Survival of mechanically ventilated ward patients and association with organisational factors: a multicentre prospective study

OBJECTIVES: Determine 90-day mortality of mechanically ventilated ward patients outside the intensive care unit (ICU) and its association with organisational factors. DESIGN: Multicentre prospective observational study of mechanically ventilated ward patients. Modified Poisson regression was used to assess association between nurse to patient ratio (NPR) and 90-day mortality, adjusted for designated medical team, Society of Critical Care Medicine (SCCM) triage priority and centre effect. NPR was divided into low (1:9.6 to 1:10), medium (1:6 to 1:8) and high (1:2.6). Sensitivity analysis was conducted for pneumonia with or without acute respiratory distress syndrome (ARDS) to assess magnitude of association. SETTING: 7 acute public hospitals in Hong Kong. PARTICIPANTS: All 485 mechanically ventilated patients in wards from participating hospitals between 18 January 2016 and 17 April 2016 were recruited. Three hundred patients were included after excluding patients with limitation of therapy within 24 hours of intubation. MAIN OUTCOMES: 90-day mortality, Mortality Prediction Model III Standardised mortality ratio (MPMIII(0) SMR). RESULTS: 201 patients died within 90 days after intubation (67.0%, 95% CI 61.5% to 72.1%), with MPMIII(0) SMR 1.88, 95% CI 1.63 to 2.17. Compared with high NPR, medium and low NPRs were associated with higher risk of 90-day mortality (adjusted relative risk (RR(adj)) 1.84, 95% CI 1.70 to 1.99 and 1.64, 95% CI 1.47 to 1.83, respectively). For 114 patients with pneumonia with or without ARDS, low to medium NPR, too sick to benefit from ICU (SCCM priority 4b), no ICU consultation and designated medical team were associated with risk of 90-day mortality (RR(adj) 1.49, 95% CI 1.40 to 1.58; RR(adj) 1.60, 95% CI 1.49 to 1.72; RR(adj) 1.34, 95% CI 1.27 to 1.40; RR(adj) 0.85, 95% CI 0.78 to 0.93, respectively). CONCLUSION: The 90-day mortality rates of mechanically ventilated ward patients were high. NPR was an independent predictor of survival for mechanically ventilated ward patients.