Safety of sputum monitoring in a severe asthma population - The Manchester severe asthma team experience

With its key role as marker of airway inflammation and steroid-responsiveness, sputum eosinophil monitoring is increasingly employed in clinical asthma services. There are concerns about its use in severe asthma due to perceived risk of adverse reactions. Manchester Severe Asthma Service has been using sputum monitoring in clinical decision-making since 2006. Here we report the safety data in our patients that have been monitored to date. Sputum samples were obtained either spontaneously or after induction with nebulised hypertonic saline and processed with DTT following standard method, with 400 non-squamous cells counted as part of the differential cell count. Sputum sampling has been attempted on 1400 occasions in 770 patients to date. In 78% of cases a spontaneous sample was obtained. Sputum induction was successful in 76% of the remaining cases. We were unable to obtain analysable samples in 5% of all cases. A higher success rate for spontaneous sampling was observed in subsequent (80%) compared to first-time procedures (70%) ( p 1 (7%); bronchoconstriction requiring rescue medication (13%); VCD (4%). Direct involvement of a clinician was required in 9% of induced cases, typically to authorise if low FEV 1 , or help with management where initial rescue medication was insufficient. Sputum induction in a tertiary severe asthma service is safe, effective and has an excellent yield, with physician9s involvement only necessary in 8.5% of cases. This supports the wider adoption of sputum monitoring in severe asthma populations, where adequate training and personnel are available.