Smokers with newly diagnosed asthma are likely to derive a similar benefit from inhaled budesonide, in terms of lung function, as their nonsmoking counterparts, a recent study indicates.

"Previous studies have suggested a reduced benefit from inhaled corticosteroid (ICS) therapy in asthmatic smokers," Dr. Paul. M. O’Byrne of McMaster University Medical Center in Hamilton, Ontario, Canada and colleagues point out in the December issue of the journal Chest.

Because forced expiratory volume in 1 second (FEV1) is known to drop over time in patients with asthma, the researchers compared this outcome in a subset of smokers and nonsmokers in the 3-year START trial. That study randomized patients with mild, newly diagnosed asthma to treatment with either budesonide (400 mcg daily) or placebo.

Changes in concurrent asthma medication were allowed during the study, at the investigator’s discretion, to achieve asthma control.

The present analysis focused on 492 smokers and 2432 nonsmokers.

In agreement with other studies, Dr. O’Byrne and colleagues note, asthmatic smokers who received placebo had a greater decline in lung function than asthmatic nonsmokers.

Specifically, in the placebo group at 3 years, post-bronchodilator therapy FEV1 declined by 263.9 mL in smokers (-7.7% predicted normal) and by 180.8 mL in nonsmokers (-5.8% predicted normal). The mean difference was -83.1 mL (p < 0.001).

Of note, inhaled budesonide was "equally effective in attenuating this decline in post-bronchodilator therapy FEV1 in smokers and in nonsmokers," the investigators report.

In budesonide-treated patients, they add, FEV1 had declined at 3 years by 192.4 mL in smokers (-5.7% predicted normal) and 134.3 mL in nonsmokers (-4.8% predicted normal).

The overall mean treatment effect of budesonide was 59.0 mL. The benefit of budesonide over 3 years was 71.5 mL (p = 0.011) in smokers and 46.5 mL (p = 0.001) in nonsmokers. The corresponding effect in pre-bronchodilator therapy FEV1 was 118.1 mL (p = 0.002) in smokers and 72.9 mL (p < 0.001) in nonsmokers.

The risk of having a first severe asthma-related event was significantly reduced by budesonide therapy (hazard ratio, 0.50; p < 0.001) and no significant difference was seen between smokers and nonsmokers.

These findings, the investigators conclude, suggest that, at least for changes in FEV1 over time, ICS therapy provides a benefit in both smokers and nonsmokers with mild, persistent asthma.

"Indeed, the magnitude of the benefit was numerically (although not significantly) larger in asthmatic patients who smoke," they point out.

The START study was funded by AstraZeneca, which markets inhaled budesonide as Pulmicort.

Chest 2009;136:1514-1520.

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