To the Editor: This cohort study was carried on children aged 5–18 y, with persistent asthma and those who received inhaled corticosteroids (ICS) for 4 wk; children unable to induce sputum and those with inadequate sputum sample were excluded. At baseline and at 6 mo, sputum smear examination and spirometry were done. Sputum inflammatory phenotype were classified by presences of eosinophils and neutrophils [1]. The response to therapy was assessed by GINA levels of asthma symptom control and children were treated as per GINA guidelines 2020. One hundred and one children satisfied the inclusion criteria; 54 children (at baseline) and 44 children (at 6 mo) showed inflammatory cells in sputum smear. Sixteen (29.6%) children had a family history of asthma and 23 (42.5%) had allergic rhinitis. The median (IQR) of IgE was 209 (85, 258) and eosinophilic, neutrophilic, mixed-granulocytic and pauci-granulocytic phenotypes were 40 (74%), 8 (14.8%), 4 (7.4%) and 2 (3.7%) respectively at baselines. Acute (baseline) and controlled (at 6 mo) persistent asthmatic children showed 40 (74%) and 23 (71.8%) eosinophilic phenotype. Twelve (27.2%) uncontrolled asthmatic children demonstrated phenotypic variation at 6 mo and mixed-granulocytic phenotype accounted 50%. Eosinophil percentages were significantly reduced at 6 mo (p = 0.002). The asthma control between eosinophilic and non-eosinophilic asthma was similar (p = 0.2) and spirometry showed significant improvement at 6 mo (p <0.05).

We demonstrated similar four sputum inflammatory phenotypes in Indian children [1, 2]. Different immunopathological mechanisms may have similar airway inflammation in the same child over time [3] or airway inflammation is subjected to change during exacerbation [4]. Similarly, we have also found eosinophilic phenotypes in acute and controlled persistent asthmatic children and phenotypic variation among same children during exacerbation at 6 mo. ICS can lead to reduced eosinophil count as demonstrated in the present study [2]. The asthma control was not related to sputum inflammatory phenotypes but spirometry can have a better correlation. Therefore, routine sputum cytology has a limited role in children.