Adenosine monophosphate is not superior to histamine for bronchial provocation test for assessment of asthma control and symptoms.

ABSTRACT

BACKGROUND: Adenosine monophosphate (AMP) may reflect airway inflammation and hyperresponsiveness, but relationship between AMP and histamine (His, a conventional stimulus) bronchial provocation test (BPT) in asthma is not fully elucidated. OBJECTIVES: To compare both BPTs and determine their utility in reflecting changes of asthmatic symptoms. METHODS: BPTs were performed in a cross-over fashion, at 2-4 day intervals. Cumulative doses eliciting 20% FEV1 fall (PD20 FEV1 ), diagnostic performance and adverse events (AEs) were compared. Patients with PD20 FEV1 lower than geometric mean were defined as responders, otherwise poor responders. Patients with uncontrolled and partly controlled asthma, who maintained their original inhaled corticosteroids therapy, underwent reassessment of airway responsiveness and asthmatic symptoms 3 and 6 months after. RESULTS: Nineteen uncontrolled, 22 partly controlled and 19 controlled asthmatic patients and 24 healthy subjects were recruited. Lower PD20 FEV1 geometric means were associated with poorer asthma control in His-BPT (0.424 µmol vs 1.684 µmol vs 3.757 µmol), but not AMP-BPT (11.810 µmol vs 7.781 µmol vs 10.220 µmol). Both BPTs yielded similar overall diagnostic performance in asthma (area under curve 0.842 in AMP-BPT vs 0.850 in His-BPT). AEs, including wheezing and tachypnea, were similar and mild. Ten patients with uncontrolled and 10 partly controlled asthma were followed-up. At months 3 and 6, we documented an increase in PD20 FEV1 -AMP and PD20 FEV1 -His, which did not correlate with reduction asthmatic symptom scores. This overall applied in responders and poor responders of AMP-BPT and His-BPT. CONCLUSION: Despite higher screening capacity of well-controlled asthma, AMP-BPT confers similar diagnostic performance and safety with His-BPT. AMP-BPT might not preferentially reflect changes asthmatic symptoms.