Am. J. Respir. Crit. Care Med., Vol 154, No. 4, Oct 1996, 881-884.
Seasonal variations in house dust mite influence the circadian peak expiratory flow amplitude
GG Meijer, DS Postma, S van der Heide, DM de Reus, GH Koeter, RJ Roorda and WM van Aalderen
Department of Pediatric Pulmonology, Beatrix Children's Hospital, Groningen, the Netherlands.
The aim of the study was to investigate whether seasonal differences in
house dust mite (HDM) allergen exposure influence the circadian peak
expiratory flow (PEF) amplitude in asthmatic children. Asthmatic children
(n = 25) with a solitary allergy to HDM were studied in spring and in
autumn. All used inhaled corticosteroids (ICS) regularly. Six days after
withdrawal of ICS, PEF amplitude (every 4 h during 24 h,
highest-lowest/percentage of mean value) was assessed. HDM allergen (HDMA)
in living rooms, bedrooms, and mattresses was collected. HDMA levels were
not always highest in autumn. PEF amplitudes in spring and autumn did not
correlate with HDMA levels in the same season. However, the seasonal
difference in PEF amplitude (autumn value - spring value) correlated
positively and significantly with the seasonal difference in HDMA exposure
levels from the mattresses (rho = 0.34, p < 0.05). Multivariate analysis
showed that the seasonal difference in HDMA exposure in the mattress was
the single parameter explaining seasonal difference in PEF amplitudes by
21.0% (p = 0.02). Our cross-sectional study showed a higher PEF amplitude
not to be significantly associated with higher HDMA exposure in mattresses
in a group of HDM-allergic asthmatic children. However, the change in HDMA
exposure over seasons contributed significantly to the change in PEF
amplitude after withdrawal of ICS in HDM-allergic asthmatic children.