Comparison of pulmonary function in immigrant vs US-born Asian Indians

Comparison of race-specific and race-neutral GLI spirometric reference equations with an Indian reference equation

BACKGROUND

Despite the increasing popularity and use of Global Lung Function Initiative (GLI) spirometric reference equations, the appropriateness of the race-specific and race-neutral GLI spirometric reference models among the Indian population has not been systematically investigated.

METHODS

In this cross-sectional analysis, we used spirometric measurements of 1123 healthy Indian adults (≥18 years of age). We computed reference values and z-scores for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC from race-specific and race-neutral GLI reference equations as well as from a widely used Indian reference equation. We studied heterogeneity between GLI equations and the Indian equations using Bland-Altman analysis, and the differences between the reference and observed values were compared using the Friedman test.

RESULTS

In Bland-Altman analysis, significant heterogeneity in FVC and FEV1 between race-specific and Indian equations was observed (bias: 10.4 % and 14.1 %, respectively), with less bias for FEV1/FVC (3.76 %). The race-neutral equations showed almost similar bias (9.8 %, 13.8 %, and 3.8 % for FVC, FEV1, and FEV1/FVC, respectively). Median differences in race-specific reference values from observed values for FVC and FEV1 were 0.49L and 0.44L, respectively, decreasing slightly with race-neutral equations (0.46L and 0.43L) whereas Indian models showed minimal differences (FVC: 0.10L, FEV1: 0.05L). Z-scores for FVC and FEV1 were significantly different between race-specific and race-neutral GLI equations, and both differed from Indian equations.

CONCLUSION

Both race-specific and race-neutral GLI reference equations are significantly different from the Indian equations, which underscores the importance of determining the suitability of global reference models before being used indiscriminately.

Changes in interpretation of spirometry by implementing the GLI 2012 reference equations: impact on patients tested in a hospital-based PFT lab in a large metropolitan city

BACKGROUND

The Global Lung Function Initiative (GLI-2012) focused on race/ethnicity as an important factor in determining reference values. This study evaluated the effects of changing from Canadian reference equations developed from an all-Caucasian cohort with European ancestry to the GLI-2012 on the interpretation of spirometry in a multiethnic population and aimed to identify the ethnic groups affected by discrepant interpretations.

METHODS

Clinically indicated spirometry in a multiethnic population (aged 20-80 years) collected from 2018 to 2021 was analysed. The predicted and lower limit of normal (LLN) values were calculated using three sets of reference equations: Canadian, GLI-race/ethnic-based (GLI-Race) and GLI-race/ethnic-neutral (GLI-Other). We compared the prevalence of concordance in the abnormal diagnoses (defined as <LLN) for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC among the three reference values, and evaluated whether race/ethnicity was associated with discordance.

RESULTS

Data from 406 participants were evaluated (non-Caucasian 43.6%). There was 85%-87% concordance for normal/abnormal FVC and FEV₁ interpretations among the Canadian, GLI-Race and GLI-Other reference equations. In all ethnic groups, application of the Canadian references for interpretation led to a higher prevalence of abnormal (<LLN) FVC and FEV₁compared with GLI-Race and GLI-Other. This trend was more prominent in Black, South-East Asian and Mixed/other ethnic groups when comparing the Canadian to the GLI-Race equations. In contrast, the discordance rates were similar among ethnic groups when compared with the GLI-Other reference equations. Interpretation of FEV₁/FVC had a high rate of agreement among all equations.

CONCLUSION

Interpretation using Canadian reference equations was associated with a higher prevalence of restrictive physiology compared with the GLI-2012 equations, particularly if the GLI-Race were used. These observations were mostly found in non-white Caucasian groups, highlighting the need to choose reference equations that reflect closely the ethnic mix of the population being evaluated in order to optimise patient management.

Spirometry reference equations for children from a Middle Eastern population

BACKGROUND

Spirometry is a clinically useful test that can be used to assess lung function among children. Different equations had been formulated to determine the spirometric reference values depending on several individual characteristics. However, the widely used equations do not produce perfect suitability for Middle Eastern children.

OBJECTIVES

This study aims to formulate Middle Eastern-specific equations that may be applicable for other populations in the region.

METHODS

The spirometric data were collected from Jordanian children between the ages of 6 and 17 years. The collected data were used to formulate customised reference equations for Middle Eastern children using generalised additive models for location, scale and shape. The newly formulated equation results were compared with Global Lung Initiative 2012 (GLI-2012) equations predicted values.

RESULTS

Spirometric values for 1576 healthy participants (870 males) were used to formulate the new equations. The assessment of z-scores produced by the present study equations and GLI-2012 indicated that the new equations were more suitable than GLI-2012 for Middle Eastern children. In-depth analysis of the results indicated that the suitability of GLI-2012 equations varied between different age points.

CONCLUSION

This study formulated new spirometric reference equations for Middle Eastern children that can improve the diagnosis and management of different respiratory conditions.

Addressing Race in Pulmonary Function Testing by Aligning Intent and Evidence With Practice and Perception

The practice of using race or ethnicity in medicine to explain differences between individuals is being called into question because it may contribute to biased medical care and research that perpetuates health disparities and structural racism. A commonly cited example is the use of race or ethnicity in the interpretation of pulmonary function test (PFT) results, yet the perspectives of practicing pulmonologists and physiologists are missing from this discussion. This discussion has global relevance for increasingly multicultural communities in which the range of values that represent normal lung function is uncertain. We review the underlying sources of differences in lung function, including those that may be captured by race or ethnicity, and demonstrate how the current practice of PFT measurement and interpretation is imperfect in its ability to describe accurately the relationship between function and health outcomes. We summarize the arguments against using race-specific equations as well as address concerns about removing race from the interpretation of PFT results. Further, we outline knowledge gaps and critical questions that need to be answered to change the current approach of including race or ethnicity in PFT results interpretation thoughtfully. Finally, we propose changes in interpretation strategies and future research to reduce health disparities.

Applying Integrated Exposure-Response Functions to PM2.5 Pollution in India

Fine particulate matter (PM2.5, diameter ≤2.5 μm) is implicated as the most health-damaging air pollutant. Large cohort studies of chronic exposure to PM2.5 and mortality risk are largely confined to areas with low to moderate ambient PM2.5 concentrations and posit log-linear exposure-response functions. However, levels of PM2.5 in developing countries such as India are typically much higher, causing unknown health effects. Integrated exposure-response functions for high PM2.5 exposures encompassing risk estimates from ambient air, secondhand smoke, and active smoking exposures have been posited. We apply these functions to estimate the future cause-specific mortality risks associated with population-weighted ambient PM2.5 exposures in India in 2030 using Greenhouse Gas-Air Pollution Interactions and Synergies (GAINS) model projections. The loss in statistical life expectancy (SLE) is calculated based on risk estimates and baseline mortality rates. Losses in SLE are aggregated and weighted using national age-adjusted, cause-specific mortality rates. 2030 PM2.5 pollution in India reaches an annual mean of 74 μg/m³, nearly eight times the corresponding World Health Organization air quality guideline. The national average loss in SLE is 32.5 months (95% Confidence Interval (CI): 29.7⁻35.2, regional range: 8.5⁻42.0), compared to an average of 53.7 months (95% CI: 46.3⁻61.1) using methods currently applied in GAINS. Results indicate wide regional variation in health impacts, and these methods may still underestimate the total health burden caused by PM2.5 exposures due to model assumptions on minimum age thresholds of pollution effects and a limited subset of health endpoints analyzed. Application of the revised exposure-response functions suggests that the most polluted areas in India will reap major health benefits only with substantial improvements in air quality.

Development of Ahmedabad's Air Information and Response (AIR) Plan to Protect Public Health

Indian cities struggle with some of the highest ambient air pollution levels in the world. While national efforts are building momentum towards concerted action to reduce air pollution, individual cities are taking action on this challenge to protect communities from the many health problems caused by this harmful environmental exposure. In 2017, the city of Ahmedabad launched a regional air pollution monitoring and risk communication project, the Air Information and Response (AIR) Plan. The centerpiece of the plan is an air quality index developed by the Indian Institute of Tropical Meteorology’s System for Air Quality and Weather Forecasting and Research program that summarizes information from 10 new continuous air pollution monitoring stations in the region, each reporting data that can help people avoid harmful exposures and inform policy strategies to achieve cleaner air. This paper focuses on the motivation, development, and implementation of Ahmedabad’s AIR Plan. The project is discussed in terms of its collaborative roots, public health purpose in addressing the grave threat of air pollution (particularly to vulnerable groups), technical aspects in deploying air monitoring technology, and broader goals for the dissemination of an air quality index linked to specific health messages and suggested actions to reduce harmful exposures. The city of Ahmedabad is among the first cities in India where city leaders, state government, and civil society are proactively working together to address the country’s air pollution challenge with a focus on public health. The lessons learned from the development of the AIR Plan serve as a template for other cities aiming to address the heavy burden of air pollution on public health. Effective working relationships are vital since they form the foundation for long-term success and useful knowledge sharing beyond a single city.

Global lung function initiative 2012 reference values for spirometry in Asian Americans

Background

Spirometry reference values specifically designed for Asian Americans are currently unavailable. The performance of Global Lung Function Initiative 2012 (GLI-2012) equations on assessing spirometry in Asian Americans has not been evaluated. This study aimed to assess the fitness of relevant GLI-2012 equations for spirometry in Asian Americans.

Methods

Asian subjects who never smoked and had qualified spirometry data were extracted from the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Z-scores of forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and FEV₁/FVC were separately constructed with GLI-2012 equations for North East (NE) Asians, South East (SE) Asians, and individuals of mixed ethnic origin (Mixed). In addition, Proportions of subjects with observed spirometry data below the lower limit of normal (LLN) were also evaluated on each GLI-2012 equation of interest.

Results

This study included 567 subjects (250 men and 317 women) aged 6–79 years. Spirometry z-scores (z-FEV₁, z-FVC, and z-FEV₁/FVC) based on GLI-2012 Mixed equations had mean values close to zero (− 0.278 to − 0.057) and standard deviations close to one (1.001 to 1.128); additionally, 6.0% (95% confidence interval (CI) 3.1–8.9%) and 6.4% (95% CI 3.7–9.1%) of subjects were with observed data below LLN for FEV₁/FVC in men and women, respectively. In contrast, for NE Asian equations, all mean values of z-FEV₁ and z-FVC were smaller than − 0.5; for SE Asian equations, mean values of z-FEV₁/FVC were significantly smaller than zero in men (− 0.333) and women (− 0.440).

Conclusions

GLI-2012 equations for individuals of mixed ethnic origin adequately fitted spirometry data in this sample of Asian Americans. Future studies with larger sample sizes are needed to confirm these findings.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0658-9) contains supplementary material, which is available to authorized users.

Ethnic differences in spirometry measurements in China: Results from a large community-based epidemiological study

BACKGROUND AND OBJECTIVE

No previous studies have examined differences in spirometry measurements among ethnic populations in China, and factors which may influence ethnic differences are unclear. Our study aimed to investigate whether forced expiratory volume in 1 s (FEV₁ ) and forced vital capacity (FVC) differ among Han Chinese and other ethnic minorities in China.

METHODS

We recruited 7137 individuals aged 35-70 years from four areas of China inhabited by ethnic minority groups between 2007 and 2009. We conducted spirometry tests for all available participants, and compared FEV₁ and FVC among Uygur, Hui, Mongolian, Dai and Han Chinese ethnicities, using nonlinear multiplicative regression models.

RESULTS

A total of 2005 healthy never-smokers were enrolled in the analysis. For all ethnicities, spirometry values increased with height and decreased with age; FEV₁ and FVC were consistently higher in males than in females. Compared with Han Chinese, FEV₁ was 4.42% (95% CI: 2.11-6.78%) higher in Mongolians, 4.08% (95% CI: 1.33-6.76%) lower in Uygurs, 4.39% (95% CI: 1.33-7.35%) lower in Hui people and 4.72% (95% CI: 1.80-7.55%) lower in Dai people, after adjusted for potential confounders including height, age, sex and place of residence. We observed similar differences for FVC.

CONCLUSIONS

We detected significant differences in spirometry measurements among ethnic populations in China. Such differences cannot be fully explained by demographic, anthropometric or socioeconomic factors, but may also be attributed to genetic background as well as indoor and outdoor environmental exposures that need further investigation.

Spirometry Reference Equations from the HCHS/SOL (Hispanic Community Health Study/Study of Latinos)

RATIONALE

Accurate reference values for spirometry are important because the results are used for diagnosing common chronic lung diseases such as asthma and chronic obstructive pulmonary disease, estimating physiologic impairment, and predicting all-cause mortality. Reference equations have been established for Mexican Americans but not for others with Hispanic/Latino backgrounds.

OBJECTIVES

To develop spirometry reference equations for adult Hispanic/Latino background groups in the United States.

METHODS

The HCHS/SOL (Hispanic Community Health Study/Study of Latinos) recruited a population-based probability sample of 16,415 Hispanics/Latinos aged 18-74 years living in the Bronx, Chicago, Miami, and San Diego. Participants self-identified as being of Puerto Rican, Cuban, Dominican, Mexican, or Central or South American background. Spirometry was performed using standardized methods with central quality control monitoring. Spirometric measures from a subset of 6,425 never-smoking participants without respiratory symptoms or disease were modeled as a function of sex, age, height, and Hispanic/Latino background to produce background-specific reference equations for the predicted value and lower limit of normal.

MEASUREMENTS AND MAIN RESULTS

Dominican and Puerto Rican Americans had substantially lower predicted and lower limit of normal values for FVC and FEV₁ than those in other Hispanic/Latino background groups and also than Mexican American values from NHANES III (Third National Health and Nutrition Examination Survey).

CONCLUSIONS

For patients of Dominican and Puerto Rican background who present with pulmonary symptoms in clinical practice, use of background-specific spirometry reference equations may provide more appropriate predicted and lower limit of normal values, enabling more accurate diagnoses of abnormality and physiologic impairment.

Disparities in pulmonary function in healthy children across the Indian urban-rural continuum

RATIONALE

Marked socioeconomic health-care disparities are recognized in India, but lung health inequalities between urban and rural children have not been studied.

OBJECTIVES

We investigated whether differences exist in spirometric pulmonary function in healthy children across the Indian urban-rural continuum and compared results with those from Indian children living in the UK.

METHODS

Indian children aged 5 to 12 years were recruited from Indian urban, semiurban, and rural schools, and as part of the Size and Lung Function in Children study, London. Anthropometric and spirometric assessments were undertaken.

MEASUREMENTS AND MAIN RESULTS

Acceptable spirometric data were obtained from 728 (58% boys) children in India and 311 (50% boys) UK-Indian children. As an entire group, the India-resident children had significantly lower z FEV1 and z FVC than UK-Indian children (P < 0.0005), when expressed using Global Lung Function Initiative-2012 equations. However, when India-resident children were categorized according to residence, there were no differences in z FEV1 and z FVC between Indian-urban and UK-Indian children. There were, however, significant reductions of ∼ 0.5 z scores and 0.9 z scores in both FEV1 and FVC (with no difference in FEV1/FVC) in Indian-semiurban and Indian-rural children, respectively, when compared with Indian-urban children (P < 0.0005). z Body mass index, socioeconomic circumstances, tobacco, and biomass exposure were individually significantly associated with z FEV1 and z FVC (P < 0.0005).

CONCLUSIONS

The presence of an urban-rural continuum of lung function within a specific ethnic group emphasizes the impact of environmental factors on lung growth in emerging nations such as India, which must be taken into account when developing ethnic-specific reference values or designing studies to optimize lung health.

Lung function testing in children: importance of race and ethnic-specific reference equations

Marked differences in lung function occur between children of different racial and ethnic backgrounds even when all known confounders including socioeconomic circumstances have been taken into account. Use of ethnic-specific equations, such as those recently published by the Global Lung Function Initiative, help to minimize such differences, thereby improving the accuracy with which lung disease can be identified and treated during childhood, as well as enabling the true impact of adverse environmental or socioeconomic exposures to be assessed, irrespective of ethnic background. In future, incorporation of ancestry and, within emerging nations undergoing secular changes in anthropometry, sitting height, into normative equations may further improve the accuracy of predicting lung function and hence assessment of disease severity within any given individual.

Global differences in lung function by region (PURE): an international, community-based prospective study

BACKGROUND

Despite the rising burden of chronic respiratory diseases, global data for lung function are not available. We investigated global variation in lung function in healthy populations by region to establish whether regional factors contribute to lung function.

METHODS

In an international, community-based prospective study, we enrolled individuals from communities in 17 countries between Jan 1, 2005, and Dec 31, 2009 (except for in Karnataka, India, where enrolment began on Jan 1, 2003). Trained local staff obtained data from participants with interview-based questionnaires, measured weight and height, and recorded forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC). We analysed data from participants 130-190 cm tall and aged 34-80 years who had a 5 pack-year smoking history or less, who were not affected by specified disorders and were not pregnant, and for whom we had at least two FEV₁ and FVC measurements that did not vary by more than 200 mL. We divided the countries into seven socioeconomic and geographical regions: south Asia (India, Bangladesh, and Pakistan), east Asia (China), southeast Asia (Malaysia), sub-Saharan Africa (South Africa and Zimbabwe), South America (Argentina, Brazil, Colombia, and Chile), the Middle East (Iran, United Arab Emirates, and Turkey), and North America or Europe (Canada, Sweden, and Poland). Data were analysed with non-linear regression to model height, age, sex, and region.

FINDINGS

153,996 individuals were enrolled from 628 communities. Data from 38,517 asymptomatic, healthy non-smokers (25,614 women; 12,903 men) were analysed. For all regions, lung function increased with height non-linearly, decreased with age, and was proportionately higher in men than women. The quantitative effect of height, age, and sex on lung function differed by region. Compared with North America or Europe, FEV1 adjusted for height, age, and sex was 31·3% (95% CI 30·8-31·8%) lower in south Asia, 24·2% (23·5-24·9%) lower in southeast Asia, 12·8% (12·4-13·4%) lower in east Asia, 20·9% (19·9-22·0%) lower in sub-Saharan Africa, 5·7% (5·1-6·4%) lower in South America, and 11·2% (10·6-11·8%) lower in the Middle East. We recorded similar but larger differences in FVC. The differences were not accounted for by variation in weight, urban versus rural location, and education level between regions.

INTERPRETATION

Lung function differs substantially between regions of the world. These large differences are not explained by factors investigated in this study; the contribution of socioeconomic, genetic, and environmental factors and their interactions with lung function and lung health need further clarification.

FUNDING

Full funding sources listed at end of the paper (see Acknowledgments).

Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations

The aim of the Task Force was to derive continuous prediction equations and their lower limits of normal for spirometric indices, which are applicable globally. Over 160,000 data points from 72 centres in 33 countries were shared with the European Respiratory Society Global Lung Function Initiative. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5-95 yrs. Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family. After discarding 23,572 records, mostly because they could not be combined with other ethnic or geographic groups, reference equations were derived for healthy individuals aged 3-95 yrs for Caucasians (n=57,395), African-Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV(1)) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV(1)/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed. Spirometric prediction equations for the 3-95-age range are now available that include appropriate age-dependent lower limits of normal. They can be applied globally to different ethnic groups. Additional data from the Indian subcontinent and Arabic, Polynesian and Latin American countries, as well as Africa will further improve these equations in the future.

The use of ethnically specific norms for ventilatory function in African-American and white populations

BACKGROUND

In the USA, different standards are usually set for spirometric values in African-American and white populations. It is unclear to what extent the lower lung function found in African-Americans is 'normal' in the sense of having no adverse consequences.

METHODS

African-American and white participants in the Atherosclerosis Risk in Communities (ARIC) limited access data set, from four communities in the USA had spirometric testing at baseline beginning in 1986 and were followed up to assess survival to the end of 2002.

RESULTS

Forced Expiratory Volume in 1 s (FEV(1)) and Forced Vital Capacity (FVC) were lower in the African-American than the white sample both for men and women and adjustment for potential confounders had little effect on the estimated difference {difference in FVC after adjustment: men, -0.68 l [95% confidence interval (95% CI) -0.75 to -0.61]; women, -0.41 l (95%CI -0.45 to -0.36)}. The FEV(1)/FVC ratio was slightly greater among African-American than white participants [difference: men, 1.5% (95%CI 0.7-2.1); women, 1.7% (95%CI 1.1-2.2)]. After adjustment for age and height, survival was similar in each ethnic group for any given level of FVC before and after adjustment for potential confounders. The hazard ratio for African-American compared with white participants was 1.24 for men (95% CI 0.91-1.69) and 0.96 for women (95% CI 0.66-1.38).

CONCLUSIONS

A given FVC has the same prognostic significance for 'normal' African-American and white participants. It is inappropriate to use ethnic norms when assessing prognosis.

Lung function testing in health and disease: issues pertaining to Asia-Pacific populations

The Asia-Pacific region comprise of diverse ethnic populations and healthcare systems of highly variable developmental stages. We face challenges in lung function testing, many of which are different from the issues encountered in the west. In some places, access to proper lung function testing facilities is very limited due to resource constraints or geographic inconvenience. It is important to note the potential differences of normative values in Asia-Pacific populations, compared with established values derived from populations of Caucasian ethnicity, hence the need to choose from available prediction formulae the ones that most closely approximate the subjects being tested. The criteria for defining abnormality is a hot topic globally. In the Asia-Pacific region, the trade-off between simplicity and thus ease of application and the pitfall of under- or over-diagnosis based on fixed cut-off values has to be recognized. The promotion of wider availability and proper utilization of lung function testing will go a long way in the enhancement of respiratory health and disease management in the region.