Blood eosinophil count as a predictor of obstructive airway disease (OAD) in a high parasite burden setting

Abstract

Background: Eosinophilic inflammation is associated with OAD and has been reported to correlate with lower FEV1, faster decline in lung function and frequent exacerbations. Aims: To assess if eosinophil counts predict the presence of OAD in asymptomatic individuals. Methods: Spirometry and routine blood tests conducted as part of annual health screening at our institute were analyzed. OAD was defined as post bronchodilator FEV1/FVC 2% or absolute eosinophil count (AEC)>400/µl. Results: 561 patients were included (62% males, 12% smokers). Prevalence of OAD was 5.4%, of which 33% had significant bronchodilator reversibility. Of all the variables tested in a multivariate analysis (age, gender, smoking status and eosinophil count), only age and eosinophil counts were predictors of OAD (p 2%) and 152/561 (27%) had a high AEC (>400/µl). While high eosinophil count had low positive predictive value for OAD, eosinophil count Conclusion: Blood eosinophil count had a significant correlation to presence of OAD, but it did not predict bronchodilator reversibility. We found that a low eosinophil count was an excellent rule-out test for the absence of OAD. However, a high eosinophil count had poor specificity for the presence of OAD. This may be due to high parasite burden in our setting.