Lung function measurements in children - copsac
Lung function measurements in children - copsac
Lung function measurements in children - copsac
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Normative data<br />
In the second part of the study a center effect could not be found, probably because<br />
center no. 1 was corrected and center no. 6 did not participate. Atopy and smok<strong>in</strong>g did<br />
not significantly differ between centers (Table 2).<br />
A British cohort study found that <strong>children</strong> of atopic parents and those with personal<br />
atopy had impaired lung <strong>function</strong> at the age of 3 years, even <strong>in</strong> the absence of<br />
respiratory symptoms (20). The high <strong>in</strong>cidence of parental atopy <strong>in</strong> our study could be a<br />
selection bias but we did not f<strong>in</strong>d a statically difference between atopic disposed and<br />
non-disposed <strong>children</strong>.<br />
Most papers have reported association between parental smok<strong>in</strong>g and impaired lung<br />
<strong>function</strong> <strong>in</strong> wheez<strong>in</strong>g or asthmatic young <strong>children</strong> (57-59); some have <strong>in</strong>vestigated the<br />
effect of parental smok<strong>in</strong>g <strong>in</strong> healthy <strong>children</strong> (60-62) and found reduced lung <strong>function</strong><br />
<strong>in</strong> healthy <strong>in</strong>fants. The ratio of smok<strong>in</strong>g parents <strong>in</strong> the normative data corresponds the<br />
smok<strong>in</strong>g habit <strong>in</strong> the Danish population (63). The complex <strong>in</strong>teraction of genetic and<br />
environmental factors <strong>in</strong>fluence the development of airway disease and dim<strong>in</strong>ished lung<br />
<strong>function</strong> (20, 64). We did not f<strong>in</strong>d an effect of the child’s history of atopy, parental<br />
atopy or smok<strong>in</strong>g on lung <strong>function</strong> <strong>in</strong> our study, this could be biased by either the<br />
relatively small population, or the <strong>children</strong> with atopy, parental atopy or smok<strong>in</strong>g could<br />
be a selected healthy population.<br />
We previously reported normative values from a population of 121 <strong>children</strong> 2-5 years of<br />
age (12); mean sRaw (SD) was 1.31 (0.20). Z-score was -0.5 between the two data sets.<br />
No other reference value for sRaw TOT has been reported, other studies have reported<br />
values of sRaw max (54, 65, 66).<br />
The variance was higher <strong>in</strong> the new collected data (SD 0.33) compared to previous<br />
reported (SD 0.2). This could be expla<strong>in</strong>ed by a small non-significant center variance.<br />
The previous population differs from the current <strong>in</strong> several follow<strong>in</strong>g aspects: 1)<br />
Measurements were done at one center; 2) exclusion of <strong>children</strong> exposed to tobacco<br />
smoke and anyone with a history of eczema or doctor-diagnosed atopy <strong>in</strong> first-degree<br />
relatives; 3) The study <strong>in</strong>cluded more 2- and 3-year-old <strong>children</strong>; many of these<br />
<strong>measurements</strong> had an accompany<strong>in</strong>g adult <strong>in</strong> the whole-body plethysmograph. The<br />
current data only <strong>in</strong>cluded <strong>children</strong> who performed a lung <strong>function</strong> measurement alone.<br />
The exact same equipment (unchanged hardware and software) at center no. 3 was used<br />
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