RESULTS
From April 2018 to March 2020, seventy-nine asthmatic patients underwent the induction of sputum. No patient had to interrupt the collection due to adverse events (dyspnea, wheezing, or change in peak expiratory flow rate). Thirty-three cases were excluded due to sputum sample inadequacy that resulted in 46 patients completely studied of whom 27/46 (58.7%) were male and 19 (41.3%) were female. The mean age was 9.4 (±3) years.
Asthma was severe in 29 (63.1%) and moderate in 17 (36.9%) patients. No patient was classified as having mild asthma. Thirty-nine (84.7%) patients were on regular inhaled steroids. ACT showed that 25 (56.8%) children had controlled disease.
The mean age at the first asthma attack was 3.2 (± 3.3) years, and 12 (26%) children presented the crisis before the first year of life. In addition, 44 (95.6%) patients had already needed emergency department visit at least once, 17 (36.9%) needed hospitalization and five (10.8%) needed admission to intensive care unit. The most common allergic comorbidity was rhinitis, observed in 44 (95.6%) patients, followed by conjunctivitis in 13 (28.2%) and atopic dermatitis in 11 (23.9%) patients. Family history of asthma was present in 30 (65.7%) patients, and 16 (34.7%) lived with smoker at home.
Allergy skin tests performed in 41 (89.1%) patients were positive in 35 (85.4%), in 24 (68.5%) for only one inhalant allergen (mono-sensitization). Sensitization to mites predominated and was present in all tested patients.
The median total serum IgE levels was 797 IU/mL (0–9,411) and considered elevated in 29/35 (82.8%) patients. The median blood eosinophil count was 505 × 10³/uL (0–2,094) and abnormally elevated in 24/36 (66.6%).
Spirometry was performed in 45 children (97.8%), and 13 (28.9%) showed obstructive ventilatory defect. The bronchodilator response was positive in 19 (42.2%) patients. Table 1 shows the characteristics of the study sample.
A predominance of eosinophilic pattern has been found in induced-sputum (25/46, 54.3%), followed by mixed (13/46 - 28.3%), pauci-granulocytic (7/46 - 15.2%), and neutrophilic (1/46, 2.2%) patterns.
There was no statistically significant correlation between the four cytological profiles and clinical, laboratory, and functional variables. However, if samples were sub-grouped in eosinophilic (eosinophilic and mixed) and non-eosinophilic (neutrophilic and pauci-granulocytic) patterns, there was an association between elevated blood eosinophils and the sputum eosinophilic pattern (p = 0.02). Table 2.