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.