Regular salbutamol may increase risk of airflow obstruction
Regular inhaled short-acting beta agonists may increase the risk of future moderate or severe asthma attacks, authors of a letter published in Nature predict (2005;438:667).
Urs Frey, University Hospital of Berne, Switzerland, and colleagues analysed
data from a published double-blind crossover trial that compared the
effects of regular inhaled salbutamol (400µg four times daily)
with those of a regular long-acting beta agonist, salmeterol (50µg
twice daily), and placebo. All trial participants were taking similar
doses of inhaled corticosteroids throughout.
By looking at a series of 300 consecutive, twice daily peak expiratory
flow (PEF) measurements, the researchers predicted the risk of worsening
airflow obstruction.
This was done by calculating the conditional probability that, given
the current airway condition, a severe obstruction will occur within
30 days.
The researchers found that, for any value of PEF, regular salmeterol
decreased the probability that moderate or severe airflow obstruction
would occur within one month compared with placebo (P<0.004) and salbutamol
(P<0.02). However, salbutamol increased the risk of future moderate
or severe airflow obstruction beyond that seen with placebo, especially
for near normal values of PEF, they say. “Our results suggest that
the short-acting agonist treatment leads to significantly increased variability
and loss of predictability of airway function,” they conclude.
British Thoracic Society/Scottish Intercollegiate Guidelines Network
asthma treatment guidelines only recommend the use of short-acting beta-agonists
as required. |
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