International validation of "DECAF score" to predict disease severity and hospital mortality in acute exacerbation COPD in the United Arab Emirates

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. Acute exacerbation of COPD (AECOPD) is a concern due to its high mortality rate and negative outcomes in patient care. Therefore, tools that can predict the severity of the disease and inpatient mortality have gained much attention. In this regard, the Dyspnoea, Eosinopenia, Consolidation, Acidaemia, and Atrial Fibrillation (DECAF) score was adopted in many hospital settings for AECOPD patients in the United Kingdom because of its ease of use and effectiveness. However, less is known about its accuracy and association with patient clinical outcomes in worldwide healthcare systems, with no information available in the Middle East. Objectives: To validate the DECAF score for predicting inpatient death due to AECOPD and investigate whether the DECAF score can predict disease severity, hospital readmission, and length of hospital stay in a Middle Eastern healthcare setting. Furthermore, this study aimed to assess factors associated with inpatient death due to AECOPD. Methods: This was a retrospective observational study conducted between 2019 and 2021 in 19 hospitals in the United Arab Emirates. Data were retrieved from the electronic records of patients admitted for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in 17 hospitals across six Emirates. Patients who were diagnosed with AECOPD, aged over 35 years, were included in the study. There were three major primary outcomes for this thesis: 1) the validation of the DECAF Score for inpatient death, 30-day death, and 90-day readmission, 2) length of stay across DECAF scores, and 3) differences in the means of blood pH, eosinophils, C-reactive protein (CRP), and urea across patients with different DECAF scores. In addition to descriptive statistics, the validation of the DECAF score using the area under the receiver operator curve (AUROC) for inpatient death, 30-days death, and 90-day readmission was performed. The Hosmer-Lemeshow statistic and Nagelkerke statistic were used to assess the model fitness. The mean length of stay and laboratory markers (pH, eosinophil, CRP, and urea) across patients with different DECAF scores were compared using the ANOVA test, and p-values less than 0.05 were considered significant results. Error bar tests with 95% confidence intervals (CI) were used to measure differences in the 4 proportions of patients with atrial fibrillation and activity tolerance across the DECAF score. The Statistical Package for the Social Sciences (SPSS) version 26 was used for data analysis. Results: Of the 512 patients included in the study, 169 (33.0%) were females, and 64 (12.5%) were smokers. The mean (SD) age and length of stay in the hospital were 73.3 (11.9) years and 14.3 (32.5) days, respectively. The incidence of inpatient death and 90-day readmission was 24.4% and 35.9%, respectively. The median DECAF score was 3 [IQR: 1-6]. The top three comorbidities were hypertension (48.3%), diabetes (45.4%), and atrial fibrillation (45.2%). The AUROC DECAF curves for inpatient death, 30-days death, and 90-day readmission were 0.8 (95% CI: 0.8-0.9), 0.8 (95% CI: 0.7-0.8), and 0.8 (95% CI: 0.8-0.8), respectively. The model was a satisfactory fit to the data (Hosmer-Lemeshow statistic = 0.195, Nagelkerke R2 = 31.7%). There were significant differences in means of the length of stay across patients with different DECAF scores (p = 0.008). The highest mean (SD) length of stay in days was seen in patients with a DECAF score of 6, 29.8 (31.4), and the lowest value was reported in patients with a 0 DECAF score of 3.6 (2.0). There was no significant difference in serum albumin levels across patient death statuses. Additionally, BMI categories were not associated with inpatient death. Conclusion: The DECAF score shows strong predictive performance for the high levels of inpatient mortality, 30-day mortality, and 90-day readmission in the UAE setting. Additionally, the DECAF score can predict clinical parameters that can be helpful in clinical decision making. Keywords AECOPD, DECAF score, UAE, COPD