Lung Function in Children of Different Origins

Background:

Differences in lung function between people of varying ethnic origins are recognised, but the underlying physiological reasons have not been widely explored.

Aims:

The overall aim was to explore the physiological basis of differences in spirometry between white and South Asian children.

Methods:

We measured spirometry and maximum inspiratory pressures (MIP and MEP) in 307 children aged five to eleven years in primary schools. Spirometry included FEV1 and FVC. A subgroup of 37 children attended the laboratory for plethysmography and attempted measurements of distensibility of the respiratory system, made by measuring pressure and volume after brief interruptions of tidal breathing. Lung volumes were available from an additional 122 healthy children aged 7 to 16 years. Lung volume measurements were expressed as Z-scores based on predicted values for white children.

Results:

The mean(SD) FEV1 Z-scores for white and South Asian children were 0.17(1.01)and-0.55(0.97) respectively(p<0.001). Corresponding FVC Z-scores were 0.36(1.02) and-0.67(0.94), (p<0.001). We did not find significant ethnic differences in MIP or MEP. Adjusted mean(SD) MIP(kPa) was 7.51(1.99) for white and 7.02(1.91) for South Asians (p=0.14). Equivalent values for MEP(kPa) were 6.29(1.58) and 6.46(1.53), (p=0.48). Mean(SD) Z-scores for Total Lung Capacity were larger in white than south Asian children:(0.29(0.09) and -0.59(0.82) respectively, p<0.001). Mean(SD) Z-scores for Residual Volume were also larger in white children: (0.04(0.76) and -0.28(0.89) respectively, p=0.039). The measurements of distensibility yielded potentially useful data in 16/37 (43%) of children.