Association between serum interleukin- 6 concentrations, chronic obstructive pulmonary disease, and its relation to severity, acute exacerbation, and its effect on pulmonary function test

Abstract Background The main reason for the severity of COPD is an exacerbation. Patients with COPD who experience repeated infectious exacerbations have higher rates of morbidity and increased death. The purpose of this study is to determine how blood interleukin- 6 levels affect pulmonary function tests and how these levels relate to the severity and acute exacerbation of COPD. Methods A cross-sectional case–control observational study included 200 participants. One-hundred participants were diagnosed with acute exacerbations of COPD, and 100 healthy participants served as a control group. Clinical examinations, including anthropometric measures (height, weight, and the calculated BMI), number of exacerbations, and hospitalizations in the prior year, chest radiography, spirometry before and after bronchodilator, and laboratory tests including complete blood count (CBC), ESR, C-reactive protein (CRP), and interleukin- 6 (IL6) were done. Results CRP, IL- 6, hemoglobin, and all spirometry parameters showed significant differences between the two groups ( P < 0.001), serum IL- 6 and CRP levels, the number of exacerbations during the past year, and spirometry data (FEV1, FEV1/FVC ratio) all showed significant correlations. Multiple linear regression showed that IL- 6 was the most potent predictor, followed by the smoking pack-years index, CRP, and hemoglobin. The IL- 6 level predicts the frequency of exacerbations each year with remarkable accuracy in ROC curve. Conclusion IL- 6 levels are elevated in COPD patients as a part of systemic inflammation and are strongly associated with the severity of the disease. IL- 6 level of 13 pg/mL or higher is a powerful predictor for COPD exacerbations ≥ 2/year.