Lum, S

Stocks, J

PubMed

UCL Discovery

Reply to letter by Huls et al. (ERJ-01465-2015.R2)“Inclusion of children with airway disease for the development of spirometry referencedata”Sooky Lum1 and Janet Stocks11Respiratory, Critical Care & Anaesthesia section (Portex Unit), UCL, Institute of Child Health,London, UKCorresponding authorSooky Lum (s.lum@ucl.ac.uk)Respiratory, Critical Care & Anaesthesia section (Portex Unit), UCL, Institute of Child Health,London, UKLink to ERJ: DOI: 10.1183/13993003.02028-2015“This is an author-submitted, peer-reviewed version of a manuscript that has been accepted forpublication in the European Respiratory Journal, prior to copy-editing, formatting and typesetting.This version of the manuscript may not be duplicated or reproduced without prior permission fromthe copyright owner, the European Respiratory Society. The publisher is not responsible or liablefor any errors or omissions in this version of the manuscript or in any version derived from it byany other parties. The final, copy-edited, published article, which is the version of record, isavailable without a subscription 6 months after the date of issue publication.”Inclusion of children with airway disease for the development of spirometry reference dataReply to letter by Huls et al.Dear SirWe wish to thank Dr Hüls and colleagues for their interest in our recent paper[1], and the opportunity toclarify the rationale behind the conclusions we reached, which differ from their own. Despite the title of theirletter, it is important to emphasise that we did not recommend inclusion of symptomatic children, those witha prior history of adverse exposures, or those with current respiratory illness such as asthma, whenestablishing spirometric reference equations, where international standards regarding definition of healthmay need to be adhered to. Indeed we state clearly in the discussion that under such circumstances, thetarget sample size may have to be increased by at least 30% to account for such exclusions, a proportionnot dissimilar to that reported by Hüls et al. What was demonstrated by our results is that when carryingout epidemiological studies such as the Size and Lung function In Children (SLIC) study[2], the primary aimof which was to ascertain the extent to which ethnic differences in lung function can be attributed todifferences in physique and socioeconomic factors, inclusion criteria can be broader without biasing results.This not only renders the results more generalisable but has considerable practical and economic benefits.Although the authors compared their data from the LUNOKID study with our results, there are differencesregarding the definition of ‘current asthma’ between the two studies. Thus, whereas ‘current asthma’ wasapparently categorised according to current medication in the LUNOKID study, within the SLIC study‘current asthma’ was defined as those with ‘either doctor-diagnosis or asthma medication in the past 12months, with or without current symptoms/wheeze’, ensuring that any child with a prior history of asthmawas only included if asymptomatic and without treatment for at least 12 months. Despite these differencesin asthma classification, it is reassuring to know that “no relevant mean differences were found for the othersubgroups or for the total study population when all subgroups were included” within the LUNOKID study,thereby confirming our findings from the SLIC study. Both studies also agree on the higher failure rate dueto technically unsatisfactory data when including children with respiratory symptoms. However, while theLUNOKID authors argue that due to potential difficulties in separating upper and lower respiratory tractinfections, ‘strict criteria to define a healthy population should be adhered to’, our experience suggests thatany naïve child (i.e. one unfamiliar with spirometric assessments) with significant respiratory symptoms islikely to be self-excluded provided strict quality control is applied, and that exclusion of a high proportion ofthe population on ‘health grounds’ could result in over-estimation of abnormalities and potential mis-management of lung disease.In conclusion, while we completely agree that inclusion and exclusion criteria applied to subjects must varyaccording to the underlying question and study design, we would like to confirm that we excluded resultsfrom any children with current asthma or who were on asthma medication. For the purposes of datacollection in population-based studies of lung function such as the SLIC study, we stand by our conclusionthat with exception of clear-cut factors such as current and chronic respiratory disease, paediatric referencesamples for spirometry can be relatively inclusive and hence more generalisable to the general population.References1. Lum S, Bountziouka V, Sonnappa S, Cole TJ, Bonner R, et al. (2015) How "healthy" should children bewhen selecting reference samples for spirometry? Eur Respir J 45: 1576-1581.2. Lum S, Bountziouka V, Sonnappa S, Wade A, Cole TJ, et al. (2015) Lung function in children in relationto ethnicity, physique and socioeconomic factors. Eur Respir J 46: 1662-1671.

Inclusion of children with airway disease for the development of spirometry reference data

http://discovery.ucl.ac.uk/1477376/1/SLIC_ReferencePopulation_Reply_to_HulsLetter_ERJ_April2016.pdf

Inclusion of children with airway disease for the development of spirometry reference data

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