Advantages Of Spirometry To Differentiate Asthma From COPD - SCHILLER

Advantages Of Spirometry To Differentiate Asthma From COPD

Asthma and COPD are clearly differentiated… on paper. But in real life, diagnosing one or the other isn’t as straightforward as the books say. It is very common for patients to present symptoms that are very common in both diseases. 


The study “Diagnostic differentiation between asthma and COPD in primary care using lung function testing” focused on finding a more functional way to diagnose patients correctly. This clinical trial demonstrated the value of performing lung function tests from first contact. 


Asthma vs. COPD 

The authors of the clinical trial conducted a cross-sectional study in 10 general practitioner offices in the Netherlands. They compared patients diagnosed with asthma, patients diagnosed with COPD and subjects without data of pulmonary obstruction of airways. Individuals with pre-existence of asthma, COPD or other airway diseases were excluded. 


* A total of 532 subjects participated, whose respiratory symptoms and lung function were thoroughly examined. 

* They were instructed to discontinue the use of bronchodilators for a specific period of hours before undergoing pulmonary function tests. 

* Pulmonary function tests included pre- and post-bronchodilator spirometry, DLCO measurements, and bronchial hyperresponsiveness. 

* Two chest physicians assessed if patients had asthma or COPD. 

* To differentiate asthma from COPD, multivariate logistic regression was analyzed considering three scenarios: only the patient’s history, the available diagnosis of the first contact physician, and the diagnoses available for secondary care. 

* For each scenario, the curve (ROC) of the operating characteristic of the receiver and the area below the curve (AUC) was calculated considering the evaluation of chest physicians as a gold standard. 

* All tests were performed by certified technicians at a hospital-based lung function laboratory. 

* Researchers used standards of the American Thoracic Society of 1994. 

* They also calculated the predicted normal lung function values for FEV1 based on the values of the European Community for Coal and Steel 




Of the total participants, 84 subjects were diagnosed with asthma, 138 with COPD and 310 showed no chronic respiratory disease. In the scenario that included only patient history data, the ROC characteristics of the model showed an AUC of 0.84 (95% CI 0.78–0.89) to differentiate between asthma and COPD. 

By including available primary care diagnoses (that is to say, pre- and post-bronchodilator spirometry), the AUC increased to 0.89 (95% CI 0.84–0.93, P = 0.020). When the most advanced diagnostic tests obtained in secondary care were added, the AUC remained at 0.89 (95% CI 0.85–0.94, P = 0.967). 



The authors of this clinical trial concluded that primary care physicians should be able to differentiate asthma from COPD as long as, in addition to considering the relevant medical history of patients, they perform postbronchodilator spirometry. For this reason, they consider that training to perform spirometry should be mandatory for family doctors.  

It is evident that spirometry is a very useful test to differentiate asthma from COPD, which allows a timely diagnoses and treatment for the patient. If we add to this the advantages of ultrasonic technology offered by our ultrasonic spirometer, SpiroScout, it is clear that it is a great option. 

SpiroScout provides reliable tests because it measures even very low flows, and this can make the work of primary care physicians easier, since it is not necessary for them to repeat the maneuver. And it can also improve the quality of life of the patient, who can obtain accurate and early diagnoses. 

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