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asthmatics at 8.6 microns, in 'cough variant asthmatic' subjects at7.l microns and both were
significantly different than healthy controls at 5.0 microns (Niimi, Matsumoto et al. 2000).
Others are less enthusiastic for this diagnostic category -
given that cough is a very corlmon
symptom. A diagnosis of cough variant asthma could result in a significant increased number
of children being treated' "Isolated chronic cough in children is rarely asthma, and the term
'cough-variant-asthma' should not be used" (Chang, Landau et al. 2006). Wheezing reported
by children had a very good discriminating ability for asthma whereas cough less so in over
1600 school children aged 8-12 years (Yu, Wong et aI.2004). In asthmatic children who had
cough as a predominant symptom, the cough occurred early and heralded the onset of an
exacerbation. Asthma scores did relate to cough scores, although neither cough receptor
sensitivity nor cough scores related to any specific inflammatory marker (Chang, Harrhy et al.
2002). In 1245 children 6-12 years of age comparing symptoms of persistent cough with
symptoms of wheeze, the former had less demonstrable atopy and less morbidity. The authors
concluded that while 'cough variant asthma' was not shown, there remained a significant
number of children with persistent cough diagnosed and treated as having asthma @aniran,
Peat et al. 1999). So in the presence of persistent cough, if history, examination, chest x-ray
and spirometry are normal, the cough could be regarded as non-specific and the child
regarded as in the category of 'normal', as opposed to heralding a morbid or pre-morbid
condition (Chang and Powell 1998; Bush 2002).
Finally, treatment trials for cough using inhaled corticosteroids (IHCS) (Dicpinigaitis 2006;
Matsumoto, Niimi et aL.2006) and a leukotriene receptor antagonist (Spector and Tan 2004)
showed an improvement in symptoms. However the natural history of post-viral cough is that
most will have resolved in 3-4 weeks and only l\Vo will continue for more than 25 days, with
gradual resolution. Improvement could therefore have erroneously been attributed to
treatment. The Cochrane Systematic Review of the efficacy of IHCS for non-specific cough
in children > two years of age evaluated two trials enrolling a total of 123 children. The first
trial using beclomethasone dipropionate 4o0ltglday (metered dose inhaler via a spacer) found
no difference from placebo in reducing cough frequency measured objectively or scored
subjectively. The second trial using fluticasone propionate 2mglday for three days followed
by I mg/day for 1l days (metered dose inhaler via a spacer) showed a significant
improvement in nocturnal cough frequency after two weeks, but also with a significant
(though smaller) improvement with placebo (Tomerak, McGlashan et al. 2005). There was no
difference between the use of inhaled salbutamol and placebo (Tomerak, Vyas et al. 2005) or
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