Patient-to-intensivist ratios can influence patient mortality


CLINICAL QUESTION: Is there variation in patient-to-intensivist ratios (PIR) across ICUs, and does that ratio affect hospital mortality?

BACKGROUND: Most studies show that intensivists improve ICU patient outcomes. With increasing ICU patients but stable intensivist staffing, patient-to-intensivist ratios are increasing. It is unclear if that rising ratio is adversely affecting patient mortality.

STUDY DESIGN: Multicenter retrospective cohort analysis.

SETTING: ICUs in the United Kingdom from 2010 to 2013.

SYNOPSIS: In 94 ICUs, 49,686 adults were examined. The PIR was defined as the total number of patients cared for by an intensivist during day time hours. However, PIR was also calculated using nine variations of the definition, which took into account new admissions and severity of illness, among other factors. A multivariable mixed-effect logistic regression was used to assess the association of PIR and mortality.

The median PIR was 8.5 but varied substantially – PIRs were often larger. The association between PIR and mortality was U shaped. There was a decrease in mortality as the PIR reached 7.5, after which the mortality increased again. The higher mortality with very low PIRs could reflect a volume-outcome relationship. Less patients could mean less experience, different levels of ancillary staff, and so on.

This study did not take into account the possible differences in the multidisciplinary makeup of the ICU teams that would affect the intensivist’s level of responsibility.

BOTTOM LINE: There seems to be an optimal PIR for mortality, though that optimal number would likely depend on the ancillary staff, level of trainees, and patient acuity.

CITATIONS: Gershengorn HB, Harrison DA, Garland A, et al. “Association of Intensive Care Unit Patient-to-Intensivist Ratios With Hospital Mortality.” JAMA Intern Med. 2017 Mar 1;177(3):388-96.

Dr. Tsien is assistant professor in the division of hospital medicine, Loyola University Chicago, Maywood, Ill.