Disparities in Pulmonary Function in Healthy Children across the Indian Urban–Rural Continuum

Abstract

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 FEV 1 and z FVC than UK-Indian children (P , 0.0005), when expressed using Global Lung FunctionInitiative-2012 equations. However, when India-resident children were categorized according to residence, there were no differences in z FEV 1 and z FVC between Indian-urban and UK-Indian children. There were, however, significant reductions of z0.5 z scores and 0.9 z scores in both FEV 1 and FVC (with no difference in FEV 1 /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 FEV 1 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

“…Thus while there was approximately 11% reduction in FEV 1 and FVC among Indian children attending school in either London or Bangalore city, this difference increased to approximately 21% in children exposed to severe poverty within the rural and semiurban areas when compared with White children of similar age, height and sex [20]. These observations highlight how essential it is, when attempting to establish reference ranges within any given ethnic group, to limit recruitment of 'healthy' subjects to well-nourished individuals who have not been exposed to extreme degrees of either social deprivation or environmental pollution.…”

“…By contrast, the impact of severely adverse socioeconomic circumstances within any specific ethnic group is apparent from the significantly lower lung function observed in Indian children living in semiurban and rural areas when compared with their better-nourished peers attending school in Bangalore city, who were assessed using identical equipment and protocols [20]. Thus while there was approximately 11% reduction in FEV 1 and FVC among Indian children attending school in either London or Bangalore city, this difference increased to approximately 21% in children exposed to severe poverty within the rural and semiurban areas when compared with White children of similar age, height and sex [20].…”

“…In the past, attempts to interpret observed ethnic differences in lung function were often confounded by selection bias related to use of small population samples that were not necessarily representative or generalizable, use of different equipment, methods and quality control criteria, failure to adjust for other important determinants of lung function, including socioeconomic circumstances and/or inappropriate statistical analyses. In recent years, many of these problems have been addressed by applying standardized methodology, inclusion criteria and quality control to large, ethnically homogenous groups studied within the context of multiethnic populations [2,5,6,8,17] [5,17,20] and Southeast Asian (e.g., China, Thailand, Malaysia) subjects [2]. Since these 'ethnic' reductions in FEV 1 and FVC are proportional, the FEV 1 /FVC ratio, which is the most commonly used outcome to assess airways obstruction, is independent of ethnic background [2,17,18,21].…”

The Tools of the Trade – Physiological Measurements of the Lungs

“…There are well established guidelines for children [4], however, since ethnic differences in lung function are known to exist [5], accurate interpretation of spirometry in children from different ethnic backgrounds is not feasible without using appropriate reference data [6]. The most comprehensive spirometric reference data to date are the BAll-Age^equations by Stanojevic et al [7], which are available for White subjects aged 3 to 80 y of age and several normative values are available for Indian children [5,[8][9][10].…”

Lung function, genetics and socioeconomic conditions

“…Similarly, the transfer factor of the lung for carbon monoxide (TLCO)/alveolar volume (VA) ratio does not differ between Europeans and East-Asians [28], nor are lung elastic properties different [29]. Although there are clear differences in FEV1 and FVC related to SEC, and between urban and rural populations, there is no such pattern for the FEV1/FVC ratio [30,31]. Reports on differences in chest circumference are inconclusive, possibly because this index is highly associated with body mass and also, possibly, because of heterogeneity in measurement protocols.…”