|dc.description.abstract||Since the late 1960s the safety of inhaled B2-agonists has been questioned and the longtenn
regular use of these drugs has been linked to increasing morbidity and mortality.
National and international guidelines recommend that short acting inhaled B2-agonists
should only be used on an "as needed" basis and yet the evidence for these
recommendations is still unclear, one reason being the lack of common definition for an
outcome. The Regular Use of Salbutamol Trial (TRUST) was designed to assess the
risks and benefits of regular versus as needed salbutamol in mild to moderate asthma.
In order to establish whether a common primary outcome measure could improve the
comparability and interpretation of different trials, a systematic rcyiew of randomised
controlled trials of long and short acting inhaled B2-agonists in asthmatic subjects was
undertaken to identify well designed trials in this field and primary outcome measures
used. The systematic review identified five different primary outcome measures from
26 trials of long and short acting inhaled B2-agonists. The TRUST definition of
exacerbation was compared with the five primary outcome measures identified using
the TRUST diary card data. In addition, the diary card variables (changes in PEF,
symptom scores and medication use) were examined to determine the extent to which
they predicted exacerbations according to the different definitions.
The use of additional corticosteroids and an increase in daytime symptoms of two or
more above baseline were the strongest predictors of all four definitions of
exacerbation. A fall in morning PEF of 100 lImin was strongly associated with all
definitions of exacerbation but was not a sensitive measure.
In conclusion, exacerbations of asthma could be identified by use of additional
corticosteroids and an increase in two or more of daytime symptoms. The specificity
could be improved by including morning PEF but this may reduce patient compliance
with study protocol in asthma trials.||en_US