Impact of frailty and older age on weaning from invasive ventilation: a secondary analysis of the WEAN SAFE study

Objective: To understand the impact of both frailty and chronologic age on outcomes of weaning from invasive mechanical ventilation (MV). Methods: The study population consisted of patients enrolled in the ‘WorldwidE. AssessmeNt of Separation of pAtients From ventilatory assistancE (WEAN SAFE) study. We defined 4 non-overlapping groups, namely: ‘frail’ (clinical frailty scale [CFS] score > 4; age < 80 years); ‘elderly’ (CFS ≤ 4; age ≥ 80y), ‘frail \elderly’ (CFS > 4; age ≥ 80 years), and a ‘not frail or elderly’ population. The primary outcome was the impact of frailty and older age on delayed weaning and failed weaning from invasive MV. Secondary outcomes included the impact of frailty and age on ICU and hospital survival. Results: In the study population, 760 (17%) were frail, while 360 (8%) were elderly, 197 (4%) were frail and elderly, while 3,176 (70%) were not frail or elderly. The frail and elderly cohorts were more likely to be female, had hypoxemic/hypercapnic respiratory failure or sepsis, and had more comorbidities. The proportion of delayed weaning and of failed weaning from invasive MV was significantly higher in the frail (28 and 23%), the elderly (25 and 19%), and the frail and elderly groups (22% and 25%), compared to the not frail or elderly population (12% and 13%, P < 0.01). ICU and hospital mortality was higher in the frail (21 and 33%), the elderly (19 and 31%), and the frail and elderly groups (26 and 46%), compared to the not frail or elderly population (12% and 18%, P < 0.001). In multivariate analyses, there was an independent association between frailty and delayed weaning initiation and weaning failure. Old age was independently associated with risk of weaning failure. Conclusions: Frailty status had a more consistent impact than older age on weaning outcomes. However, overall outcomes in these cohorts are encouraging once separation attempts have been initiated.