Treatment for mild asthma improves lung function

A study by the Woolcock Institute of Medical Research in Sydney is the first to demonstrate that in patients with very mild or well-controlled asthma, regular treatment with low dose ICS leads to significantly better day–to-day lung function.

The study published in this month’s edition of Primary Care Respiratory Journal was conducted over an 11 month period, and compared the effects of inhaled corticosteroids (ICS) and placebo on asthma control in mild asthmatics.

The results of the study raise questions about the current emphasis in asthma treatment which is based largely on controlling symptoms, and which does not advocate ICS treatment for patients with symptoms two days a week or less.

Results showed significant and clinically important treatment benefits on markers such as lung function, airway hyperresponsiveness and exhaled nitric oxide, which are all predictors of the risk of future adverse outcomes such as exacerbations.

Results indicated that a “ceiling” effect for lung function, often assumed to prevail in mild asthma, does not exist. Even patients whose lung function is over 90% of predicted normal value may have room to further improve their personal best with treatment.

The study also demonstrated subjects receiving placebo were nearly three times more likely to experience a mild exacerbation. “In recent years the emphasis in asthma treatment has been on how well a patient’s symptoms are is controlled,” says Woolcock research leader Assoc. Prof. Helen Reddel.

“The patients in this study had asthma that was so mild, with symptoms once a week or less, that they themselves didn’t see any benefit in regular preventer treatment,” she said.

“However for those participants receiving ICS during the study, their lung function was better, they had less airway inflammation and less airway twitchiness. All of these things are predictors of reduction in risk of future adverse outcomes “While we’re not advocating that every patient with mild asthma should be on preventer medication, the
study shows that when we are discussing the risks and benefits of treatment with these patients, we should talk about their risk of future exacerbations as well as whether they will notice any difference in their current symptoms”.

“In the same way, for patients with high blood pressure, we talk about giving treatment to reduce their risk of stroke in the future rather than whether they will feel any different here and now.” Dr Reddel explains that while the study sample size was small, the measurement of airway twitchiness, airway inflammation and daily spirometry provided information about future risk that is often not possible in larger groups.

(Source: Primary Care Respiratory Journal: Lucy Williams: Woolcock Institute of Medical Research: March 2008)