MATERIAL AND METHOD
A cross-sectional study with an analytical component was carried out, without direct intervention on the study subjects.
The study population was children aged 5 to 15 years with clinical suspicion of asthma, who underwent spirometry and MT or ET within a period of 60 days, in the pulmonary function laboratory of Clínica INDISA, from January 2017 to December 2019.
Spirometry was performed according to national and international standards, with an MGC Diagnostics ® equipment, and only those that met the acceptability and reproducibility criteria were included(12,13). Multiethnic reference values were used for their interpretation (14). The MT was carried out with the technique of increasing concentrations of Cockcroft and the PC20(5,15) was determined. The ET was performed on a treadmill at submaximal heart rate, with humidity and environmental temperature control, with subsequent measurement of the percentages of fall in FEV1 with respect to baseline at 3, 5, 10, and 15 minutes post-exercise (16).
We worked on an anonymized database, which identified each child with a number (ID), age (in years, months) and if he was using inhaled corticosteroids at the time of the exam, height, weight, clinical diagnosis, and date performance of spirometry, MT and TE. The lower limit (LI) and Zscore of FEV1, FEV1/FVC, FVC, FEF25-75, % change with the bronchodilator in FEV1, FEF25-75 and FVC were recorded from the spirometries. The PC20 and the percentage of maximum drop in FEV1 in the ET were verified.
All these data from the reports of these tests appear in the manual and computerized records of the Clínica INDISA lung function laboratory.
Children who obtained a bronchodilator response (BDR) ≥ 30% in FEF25-75 (SBDR) were compared versus those who obtained a BDR < 30% with normal FEV1, FEV1/FVC, in relation to the MT and ET in each patient.
The STATA 14.0 statistical package and Microsoft Excel 2016 software were used for data analysis. A descriptive analysis of the variables of interest was made and Chi-square tests were used to analyze the groups in relation to their results in the MT and ET. A p value less than 0.05 was considered statistically significant.
To carry out this project, authorization was obtained from the Medical Directory of the Clínica INDISA and the approval of the Bioethics Committee of the Andrés Bello University.