The association of ICU acuity and organizational factors with outcomes of low-risk patients

Abstract

OBJECTIVE: Outcomes of low-risk patients may be affected by the overall acuity of the ICU to which they were admitted. Studies addressing this topic are very scarce and the underlying mechanisms supporting this association remain incompletely understood. Here, we investigated the effects of ICU acuity (defined as the mean Simplified Acute Physiology Score 3 of all admitted patients in the bimester in which a given patient was admitted) and organizational factors on the outcomes of patients with a low risk of dying admitted to ICUs.

DESIGN: Retrospective cohort study.

SETTING: One hundred and thirty-four ICUs from Brazil and Uruguay.

PATIENTS: All low-risk (defined as a Simplified Acute Physiology Score 3 probability of death < 3%) patients admitted between 2016 and 2018.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: The primary outcome was hospital mortality; secondary outcomes were ICU mortality, and ICU and hospital lengths of stay (LOS). ICU acuity was evaluated as a continuous variable. Multilevel multivariable regression analyses were used to explore the association between ICU acuity, organizational characteristics, and outcomes. Of 285,553 patients, 69,675 (24.4%) were considered low risk. Elective surgeries (66.2%) were the main admission reason. In the models adjusted for patient- and ICU-level characteristics, ICU acuity was not associated with hospital mortality (odds ratio [OR] = 1.095 [0.942–1.274]) and all secondary outcomes. These results were consistent in sensitivity analyses. The presence of dedicated pharmacists in the ICU (OR = 0.531 [0.365–0.773]) and the number of implemented clinical protocols (OR = 0.817 [0.688–0.970]) were independently associated with lower hospital mortality. Clinical protocols were also associated with shorter ICU and hospital LOS.

CONCLUSIONS: ICU acuity was not associated with outcomes in low-risk patients. Appropriate multidisciplinary staffing coupled with adherence to best clinical practices are essential to optimize efficiency and minimize variability of care for this population.