Lung function reference values in Chinese children and adolescents in HongKong - I. Spirometric values and comparison with other populations

As part of a comprehensive evaluation of lung function in Hong Kong-born Ch inese children and adolescents, this study was conducted to determine updat ed prediction equations for spirometry, to evaluate the secular changes of lung function during the past decade, and to compare these results with oth er data sets. The results are based on 852 (392 male, 460 female) healthy s tudents, age 7 to 19 yr, recruited from seven schools in Hong Kong. Ail wer e born and lived in Hong Kong, nonsmokers, free from past or present sympto ms or diseases affecting the respiratory tract. A body plethysmograph was u sed to record lung function measurements. Natural logarithmic values of lun g volumes and body height were used in the final regression model. Predicti on equations for FVC, FEV1, and maximal expiratory flow at 50% of the FVC ( MEF50) for both sexes are presented, with standing height as the dependent variable. Compared with Hong Kong data from 1985, the results show a signif icant increase in height-corrected NC and FEV, in both boys and girls, over the whole height range. Compared with recent data of whites, FVC in boys w ere 8 to 10% lower in the study population, and the difference increased to 12% above the 165 cm height ranges, while FVC in Chinese girls had similar or only slightly lower predicted values. FEV, values showed a similar patt ern with lesser difference between the two ethnic groups. Compared with rec ent data from Chinese children in Singapore, a similar pattern with overall lesser difference of the two populations was present in boys, whereas ther e was no significant difference between girls in the two places. Our findin gs support the conclusion that exogenous factors may contribute significant ly to the differences in lung function values among ethnic groups and that it is important to examine normative values of various populations for secu lar trends.