PD50 - Impaired lung function in asthmatic schoolchildren – evaluation of risk factors

In this retrospective study we investigated risk factors for impaired lung function based on medical records of asthmatic children treated in a tertiary hospital between October 2004 and December 2008. Baseline characteristics, lung function measurements and current medication were charted. Those 430 children with data on ≥2 lung function measurements performed ≥5 years apart, were included in the analyses.

Altogether 91 (21%) children had abnormal findings in the first lung function measurement (n=38/265 in oscillometry performed at the median age of 4.2 years, and n=53/165 in spirometry performed at the median age of 7.6 years) and 183 (43%) in the last spirometry performed at the median age of 13.8 years. There were significant correlations between the oscillometry and last spirometry parameters: r=-0.243 between R5 z-score and FEV1 (p<0.001)(Fig.1), and r=-0.197 between R5 z-score and FEV1/FVC (p=0.001). Correlations between the first and last spirometry parameters were also significant: r=0.547 for FVCs, r=0.486 and for FEV1s, r=0.450 for FEV1/FVCs, and r=0.496 for ln(MEF50%)s (p<0.001 in every comparison). There was a significant, albeit mild, correlation between the need of medication and decrease in FEV1/FVC and MEF50% (rs=-0.098; p=0.043, and rs=-0.097; p=0.045). In multivariate analyses, male gender, a birth weight of <1500 g, duration of asthma, and abnormal oscillometry or spirometry parameters in the first lung function measurement were significant risk factors for impaired lung function in adolescence.

Figure 1

In conclusion, male gender, a very low birth weight, and the duration of asthma interfere with the lung function development. In addition, impaired lung function appears to persist despite regular asthma control medication.