Factors affecting spirometry reference range in growing children

Area of Science:

• Pediatric Pulmonology
• Respiratory Physiology
• Biostatistics

Background:

• Spirometry is essential for assessing lung function in children and adolescents.
• Understanding the influence of anthropometric factors on spirometry is critical for accurate diagnosis and monitoring.
• Previous studies have explored these associations, but regional data, particularly from diverse urban populations like Karachi, is valuable.

Purpose of the Study:

• To investigate the correlation between weight, height, and age with key spirometry variables (FVC, FEV1, FEV1/FVC, PEF, FEF25-75) in children and adolescents.
• To develop regression equations for predicting spirometry values using weight, age, and height as independent variables.
• To establish normative data specific to the population of Karachi.

Main Methods:

• A modified International Study of Asthma and Allergies in Childhood (ISSAC) questionnaire was administered.
• Spirometry was performed to measure Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC ratio, Peak Expiratory Flow Rate (PEF), and Forced Expiratory Flow between 25% and 75% of expired volume (FEF25-75).
• Pearson correlation coefficients and linear regression models were employed to analyze the relationships between spirometry variables and anthropometric measurements (age, height, weight) in both boys and girls.

Main Results:

• A significant linear correlation (p-value < 0.000) was found between all spirometry variables and the independent variables of age, height, and weight.
• Age and height demonstrated a strong positive correlation with lung function parameters.
• Weight showed a moderately significant positive correlation with spirometry variables, indicating its influence on lung volumes.

Conclusions:

• Age, height, and weight are all significantly correlated with lung volumes and capacities measured by spirometry.
• These anthropometric factors must be considered when interpreting spirometry results in pediatric populations to ensure diagnostic accuracy.
• The findings support the inclusion of weight alongside age and height in regression equations for predicting normal spirometry values in children and adolescents.