A new tool for predicting in-hospital mortality in Chinese older patients with exacerbation of chronic obstructive pulmonary disease(AECOPD): frailty index based on common laboratory tests (FI-Lab)

Abstract

Introduction: The exacerbation of chronic obstructive pulmonary disease(AECOPD)is a common and fetal disease but with no ideal predictor of in-hospital mortality. Frailty prevails in older adults with AECOPD and can cause increased vulnerability to many adverse health outcomes including death. However, we know little about how frailty affects in-hospital mortality in older AECOPD patients. Objective: To explore the predictive validity of FI-Lab—an objective tool for assessing frailty including 21 routine blood tests plus systolic and diastolic blood pressure (a score between 0 and 1, a higher score indicates greater frailty)—for in-hospital mortality in patients with AECOPD. Methods: We reviewed the hospitalization records of older AECOPD inpatients from September 2016 to June 2019 at Zhenjiang First People's Hospital. We compared survivors to non-survivors. We used propensity score matching (PSM) to balance priori differences between survivors and non-survivors. Logistic regression analysis was used to select the associated predictors of in-hospital mortality. Receiver-operating characteristic (ROC) curves were calculated to estimate the area under the ROC curve (AUCs) for FI-Lab and DECAF(a commonly used predictor of AECOPD including dyspnea, eosinophilia, pulmonary consolidation, acidemia, and atrial fibrillation; a score between 1and 6; a higher score indicates poorer condition)in relation to mortality. Data were analyzed using IBM SPSS for Windows, Version 23.0. Results: A total of 154 patients—77 survivors and 77 non-survivors—were included in the study finally. The mean age of these patients was 79.73 ± 8.38 years. Both of the mean DECAF score, the mean FI-Lab value of non-survivors were statistically higher than those of survivors(4.45 ± 0.80 versus 3.03 ± 0.90,P = 0.000; 0.51 ± 0.13 versus 0.29 ± 0.10,P = 0.000,respectively). Logistic regression analysis suggested that high DECAF grade and high FI-Lab grade were strong related factors of death in AECOPD patients (OR:5.620, 95%CI 2.811–11.236, P = 0.000; OR:8.705, 95%CI 3.646–20.782, P = 0.000, respectively). The DECAF scores of most non-survivors were ≥ 4༈n = 71,92.21%༉. FI-Lab value predicted in-hospital mortality at a cut-off value of 0.4388 with 70.1% sensitivity, 96.1% specificity, 0.675 Youden index. DECAF score predicted in-hospital mortality at a cut-off value of 3.5 with 92.2% sensitivity, 72.7% specificity, 0.649 Youden index. The areas under the ROC curves were 0.906 for FI-Lab and 0.870 for DECAF with no statistically significant༈P = 0.2991). Conclusions: FI-Lab has a slightly stronger screening ability than DECAF. FI-Lab is a simple, effective and objective indicator and can be quick to help clinicians to assess in-hospital mortality of AECOPD patients.