Systematic misclassification of lung function in Indian adolescents using GLI-2012 reference equations: evidence from the multicity APEAL cohort.

Authors

Priya Samdarshi, Padukudru Anand Mahesh, Swapnali Patil, Anant Mohan, George D'Souza, Rajesh Thimmulappa, Twinkle Agrawal, Jayaraj Biligere Siddaiah, Harish Chandra Phuleria

Published in

Thorax. Sep 22, 2026. Epub Sep 22, 2026.

Abstract

Accurate spirometric interpretation depends on appropriate reference equations. The Global Lung Function Initiative (GLI-2012) equations are widely used internationally, but South Asian populations were sparsely represented in their derivation and their applicability in Indian adolescents remains uncertain.
We performed a cross-sectional analysis of baseline data from the multicity Air Pollution Exposure on Adolescents' Lungs cohort. Healthy, non-smoking school-going adolescents aged 11-14 years from Delhi, Mumbai, Bengaluru and Mysuru underwent spirometry using standardised American Thoracic Society/European Respiratory Society procedures. GLI-2012 z-scores for forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC were calculated using the Asian reference category. Fit was assessed using mean z-scores and the proportion below the lower limit of normal (LLN; z<-1.645).
Among 4175 adolescents (2148 males), mean z-scores were -2.44 (SD 1.27) for FEV₁, -1.34 (0.93) for FVC and -0.78 (1.11) for FEV₁/FVC, all well outside the accepted ±0.5 range for adequate fit. Overall, 74.6% were below the LLN for FEV₁, 36.8% for FVC and 19.3% for FEV₁/FVC, compared with the expected 5% in a well-calibrated healthy population. The leftward shift in z-score distributions was consistent across sex, city, age, height and body mass index strata.
GLI-2012 equations, as currently applied in the absence of South Asian-specific references, demonstrated substantial calibration mismatch relative to this cohort of Indian adolescents and risk major overclassification of low lung function. Population-specific validation and recalibration are needed before routine clinical or epidemiological use in this population.

PMID:
42772898
Bibliographic data and abstract were imported from PubMed on 23 Sep 2026.

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