View - ResearchSpace@Auckland - The University of Auckland

the Paediatric Society of New 7*aland which I co-chaired (Byrnes, Vogel et al. 2005) and a
report from the Agency for Healthcare Research and Quality, from the United States
Department of Health and Human Services (Viswanathan, King et al. 2003).
1.4.3 Where does coughfit in?
The use of cough as a diagnostic symptom is another area that is not straightforward. When
asked what clinical factors were associated with establishing an initial diagnosis of asthma,
96Vo of the responding clinicians thought the requirement was recurrent wheeze, 90Vo
symptomatic improvement with a bronchodilator, and 89Vo recunent cough, but there was
disagreement over what combinations of these factors were important (Werk, Steinbach et al.
2000). "Troublesome cough is a characteristic of asthma" (Li, I-ex et al. 2003) and "cough is
as frequent a symptom as is wheezing" (Weinberger and Abu-Hasan 2006) has been reported.
Controversy has focused on whether 'cough variant asthma' (sometimes called 'cough
equivalent asthma') truly exists, with researchers both for and against.
It is thought that asthma could occur without wheezing if the obstruction involves the small
airways predominantly, and then coughing or shortness of breath may be the only complaint
(Kercsmar 2006).In a follow-up study of I25 preschool children with recurrent cough but no
other symptoms at the time of enrolment, 56Vo of them were symptom free at follow-up while
36.8Vo continued to have recurrent cough in the absence of a 'cold', and7 .2Vo had developed
recurrent episodes of wheeze @rooke, Lambert et al. 1998). One hundred children with a
mean age of 5.7 years with chronic cough were followed for three years. Of the 75 deemed as
having 'cough variant asthma', 28 (377o) went on to develop more 'classical' asthma
symptoms (Todokoro, Mochizuki et al.2N3). Bronchial hyper-reactivity, nocturnal cough
and developing cough at an earlier age may each be predictors of those who go on to get more
typical asthmatic symptoms (Brooke, Lambert et al. 1998), (Todokoro, Mochizuki et al.
2003).It has been suggested in adults that those with cough who go on to develop classical
asthma have a threshold for airway hyper-responsiveness somewhere between asthmatic and
normal subjects (Koh, Jeong et al. 1999; Mochizuki, Arakawa et al. 2005) and 30Vo of those
with cough and bronchial hyper-responsiveness will go on to develop asthmatic symptoms
(Fujimura, Nishizawa et al. 2005). Eosinophilic inflammation (eosinophils, eosinophil
cationic protein (ECP), interleukin 5 (IL5)) has been demonstrated in some patients with
persistent cough; a pattern of inflammation similar to asthmatics seen in adults (Lee, Cho et
al. 200| De Diego, Martinez et al. 2005) and in children (Yoo, Koh et al.2004). Basement
membrane thickening, a pathological feature of asthma, was demonstrated in 'classical'
l0