Fibrinogen: A Feasible Biomarker in Identifying the Severity and Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background Chronic obstructive pulmonary disease (COPD) is no longer considered a disease exclusive to the respiratory system. It is a multipronged disease with both lung and systemic involvement. Although the forced expiratory volume (FEV) in one second is one of the most commonly used markers to assess disease severity, in recent years, biomarkers such as interleukin-1 beta, serum C-X-C motif chemokine ligand 10, fibrinogen, soluble receptor for advanced glycation, surfactant protein D, and club cell secretory protein have been proven to be effective markers to assess disease severity. Objective The current study aimed to test the association of fibrinogen levels with increased exacerbation of COPD per year and lower lung function and to discuss its potential utility as a biomarker. Methodology A total of 105 participants were enrolled in the study. The study participants included 35 stable COPD patients, 35 COPD patients with acute exacerbation, and 35 non-COPD healthy controls (matched for age and gender). All patients above 18 years of age who were diagnosed with COPD as per the Global Initiative for Chronic Obstructive Disease (GOLD) guidelines were considered for inclusion in the study. The patients were divided into stable COPD group and acute exacerbations of COPD (AECOPD) group based on the Anthonisen criteria. Sociodemographic factors, six-minute walk test, Medical Research Council Dyspnea Scale, and COPD Assessment Test scale were computed. Spirometry according to the American Thoracic Society guidelines and hematological investigations including serum fibrinogen were performed. Additionally, GOLD staging and severity indices were used to determine the clinical phenotyping of COPD, namely, ADO (age, dyspnea, airflow obstruction) index, BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, and DOSE (dyspnea, obstruction, smoking, exacerbation) index. Results Plasma fibrinogen level was significantly higher in the COPD groups compared to the control group. Plasma fibrinogen level was elevated in AECOPD compared to stable COPD patients. In addition, fibrinogen levels showed a positive correlation with important functional indices and prognostic markers such as BODE, ADO, and DOSE indices and a negative correlation with lung function. The odds of predicting an acute exacerbation of COPD for patients with FEV of <50% and FEV of >50% were 17.2 (area under the curve [AUC] = 0.825; sensitivity = 90.4%; specificity = 62.79%) and 15.1 (AUC = 0.791; sensitivity = 57.7%; specificity = 92.5%), respectively. Conclusions Plasma fibrinogen has the potential to be an important biomarker in the management of COPD and its exacerbation due to its ability to be responsive to the COPD disease statuses such as the severity of COPD and AECOPD.