The use of a direct bronchial challenge test in primary care to diagnose asthma: an observational real-life study

Abstract

Background: Asthma is diagnosed based on respiratory symptoms and confirmed variable expiratory airflow limitation. Many asthmatics in primary care have mild asthma and lack airflow obstruction. If expiratory airflow limitation variability cannot be determined using spirometry, a bronchial challenge test (BCT) can be used to confirm or exclude the diagnosis of asthma. Traditionally, BCT is only performed in secondary care. Aim: We hypothesize that the use of a BCT is safe and feasible in a well-trained primary care diagnostic centre and increases diagnostic accuracy while reducing the number of diagnostic referrals to secondary care. Method: Star-shl (Rotterdam, The Netherlands) is a primary care diagnostic centre where direct BCTs (using histamine) are carried out according to ERS/ATS guidelines. Patients ≥ 16 years can be referred for BCT after diagnostic spirometry. We retrospectively analysed data obtained over a 5 year period of BCT at Star-shl. Results: 998 patients - mean age 43.2 year (SD 14.87), 64% female - underwent a histamine provocation test. No adverse events occurred during these tests. For the diagnostic analysis we examined 645 patients who performed both spirometry and BCT at Star-shl. 58% (376/645) had a positive BCT. If this result was accompanied with a history of asthma symptoms an accurate diagnosis could be made. Asthma could be excluded in the other patients (269/645). Conclusion: Diagnostic referrals to secondary care can be reduced by using BCT in primary care as 58% of our patients showed airway hyperresponsiveness. Moreover, BCT proved to be safe and feasible at this centre.