Diagnosis of asthma: the challenge goes on

• Diagnostics
• letter to editor
• epidemiology
• management/control
• mechanisms

Recently, Löwhagen has published a very interesting review article in the Journal of Asthma [1]. The author introduces 8 new theories related to inflammation, hyper responsiveness, obstruction and symptoms of asthma. Moreover, Löwhagen highlights some actions that represent advances for the diagnostic investigation [1]. All theories are very relevant. However, we would like to emphasize some aspects corresponding to theory 4. The issue addressed by theory 4 is the patient’s inability to make adequate forced expirations, a fundamental requirement to perform spirometry. This is very possibly a big challenge for clinicians because it involves in general extreme age groups like preschool children and elderly. Although spirometry is one of the most useful tools for asthma investigation [2], when it is not performed properly, it becomes meaningless. This is not uncommon.

So, how is it possible to do the diagnosis of asthma in patients unable to perform a proper spirometry? Löwhagen suggests that in these cases, spirometry should be supplemented by non-effort-demanding methods, such as body plesthysmography or impulse oscillometry (IOS) [1]. It is tempting to look favourably upon IOS as an additional or alternative test for spirometry. IOS is a simple method, which demands minimal collaboration and allows an evaluation of pulmonary function through the resistance and reactance of airways [3]. Moreover, IOS can detect alterations in small airways [4], suggesting its utility for diagnosing mild asthma. Mild asthma cases are surely the most frequently underdiagnosed ones. But, how accurate is IOS at recognizing asthma? Apparently, this question has no clear answer yet. We have been reviewing literature systematically in these past years and what we have observed is that the studies are very heterogeneous, either in terms of methods or data of sensitivity and specificity. Some diagnostic endpoints, like the positive and negative predictive values have not been well explored. Although IOS has been determined to be pointed as a method of distinguishing asthmatic from non-asthmatic patients, the evidence available regarding IOS accuracy is still poorly defined. A deeper knowledge about the diagnostic properties of IOS can reduce the amount of incorrect diagnoses and increase the success rate in treating asthma.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.