There are two interesting publications from Schneider et al in Germany:
1. Diagnosing asthma in general practice with portable exhaled nitric oxide measurement – results of a prospective diagnostic study
This is a prospective diagnostic study with 160 patients attending 10 general practices for the first time with complaints suspicious of obstructive airway disease Patients were referred to a lung function laboratory for diagnostic investigation. The index test was FENO measured with NIOX MINO. The reference standard was spirometry (FEV1/VC) and/or results of bronchial provocation with methacholine to determine bronchial hyper-responsiveness (BHR) in the event of inconclusive spirometric results.
Asthma could be ruled in with FENO > 46 ppb. Mild and moderate to severe asthma could be ruled out with FENO < 12 ppb. FENO measurement might be reasonable with respect to the time consuming procedure of bronchial provocation, which carries also some risk of severe bronchospasm.
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2. Diagnostic accuracy of spirometry in primary care
This is a cross sectional diagnostic study of 219 adult patients attending 10 general practices for the first time with complaints suspicious for obstructive airway disease . All patients underwent spirometry to evaluate the sensitivity, specificity and predictive values of spirometry for the diagnosis of COPD and asthma. In the event of inconclusive results, bronchial provocation was performed to determine bronchial hyper-responsiveness (BHR). The conclusion is that COPD can be estimated with high diagnostic accuracy using spirometry. It is also possible to rule in asthma with spirometry. However, asthma can not be ruled out only using spirometry. This diagnostic uncertainty leads to an overestimation of asthma presence. Patients with inconclusive spirometric results should be referred for nitric oxide (NO) – measurement and/or bronchial provocation if possible to guarantee accurate diagnosis.