The objective of this study was to validate the established lung function norms that are commonly used in Asia, in particular in Hong Kong, for contemporary use. We compared the lung function indexes in a contemporary cohort of Hong Kong university students with established norms that were derived 20 years ago. These students were born at the time that the norms established by Lam et al were published. Discordance of our findings with those of Lam et al supports changes in the Hong Kong population over one generation. Any comparative interpretation must be guarded, however, given that several factors, including technological, environmental, and lifestyle factors, could explain the discrepancy in lung function.
Instrumentation and standardization of testing and measurement procedures are well known for influencing the reliability and validity of lung function measures. However, even though the spirometers used in the present study and in those of the study by Lam et al were produced by different manufacturers, both systems were calibrated prior to use. Further, the difference in time frame in measures between the two studies was one generation, roughly 20 years, during which time one might expect the effect of instrumentation differences in pulmonary function measurement to be minimal.