How the high acuity unit changes mortality in the intensive care unit: a retrospective before-and-after study

High acuity units (HAU) are hospital units that provide patients with more acute care and closer monitoring than a general hospital ward but are not as resource intensive as an intensive care unit (ICU). Nevertheless, the impact of opening a HAU on ICU patient outcomes remains poorly defined. We investigated how the creation of a HAU impacted patient outcomes in the ICU.

This historical cohort study compared ICU patient in-hospital mortality, ICU length of stay (LOS), and hospital LOS before and after the creation of a HAU in a tertiary-care hospital with a medical/surgical ICU between 1 January 2013 and 31 December 2017.

Data from 4,380 patients (984 in the pre-HAU group and 3,396 in the post-HAU group) were analyzed. In this cohort of ICU patients, 360 (37%) died in the pre-HAU group before the creation of a HAU, and 1,074 (32%) died in the post-HAU group after the creation of a HAU. The creation of a HAU was associated with lower relative risk of in-hospital mortality (adjusted risk ratio, 0.80; 95% confidence interval [CI], 0.72 to 0.89; P < 0.001). The creation of a HAU was also associated with reduced ICU and hospital LOS with a 12% increase in the rate of ICU discharge (adjusted sub-distribution hazard ratio [SHR], 1.12; 95% CI, 1.02 to 1.23; P = 0.02) and a 26% increase in the rate of hospital discharge (adjusted SHR, 1.26; 95% CI, 1.14 to 1.39; P < 0.001), when accounting for the competing risk of death.

These data support the hypothesis that the creation of a HAU may be associated with reduced in-hospital mortality, ICU LOS, and hospital LOS for ICU patients.