Spirometry reference ranges for children/adolescents of Karachi

摘要

Background: Accurate diagnosis of respiratory disease requires region specific reference range. The objective of this study was to establish spirometry reference ranges for children and adolescents of Karachi, considering height as an independent variable. Method: This was a cross-sectional study conducted from Apr to Oct 2017. A questionnaire was referenced from the International Study of Asthma and Allergies in Childhood (ISAAC). Spirometry variables taken were Forced Vital Capacity (FVC), Forced Expiratory Volume in 1st second (FEV1), FEV1/FVC ratio, Peak Expiratory Flow Rate (PEF), Forced Expiratory Flow between 25% and 75% expired volume (FEF25–75). The reference values were established using normal distribution curve; Mean±2SD was taken as significant. The linear regression models were calculated for all pulmonary variables with the age and height. Data with p0.05 was considered as statistically significant. Results: The FVC, FEV1, FEV1/FVC, PEF and FEF25–75 were 2.21±0.75 L, 2.08±0.73 L, 92.9±4.7%, 231.3±70.5 L/min and 2.68±1.2 L/Sec, respectively. The lung volumes were directly increasing with height from children to adolescents. There was a strong positive correlation between height and pulmonary variables, including FVC, FEV1, PEF and FEF25–75. Conclusion: The current study establishes a normative reference range along with a prediction equation for children and adolescents of age group 7–18 years of Karachi. There was a strong positive correlation of height with the spirometry variables.