External validation of prognostic model of one-year mortality in patients requiring prolonged mechanical ventilation

External validation of prognostic model for one-year mortality in patients ventilated for 21 days or more. A measure that identifies patients who are at high risk of mortality after prolonged ventilation will help physicians communicate prognoses to patients or surrogate decision makers. Our objective was to validate a prognostic model developed by Carson et al in a different setting.

An observational study was conducted from September 2002 to September 2007 in 30 beds Medical/Surgical Intensive Care Unit (ICU) at Mercy Fitzgerald Hospital (MFH) and 20 beds Medical/Surgical ICU at Mercy Philadelphia Hospital (MPH). One hundred and fifty medical and surgical patients requiring mechanical ventilation after acute illness for at least 21 days after initial intubation were enrolled.

One year mortality was 45.4%. Area under the receiver operating characteristic curve for three month mortality was 0.90 and for one year mortality was 0.92. For identifying patients who had ≥90% risk of death at 3 month had sensitivity of 40% and specificity of 95% and risk of death at 1 year had sensitivity of 70% and specificity of 99%. Four predictive variables, requirement of vasopressors, hemodalysis, platelet count ≤ 150 x 10 9/L and age ≥50 yrs can be used as a simple prognostic score that clearly identifies low-risk patients and high-risk patients.

Simple clinical variables measured on day 21 of mechanical ventilation can identify patients at highest and lowest risk of death from prolonged mechanical ventilation.