Figure 4.

Decision curve analysis (DCA) for prediction of successful extubation (ES; n=530). The net benefit (NB) of the updated CART model and single predictors is plotted against the threshold probability (Pt); patients with predicted probability of ES above the threshold are classified as positive. The zero reference line (extubation in none) represents the strategy of assuming all patients will fail the extubation and thus extubating none of them, whilst the line labeled current strategy represents the extubation of all patients having successfully passed the SBT if neurological status, excessive secretions, adequate cough and airway obstruction were not issues. ∆NB is the difference in net benefit between a specific model (or a specified single predictor) and the current strategy at a single Pt. SBT, spontaneous breathing trial; CART, classification and regression tree; RSBI₃₀, rapid shallow breathing index at 30 min of SBT; ∆RSBI₃₀, change in RSBI at 30 min of SBT, expressed as a percentage of RSBI₃₀ to RSBI₁.