Reference equations for evaluation of spirometry function tests in South Asia, and among South Asians living in other countries

Abstract

BackgroundThere is little data to accurate interpretation of spirometry data in South Asia, a major global region with high reported burden for chronic respiratory disease.MethodWe measured lung function in 7,453 healthy men and women aged over 18 years, from Bangladesh, North India, South India, Pakistan and Sri Lanka, as part of the South Asia Biobank study. We first assessed the accuracy of existing equations for predicting normal forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC ratio. We then used our data to derive (N=5589) and internally validate (N=1864) new prediction equations amongst South Asians, with further external validation amongst 339 healthy South Asians living in Singapore.ResultsGLI2012 and NHANESIII consistently overestimated expiratory volumes (best fit GLI-African American, mean [sd] z-score (n=7453): FEV1 −0.94 [1.05]; FVC −0.91 [1.10]). Age, height and weight were strong predictors of lung function in our participants (p<0.001), and sex specific reference equations using these three variables were highly accurate in both internal validation (z-scores: FEV1 0.03 [0.99]; FVC 0.04 [0.97]; FEV1/FVC −0.03 [0.99]) and external validation (z-scores: FEV1 0.31 [0.99]; FVC 0.24 [0.97]; FEV1/FVC 0.16 [0.91]). Further adjustment for study regions improves the model fit, with highest accuracy for estimation of region specific lung function in South Asia.ConclusionWe present improved equations for predicting lung function in South Asians. These offer the opportunity to enhance diagnosis and management of acute and chronic lung diseases in this major global population.

Spirometric Interpretation and Clinical Relevance According to Different Reference Equations

“… 3 A recent study suggested higher accuracy when the information on region was added to the lung function reference equation. 26 In fact, our study showed considerable discrepancy in the predictive value of FEV 1 or COPD severity between global reference equation (GLI-2012) and region-specific reference equations (Choi’s and KHANES VI). One of the potential reasons for the discrepancy may be attributed to variations in human body proportions based on different ethnicities of GLI-2012 reference equation.…”

Design and Development of an IoT-based Pulmonary Function and Oxygen Saturation Measurement Device

“…In detecting the presence of bronchial asthma, health workers usually use a spirometer by measuring the volume in the FVC and FEV1 examinations [7] [8]. However, In providing services to patients with bronchial asthma not only requires this measurement alone as the only diagnostic tool, but health care providers need time to access to spirometer data and then follow up on symptoms and treatment schedules [9] [10].…”

Letter from Singapore

“…4 Other key cohorts include the Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO), the Singapore-Malaysia Cross Sectional Genetic Epidemiology Study (SMCGES) and the Health for Life in Singapore (HELIOS) study that have contributed to developing spirometry reference equations for South Asians and, demonstrated the additive climatic influence (beyond familial tendency) on risks of developing allergy, asthma and allergic rhinitis in our tropical climate. 5,6 With the ongoing transformational shift in national population health delivery through Healthier SG, the focus on preventative and proactive care needs to leverage on these established cohorts especially once chronic respiratory conditions such as asthma and COPD come onboard next year (2024). 7 A local lung cancer study demonstrated that many females and non-smokers diagnosed with lung cancer did not fit US National Lung Screening Trial criteria, a finding observed across other Asia Pacific countries.…”