A new review appearing in issue 2 of Cochrane Library suggests that asthma treatment based on tests of fluid coughed up from the lungs could reduce the frequency and severity of flare-ups in adult asthma patients.

Asthma patients and their physicians typically head off asthma attacks by tracking the frequency of symptoms, such as wheezing and coughing, and use lung function tests to identify when airways become narrowed or inflamed.

Testing lung secretions offers another way to measure airway inflammation objectively and can help patients and doctors manage asthma, said, lead review author Helen Petsky, a respiratory nurse and project coordinator at the Royal Children’s Hospital in Queensland, Australia.

Petsky and co-authors evaluated research on the use of sputum analysis. When asthma patients experience the airway narrowing that precedes an asthma flare, they produce two kinds of white blood cells that are signs of inflammation. These cells—called eosinophils and neutrophils—show up in phlegm. Higher numbers of eosinophils indicate more severe airway inflammation.

This review looked at studies that compared sputum analysis monitoring to traditional symptom and lung-function monitoring. Data came from 221 adult patients in three studies conducted between 2002 and 2006.
Patients monitored with sputum analysis were significantly less likely to experience asthma flares, had a reduced frequency of flares and went longer without experiencing flares when compared to patients who only monitored asthma symptoms and lung function, the analysis showed.

Sputum monitoring might reduce the need for steroid medications prescribed to treat airway inflammation, the researchers wrote. However, the findings did not show significant differences in corticosteroid use between the treatment and control groups. Likewise, there was no difference in asthma symptoms or in quality-of-life scores between the control and treatment groups, the review authors reported.

The authors concluded that while sputum analysis could prove beneficial for adults with severe asthma, current research does not justify routine sputum analysis, since there have been few trials, variable definitions of asthma exacerbations, and uneven cut-off points for sputum eosinophils.