Association of ICU patient-to-clinician ratios with mortality across two US health systems

RATIONALE: The association of interprofessional team member workload with ICU outcomes is understudied.

OBJECTIVE: To evaluate the association of patient-to-intensivist (PIR), patient-to-respiratory therapist (PRTR), and patient-to-clinical pharmacist (PpharmR) ratios with hospital mortality.

METHODS: We conducted a retrospective study of adults admitted from the emergency department to an ICU with acute respiratory failure or sepsis within two US healthcare systems (2013-2018). Our primary exposures were patient-to-clinician ratios (PIR, PRTR, PpharmR) averaged over the ICU stay; our primary outcome was hospital mortality. We used multivariable mixed effects regression with patient-to-clinician ratios modeled as restricted cubic splines (4 knots). We primarily considered each exposure separately, then included all ratios together.

MEASUREMENTS AND MAIN RESULTS: Our cohort included 45,036 patients (mean age 66.0 [standard deviation: 16.6] years, 23,420 [52.0%] male) across 27 ICUs within 24 hospitals. Of these, 29,326 (65.1%) had acute respiratory failure, 32,434 (72.0%) had sepsis, and 9,675 (21.5%) died in hospital. The average PIR was 9.3 (standard deviation, 3.6) and PRTR 7.9 (3.2); average PpharmR was 15.0 (5.5) among patients (n=8,950/45,036) in ICUs with clinical pharmacists (n=8/27). We found no significant association between average daily PIR (Wald test for all spline terms p=0.24) or PRTR (p=0.18) and hospital mortality in the full cohort; similarly, among patients in ICUs with pharmacists, no significant association of PpharmR with mortality (p=0.08). Models including ratios together yielded similar null results.

CONCLUSIONS: We did not identify an association of any average daily patient-to-clinician ratio with hospital mortality for US ICU patients with sepsis or respiratory failure.

National Heart, Lung, and Blood Institute

Hayley B Gershengorn, George L Anesi, Vincent X Liu, Deena K Costa, Erich M Dress, Amy L Dzierba, Robert Fowler, Andrew A Kramer, Danny Lizano, Damon C Scales, Allan Garland, Hannah Wunsch