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Table 2 Three sequential random effects and multilevel Cox regression models were used to evaluate the impact of frailty on both 30-days survival

From: The impact of frailty on survival in elderly intensive care patients with COVID-19: the COVIP study

 

Model 1 unadjusted HR (95% CI)

p value

Model 2 adjusted HR (95% CI)

p value

Model 3 adjusted HR (95% CI)

p value

Survival at 30 days

 Vulnerable versus fit

1.75 (1.35–2.25)

 < 0.001

1.55 (1.14–2.10)

0.011

1.14 (0.79–1.65)

0.4811

 Frail versus fit

3.20 (2.56–4.13)

 < 0.001

2.41 (1.77–3.27)

 < 0.001

1.86 (1.36–2.52)

 < 0.001

Treatment limitation

 Vulnerable versus fit

2.26 (1.73–2.96)

 < 0.001

1.7 (1.21–2.38)

0.0021

  

 Frail versus fit

3.98 (3.08–5.21)

 < 0.001

2.79 (1.96–3.91)

 < 0.001

  

Mechanical ventilation

 Vulnerable versus fit

0.83 (0.67–1.01)

0.055

0.92 (0.73–1.16)

0.5

  

 Frail versus fit

0.75 (0.62–0.92)

0.005

0.69 (0.54–0.87)

0.0043

  

Non-invasive ventilation

 Vulnerable versus fit

1.58 (1.11–2.25)

0.011

1.22 (0.79–1.88)

0.37

  

 Frail versus fit

1.58 (1.12–2.24)

0.009

1.26 (0.8–1.95)

0.32

  

Non-invasive ventilation/mechanical ventilation

 Vulnerable versus fit

0.94 (0.78–1.13)

0.51

1 (0.81–1.24)

0.99

  

 Frail versus fit

0.84 (0.7–1.02)

0.069

0.74 (0.58–0.91)

0.0096

  

Vasoactive drugs

 Vulnerable versus fit

0.99 (0.81–1.22)

0.93

1.09 (0.86–1.39)

0.47

  

 Frail versus fit

1.01 (0.84–1.25)

0.88

0.9 (0.7–1.15)

0.44

  

Renal replacement therapy

 Vulnerable versus fit

1.23 (0.81–1.86)

0.33

1.14 (0.7–1.87)

0.61

  

 Frail versus fit

1.62 (1.1–2.45)

0.014

1.01 (0.59–1.65)

0.98

  
  1. First, we estimated the impact of frailty on outcome without adjustment on confounding using a baseline model including only frailty (model 1). Second, to estimate the impact of frailty when adjusting on patients’ baseline characteristics the following covariates were added to model 1: age, sex, comorbidities, SOFA score, BMI, PaO2/FiO2. Third, to evaluate whether the effect of frailty was independent of ICU management strategies, both organ support and treatment limitation (model 3) were added to model 2 as time-dependent covariates. For all outcomes, significance of the random centre effect was tested comparing the likelihood of two models including frailty with and without random effect. Random effect was significant for all outcomes. No violation of the proportional hazard assumption was detected in the models