Ethnic differences in lung functions of children in the Colombo District, Sri Lanka.

Background: Reference values of lung functions vary with age, height, ethnicity and sex of the reference population. Global Function Initiative 2012 compared reference equations for Sri Lankan children with those of South Indian and South East Asian equations. Sri Lanka has a multi-ethnic society comprising of Sinhalese, Tamils, Moors and other ethnic minorities. Applicability of existing Sri Lankan equations to children from different ethnic groups in the country has not been adequately verified. Our aim was to investigate the effect of ethnicity on spirometry parameters in school aged children.

Methods: We enrolled healthy boys and girls between 9-15 years of age from 6 schools in Colombo District using stratified cluster sampling. A pretested self-administered questionnaire collected details on demography, respiratory health and other chronic illnesses. Anthropometric measurements (standing height and weight) were collected. Spirometry was performed with a flow sensing spirometer that complies with American Thoracic Society/European Respiratory Society (ATS/ERS) standards adopted for children. Highest FVC and FEV1 values were obtained from 2 repeatable tests.

Results: Spirograms of 849 students were analysed. Majority (n=496) were Sinhalese. There were 240 Tamils and 113 Moors. Multiple regression found that height, age and sex were significantly associated with lung functions (p<0.05). Ethnicity was not significantly associated with parameters measured in spirometry when the regression was performed controlling for height and age.

Conclusions: The same spirometry reference equations could could be used for children of all ethnic groups in Sri Lanka aged 9-15 years.