Derivation of a prognostic equation to predict in-hospital mortality and requirement of invasive mechanical ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease.

ABSTRACT

OBJECTIVE: Predicting in-hospital mortality and formulating a scoring system derived from predictors of mortality may aid prognostication. METHODS: One hundred and fifty-one consecutive patients admitted with a diagnosis of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) were followed to discharge or death in hospital stay. Secondary variables studied were duration of hospital stay, and need for and duration of mechanical ventilation (MV). RESULTS: Mean (SD) age of patients was 60.5 (11.4) years; 65.6% were mechanically ventilated, and 25.2% died in hospital. Independent predictors of mortality at admission were serum creatinine (odds ratio [OR] 2.1, 95% Confidence intervals [CI] 1.03 to 4.30; p = 0.04), and serum sodium (OR 0.94, 95% CI 0.90 to 0.99; p = 0.03). An equation derived [Score = 8+ (0.74 x creatinine) = (0.015 x sodium)] to predict mortality, had an area under receiver operating characteristic (ROC) curve of 73%, with a cut-off of 6.74 having sensitivity, specificity, positive and negative predictive values for predicting death of 71%, 64%, 40% and 87%, respectively. Glasgow coma scale (GCS), partial pressure of oxygen in arterial blood (PaO2) and partial pressure of carbon dioxide in arterial blood (PaCO2) at admission independently predicted need for invasive ventilation. An equation derived [Score = 2.36+(0.02 x PaO2)+(0.05 x PaCO2)-(0.47 x GCS)] to predict need for MV, had an area under ROC curve of 85%, with a cut-off of 0.54 having sensitivity, specificity, positive and negative predictive values for predicting need for MV of 82%, 81%, 89% and 70%, respectively. CONCLUSIONS: Serum creatinine and sodium at admission are independent predictors of mortality for patients admitted with AECOPD. The equation derived from these two variables is a simple and useful method for predicting outcome.