted to ICU and to compare the performance of DAOH at 30-days (DAOH30), 90-days (DAOH90) and 180-days (DAOH180). In a retrospective cohort study, all patients aged over 18 years admitted to ICU in New Zealand between 1st January 2017 and 31st December 2023 were eligible for inclusion. DAOH was calculated using merged data from the Australian and New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD) and the National Minimum Dataset (NMDS) data. 72,546 admissions recorded in the ANZICS APD were linked to NMDS. Median (interquartile range IQR) DAOH30 was 15 days (0–22), median (IQR) DAOH90 was 72 days (40–81) and median (IQR) DAOH180 was 160 days (117–171). DAOH90 was negatively correlated with age (ρ= -0.19, p < 0.001) and Acute Physiology and Chronic Health Evaluation (APACHE) II score (ρ = -0.42 p < 0.001). DAOH90 was lower in patients receiving invasive ventilation, vasoactive support and renal replacement therapy and those admitted with severe traumatic brain injury (TBI). Lower median DAOH90 was associated with increased variation in outcome across multiple subgroups. A floor effect was observed for DAOH30 (with a median DAOH30 value of zero days) in patients with high APACHE II score, severe TBI and patients undergoing renal replacement therapy or tracheostomy insertion. The time for the excess hazard of hospitalisation and mortality to reach baseline were 37.3 and 18.6 days respectively but were prolonged in certain patient subgroups. Our study provides evidence to support the use of DAOH for patients admitted to ICU, however DAOH30 is unlikely to be a suitable measure.
Brown et al. (Sun,) studied this question.