Dear Editor,
In response to the editor's letter criticizing our recently published work,1 we would like to clarify the following points. Our study investigated intrathoracic oscillations' effects on pulmonary function in children with spastic quadriplegic cerebral palsy. In the literature, the majority of the published research that studied the effect of specific treatment on respiratory function with similar objectives as our published work did not use predictive equations.2, 3, 4
We would like to point out that the stated references in the letter to the editor follow a different research objective than ours. The study by Sadiq et al.,5 aimed to discover the relationship between weight, height, and age with spirometry variables and to generate a regression equation using weight as an independent variable alongside age and height among children and adolescents from Karachi. The study by Chang et al.,6 aimed to establish reference equations for spirometry in healthy Taiwanese children and to assess the applicability of the Global Lung Function Initiative (GLI) 2012 equations to Taiwanese children. The study by Jones et al.,7 aimed to generate spirometry reference values in Brazilian children aged 3–12 years old and compare those values to the values used in the equations currently in use in Brazil. The study by Kim et al.,8 aimed to determine the reference values that would apply to Korean children and adolescents. Based on the stated references, the formulation of predictive respiratory equations is to compare the respiratory function with a normal reference. This is completely different from our study's objective, which compares statistically each child's results before and after treatment. Furthermore, Parker9 mentioned clearly that “Spirometry is useful to detect and monitor airway disease in patients with symptoms, risk factors, or suspicion of airway disease. Spirometric equipment is readily available and requires little maintenance and some calibration.” Therefore, there is no necessity to use predictive respiratory equations in studies using spirometry in the assessment of respiratory functions after treatment.
Source of funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflict of interest
The authors have no conflict of interest to declare.
Ethical approval
Not applicable.
Author's contributions
The project was developed and designed by AME and MEA, who also performed the research, gathered, categorised, and processed the data. Research resources were offered by AME. MEA wrote the article's first and last drafts. All authors have critically reviewed and approved the final draft and are responsible for the content and similarity index of the manuscript.
Footnotes
Peer review under responsibility of Taibah University.
References
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