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Managing Asthma by Eosinophil Count
Am Fam Physician. 2003 Jul 1;68(1):159-160.
Asthma management is generally determined by clinical features that do not necessarily correspond to the degree of airway inflammation. Sputum eosinophilia is an early indicator of lower airway inflammation, developing several weeks prior to clinical exacerbation of symptoms. Green and colleagues tested a novel approach of guiding asthma management by eosinophilia rather than symptoms or clinical measurements, such as peak flow readings.
The investigators recruited patients 18 to 75 years of age with asthma who were attending three specialist clinics in Great Britain. The patients were required to have no significant comorbidity (including smoking) or recent severe exacerbations and were assessed by their physicians as likely to adhere to the study protocols. All of the patients met criteria for moderate to severe asthma. During an initial two-week period, baseline function was assessed while receiving usual treatment. Seventy-four patients were then randomly assigned to management based on British Thoracic Society (BTS) guidelines or eosinophilia. In the BTS group, management was based on symptoms, peak expiratory flow, and use of beta agonists. In the eosinophilia group, management was determined by an algorithm designed to maintain the count below 3 percent with the minimum dose of anti-inflammatory treatment. All patients were assessed monthly for four months, then every two months for one year.
The groups were well matched. Thirty-four patients in each group completed the study. No patients withdrew because of side effects or poor control of symptoms. The eosinophilia-managed group had significantly fewer severe clinical exacerbations (35 compared with 109) and fewer rescue courses of oral corticosteroids (24 compared with 73) than the BTS-managed group. In the BTS group, 26 patients had more than one exacerbation during the year compared with 18 patients in the eosinophilia-managed group. The groups differed significantly in hospital admissions for asthma (one in the eosinophilia group and six in the BTS group). The groups did not differ in measures of quality of life, use of long-acting beta agonists, leukotriene antagonists, or mean dose of corticosteroids. The sputum eosinophil count was 63 percent lower during the year in the sputum management group.
The authors conclude that management directed at normalizing the sputum eosinophil count effectively reduces asthma exacerbations and hospital admissions. They call for further research and testing of management strategies targeting the basic inflammatory pathology of asthma, rather than the “downstream” symptom complexes. They anticipate that this approach could improve quality of life and reduce morbidity, mortality, and costs attributable to asthma.
Green RH, et al. Asthma exacerbations and sputum eosinophil counts: a randomised controlled trial. Lancet. November 30, 2002;360:1715–21.
editor's note: Physicians and patients find the current management of asthma frustrating. As with most recurrent conditions, patients frequently wait to see how bad an exacerbation is going to be before initiating or increasing treatment. Health professionals find this perplexing and are further frustrated by frequently having to make treatment decisions based on subjective reports of symptoms.“Just some wheezing” for some patients means a modest increase in symptoms, while for others it indicates impending respiratory failure. This study holds out the prospect of an earlier and more scientific monitoring system. Will patients come in for regular “eos counts?” Will self-testing kits become available? One benefit of such an advance would be a reduction in the “blame game” between patients and physicians. Whatever happens, the most vulnerable patients may be the least likely to benefit. As physicians, we must find ways to make advances understandable, acceptable, affordable, and accessible to those patients with the fewest resources. This takes more than money. It involves making patients feel safe, welcome, and cared for regardless of their situation or behaviors.—a.d.w.
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