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Diagnosing asthma: comparisons between exhaled nitric oxide measurements and conventional tests
Andrew D Smith1, Jan O Cowan, Sue Filsell
1Dunedin School of Medicine, University of Otago Medical School, Dunedin, New Zealand.
American Journal of Respiratory and Critical Care Medicine
|December 3, 2003
Summary
Exhaled nitric oxide (FE(NO)) and sputum eosinophils are superior diagnostic tools for asthma compared to traditional tests. These methods offer higher accuracy in identifying asthma, with FE(NO) being particularly convenient.
Area of Science:
- Pulmonology
- Diagnostic Medicine
- Allergy and Immunology
Background:
- Current asthma diagnosis relies on tests for variable airflow obstruction and bronchodilator/corticosteroid response.
- Airway inflammation assessment via exhaled nitric oxide (FE(NO)) and induced sputum analysis is increasingly recognized.
- Systematic comparisons of diagnostic utility for these asthma assessment methods are lacking.
Purpose of the Study:
- To systematically compare the diagnostic accuracy of conventional asthma tests with FE(NO) and induced sputum analysis.
- To evaluate the utility of peak flow, spirometry, and steroid response in asthma diagnosis.
- To determine the most effective diagnostic approach for asthma.
Main Methods:
- A comprehensive series of diagnostic tests were performed on 47 patients with asthma-suggestive symptoms.
- Sensitivities and specificities were calculated for peak flow, spirometry, and steroid response.
- Comparisons were made against FE(NO) measurements and sputum cell counts.
Main Results:
- Conventional tests showed low sensitivity (0-47%) for asthma diagnosis.
- FE(NO) (88%) and sputum eosinophils (86%) demonstrated significantly higher sensitivities.
- Steroid trials did not improve the diagnostic accuracy of conventional tests.
Conclusions:
- FE(NO) measurements and induced sputum analysis are superior to conventional methods for diagnosing asthma.
- FE(NO) is particularly advantageous due to its speed and ease of performance.
- These advanced methods provide greater diagnostic accuracy for asthma assessment.