Specific airway resistance is a better outcome parameter in bronchial provocation testing compared to FEV₁ in patients with bronchial asthma

ABSTRACT

Objectives: Asthma is a chronic inflammatory disease characterized by airway hyperresponsiveness (AHR). A bronchial provocation test (BPT) is used to test for AHR. However forced expiratory volume in one second (FEV₁), used as outcome parameter is effort-related, in contrast to specific airway resistance (sRaw). This research was conducted to provide insight in the usefulness of sRaw as an outcome parameter in BPT. Methods: A total of 85 patients performing a BPT were included in the study. Bronchial reactivity was defined as the provocative dosage or provocative concentration causing a 20% decrease in FEV1 (PC-20) or a 100% increase in sRaw (PC+100). Results: No significant response in either FEV₁ or sRaw was found in 20 patients (24%). Twenty-nine patients (34%) only had a positive response for sRaw; 24 out of these 29 patients recognized their symptoms. 36 patients (42%) showed a positive response for both PC-20 and PC + 100. Conclusions: Twenty-nine patients (34%) showed a significant increase in sRaw without a fall in FEV₁. As performing sRaw is not a routine investigation, these patients are at risk of being excluded from a diagnosis of asthma. We suggest performing sRaw for patients without a fall in FEV₁ during BPT when they report recognizable symptoms.

KEYWORDS:

• Bronchial provocation test
• airway hyperresponsiveness
• asthma diagnosis
• airway resistance
• body plethysmography
• physiology

Declaration of interest

We hereby declare that none of the authors have received any financial support or other benefits from commercial sources for the work reported on in this manuscript; neither do they have any financial interest, which could create a potential conflict of interest.