Lung Function Reference Equations for Indian Ethnic Groups Based on a Handheld Forced Oscillation Device for Age 9–19 Years

Objective To develop regression equations to predict forced oscillation technique (FOT) parameters in Indian children and adolescents. Methods Lung function was assessed in a multigeographic cohort of residential school children using a portable FOT-based device (PulmoScan) and spirometry. FOT measurements were performed in 1497 study participants, aged 9–19 y, from 8 Indian districts. Bland–Altman analysis was performed for additional 32 adult subjects to compare the results of PulmoScan to a standard IOS device in an outpatient setting. Reference equations were developed for R rs and X rs from the data of healthy subjects with normal spirometry using multivariate regression model for Indo-European, Dravidian, and mixed ethnic groups. Results X5 (bias = 0.02) showed a better agreement than resistance parameters (R5 bias = 0.75, R20 bias = −0.22) in IOS/PulmoScan comparison. Anthropometric variables (age, height, and weight) were positively correlated with reactance (X5) and negatively with resistance parameters (R5, R10, R15, and R20), with most associations being stronger in boys. Final regression model considered ethnicity as a key determinant along with anthropometry. Conclusion Multiethnic reference equations were developed for Indian children aged 9–19 y based on a novel handheld FOT device.