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Table 3 Linear mixed model estimates showing the effect of the mean nursing hours per patient day on study outcome measures

From: The impact of nurse staffing levels and nurse’s education on patient mortality in medical and surgical wards: an observational multicentre study

Dependent variablesModel 1Model 2  
Estimate95% CI of est.p-valueEstimate95% CI of est.p-valueΔ AICΔ BIC
Crude mortality−3.043−10.6704.5840.426−2.458− 10.4445.5280.538−33.9−34.1
Unexpected death−0.848−2.3160.6210.252−1.737−3.013− 0.4600.009−32.1− 32.4
Death after CPR−0.631−1.3630.1000.089−0.836−1.576−0.0970.028−12.4− 12.7
Unplanned ICU admission−0.201−3.3992.9970.900−0.063−3.3783.2530.970−30.5−24.8
Death after unplanned ICU admission−0.085−0.7390.5690.7910.047−0.7540.8470.907−3.2−3.5
combined mortality rate−1.525−3.5440.4930.136−2.771− 4.471−1.0710.002−33.9−34.1
Hospital LOS−0.172− 0.9550.6120.661−0.023− 0.8360.7910.955−11.5− 11.8
  1. Estimates of fixed effects, 95% confidence intervals and p-values resulting from two linear mixed models concerning the relation between the mean Nursing Hours Per Patient Day and the patient outcome measures in column one (dependent variables)
  2. Model 1: adjusted for clustering (random effect) and study time (fixed effect)
  3. Model 2: adjusted for clustering (random effect), study time, the proportion of nurse Bachelor hours, nurse assistant HPPD, logistic support staff HPPD, Charlson Comorbidity Index and age (fixed effects)
  4. Δ AIC Akaike’s Information Criterion of model 2 - model 1, Δ BIC Schwarz’s Bayesian Information Criterion of model 2 - model 1
  5. CPR Cardiopulmonary Resuscitation, ICU Intensive Care Unit, LOS Length of Stay (in mean days)