BAP 65 and DECAF scores in Predicting Outcomes in Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Prospective Observational Study

Abstract

Introduction: Chronic Obstructive Pulmonary Disease (COPD) is the fourth most common cause of mortality in the world. Acute Exacerbation of COPD (AECOPD) is a common entity to the emergency room of physician. It also contributes to the morbidity and mortality of the disease. Since multiple factors influence the outcomes of AECOPD, many prognostic indices incorporating various parameters have been proposed. BAP 65 {Blood Urea Nitrogen (BUN), Altered mental status, Pulse rate and age >65 years} and Dyspnoea grade, Eosinopenia, Consolidation, Acidemia and Atrial fibrillation (DECAF) are two which are commonly used. Head-to-head comparisons of these scores in their ability to correctly predict outcomes will aid the clinician in decision-making. Aim: To evaluate the performance of BAP 65 and DECAF scores in accurately predicting need for mechanical ventilation and mortality in patients with AECOPD. Materials and Methods: In this prospective observational study, 170 patients presenting with AECOPD to the emergency department were recruited consecutively. All patients were clinically examined and all variables for the calculation of the two scores were documented at baseline. Routine neurological examination was used to determine altered sensorium at admission. Following this, all patients underwent appropriate investigations including chest X-ray, Electrocardiogram (ECG) and arterial blood gas estimation. BAP 65 and DECAF scores were recorded and patients were followed till death or improvement. The results were analysed using Statistical Package for the Social Sciences (SPSS) software version 23. Student’s t-test, Mann-Whitney test and Chi-square test were used depending on the type of variables. Receiver Operating Characteristic (ROC) analysis was done and Area Under the Curve (AUC) was determined. A p-value <0.5 was deemed to be significant for all tests. Results: Out of 170 patients, 48 required non-invasive ventilation and 30 required invasive ventilation and 23 (13.5%) expired. Mortality correlated significantly with age, median years of COPD, smoking pack years and hospitalisations in the past one year and also with lower haemoglobin and higher total leucocyte counts and BUN values. Both BAP 65 and DECAF scores correlated with need for mechanical ventilation and mortality. Area Under Receiver Operator Characteristic Curves (AUROC) predicting mortality was 0.712 for BAP 65 and 0.965 for DECAF scores. AUROC predicting need for ventilation was 0.583 for BAP 65 and 0.791 for DECAF scores. DECAF showed sensitivity of 78.26%, specificity of 95.92%, Positive Predictive Value (PPV) of 75%, Negative Predictive Value (NPV) of 96.58%, with an accuracy of 87.09% in predicting mortality. In predicting need for mechanical ventilation, DECAF had sensitivity of 32.14%, specificity of 94.74%, PPV of 75%, NPV of 73.97% with an accuracy of 63.44%. DECAF showed a higher positive predictive value for both outcomes. Conclusion: History and basic clinical examination provide a lot of data to formulate prognosis in AECOPD. In resource-poor settings, BAP 65 can be used while DECAF can be used where arterial blood gas analysis is readily available, since both have proven to correlate with outcomes.