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Re: Lum S, Hoo AF, Hulskamp G, Wade A, Stocks J. potential misinterpretation of infant lung function unless prospective healthy controls are studied. Pediatr pulmonol 2010;45:906–913

To the Editor: We congratulate Lum et al. for their careful analysis of infant lung function measurements in a cohort of healthy British infants. They demonstrated that forced expiratory flow measurements obtained with the Jaeger MasterScreen BabyBody system differed significantly and systematically from those published by Jones et al., and were able to mathematically adjust for these differences. These authors conclude that ‘‘if infant lung function tests are to have any significant future role, a concerted effort from members of the ATS/ERS working group on infant and lung function tests to present the rationale and safety data to support recruitment of healthy infants for lung function tests, and discourage usage of such tests in the absence of adequate controls. . .’’. We respectfully suggest that this conclusion may not be supported by their study. Lum et al. demonstrated that data from healthy infants published by Jones et al. does not provide a similar normative range as those in their study using a different piece of equipment and different software. Although Lum et al. sought technical reasons for these differences, they were not able to be clearly elucidated. Jones et al. provided a careful study of 155 infants (mean age 48 weeks, 43% female, 69% Caucasian), from two tertiary US children’s hospitals. The mean length of their subjects was 71.8 cm, and 49% had post-natal tobacco smoke exposure. These authors used equipments that were eventually commercialized (Infant Pulmonary Lab) with the support of the US Cystic Fibrosis Foundation by Ferraris-Collins and presently distributed by nSpire Health (Longmont, Colorado). In contrast, Lum et al. studied 66 infants (mean age 51.2 weeks, 60% female, 100% Caucasian) on 89 occasions, with a mean length of 75.4 cm. It is unclear whether the differences in these two populationsmight be enough to result in some of the differences in measured flows and volume. Lum et al. are correct to assert that data obtained from infants studied with one system should only cautiously be compared to normative data obtained from a different system. It should be noted that lung function testing may serve other purposes beyond determination of whether measurements are in the normal range or not (e.g., assessing for longitudinal changes due to disease or treatments within patients). These roles for lung function testing are less dependent on the normative data utilized for a study. They also note that ‘‘during recent years there has been ongoing debate as towhether it is ethical to undertake lung function tests under sedation in healthy infants.’’ This does not fully acknowledge the issue as seen by most US Institutional ReviewBoards. According to the USCode of Federal Regulations, research involving children can be conducted if: