DiscussionAlthough there is a pleth

Discussion
Although there is a plethora of asthma symptom questionnaires,
this is the first to be specifically developed and
validated to measure asthma control. The authors first
examined the goals of asthma treatment [1±3, 10] and then
sought consensus from international opinion leaders concerning
the symptoms and measures of airway calibre that
are most important for assessing asthma control. Agreement
was sufficiently high for the authors to have confidence
in selecting the top scoring items for the ACQ.
The technique used to develop the ACQ is unique in that
a large number of leading asthma clinicians from around
the world participated in identifying the questions that
should be included. The authors interpret the high response
rate as an indication of the importance they place upon this
instrument to help disseminate the concept and goals of
optimum asthma management. The high level of consensus
among clinicians removes any ambiguities that may
have existed concerning the meaning of optimum asthma
control.
This study has shown that the ACQ has strong measurement
properties both as an evaluative and as a discriminative
instrument and can be used with confidence in
both clinical trials and cross-sectional surveys. The ACQ is
needed for research studies to measure the primary goal of
asthma treatment, to identify populations at risk and to
facilitate comparison of results across studies.
To meet the authors' specifications of brevity and completion
in the clinic, the ACQ includes only those symptoms
that most commonly reveal lack of control in the
majority of patients and does not include daily PEF
measurement. Nevertheless, it is believed that there is an
important role for the ACQ in the management of individual
patients in both general practice and tertiary care.
Not only does the ACQ allow clinicians to become familiar
with the goals of asthma management, but it can also
identify patients with poor control and, more accurately
than recall, evaluate the effects of interventions. In addition,
completion of the ACQ in the waiting room may save
consultation time and group monitoring may be used to
enhance disease management and thus reduce resource
utilization.
For categorizing patients into the stable and unstable
groups, it would have been ideal for several clinicians,
blinded to the ACQ data, to have independently assessed
each patient at each clinic visit and a consensus taken as to
whether each patient had changed. This was not feasible
and left the choice of reviewing recorded data at a later date
for a group decision or having one clinician make the decision
at the time of the clinic visit. The latter was selected
because a group decision would have had to rely heavily
on recorded symptoms, b2-agonist use and airway calibre,
i.e. all the data recorded in the ACQ. The approach taken
makes it less likely that spuriously high correlations resulted
from ACQ data exercising undue influence on the
global rating.
A limitation of this study is the relatively small and possibly
homogeneous sample. Although the authors endeavoured
to enrol patients with a wide range of asthma
severity and socioeconomic background, most were Caucasian.
Testing of the Asthma Control Questionnaire in
other settings will increase confidence in the general applicability
of the results.