title: How "healthy" should children be when selecting reference samples for spirometry?
abstract: How "healthy" do children need to be when selecting reference samples for spirometry? Anthropometry and spirometry were measured in an unselected, multi-ethnic population of school children aged 5-11 years in London, UK, with follow-up assessments 12 months later. Parents provided information on children's birth data and health status. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were adjusted for sex, age, height and ethnicity using the 2012 Global Lungs Initiative equations, and the effects of potential exclusion criteria on the z-score distributions were examined. After exclusions for current and chronic lung disease, acceptable data were available for 1901 children on 2767 occasions. Healthy children were defined as those without prior asthma or hospitalisation for respiratory problems, who were born at full-term with a birthweight ≥2.5 kg and who were asymptomatic at testing. Mean±sd z-scores for FEV1 and FVC approximated 0±1, indicating the 2012 Global Lungs Initiative equations were appropriate for this healthy population. However, if children born preterm or with low birthweight, children with prior asthma or children mildly symptomatic at testing were included in the reference, overall results were similar to those for healthy children, while increasing the sample size by 25%. With the exception of clear-cut factors, such as current and chronic respiratory disease, paediatric reference samples for spirometry can be relatively inclusive and hence more generalisable to the target population.
authors.affiliation: Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK. s.lum@ucl.ac.uk.
authors.forename: Sooky
authors.initials: S
authors.lastname: Lum
authors.affiliation: Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Bountziouka
authors.affiliation: Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK. Institute of Global Health, University College London, Institute of Child Health, London, UK.
authors.forename: Samatha
authors.initials: S
authors.lastname: Sonnappa
authors.affiliation: Population, Policy and Practice Programme, University College London, Institute of Child Health, London, UK.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Cole
authors.affiliation: Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Bonner
authors.affiliation: Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK.
authors.forename: Janet
authors.initials: J
authors.lastname: Stocks
mesh_terms: D000886:Anthropometry; D001249:Asthma / Q000503:physiopathology*; D001724:Birth Weight; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume; D006304:Health Status; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D008137:Longitudinal Studies; D008168:Lung / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D018579:Patient Selection; D011446:Prospective Studies; D012016:Reference Values; D013147:Spirometry / Q000592:standards*; D014797:Vital Capacity