Correlation of total serum immunoglobulin E level, sputum, and peripheral eosinophil count in assessing the clinical severity in bronchial asthma

CONTEXT Asthma is a chronic inflammatory disorder of the airway with involvement of various cellular populations and release of many inflammatory mediators. Eosinophils and serum immunoglobulin E (IgE) are considered a good marker of airway inflammation in asthma. The correlation of clinical assessment with various markers of airway inflammation in asthma is not well established in the Indian population. AIMS This study aims to study the correlation of serum IgE, sputum eosinophil count, and peripheral eosinophil count with clinical severity of Asthma. METHODS This is a cross-sectional study involving 76 stable asthmatic patients of 18-60 years of age attending the pulmonary medicine OPD. Spirometry measured at baseline. Participants were categorized according to the GINA criteria based on clinical symptoms and pulmonary function test. Blood samples were collected for peripheral eosinophil count, serum IgE levels, and sputum samples for eosinophil count. All three parameters were compared with severity of asthma. The correlation of sputum eosinophil count, peripheral eosinophil count, and serum IgE with severity of asthma was analyzed by Pearson's Chi-square test, Fisher's exact test, and the correlation coefficient was reported together with standard error of the estimate. RESULTS The mean age of patients in our study was 37.42 years and 56.6% were male. There was a significant inverse correlation between serum IgE levels and predicted forced expiratory volume 1 s (FEV1). Sputum eosinophilia was significantly seen in severe persistent asthma patients (19.7%). There was a significant inverse correlation between sputum eosinophil count and predicted FEV1and forced vital capacity. We also found there was a significant association between peripheral eosinophil count, sputum eosinophil count, and elevated serum IgE (g100 IU/mL) with severe persistent asthma. CONCLUSIONS The assessment of sputum eosinophil count is simple, inexpensive, noninvasive, and direct measurement of airway inflammation. It could be the preferred method in monitoring airway inflammation and guided management in day-to-day practice.