An exploration of the implementation of FeNO testing and a FeNO-guided algorithm in primary care in England

<bold>Introduction:</bold> Fractional exhaled nitric oxide (FeNO) testing has been implemented in some areas of England, predominantly for asthma diagnosis. This study is nested in an ongoing randomised controlled trial investigating use of FeNO testing and a FeNO-guided algorithm, in primary care asthma reviews for ages 12 and over. <bold>Aims:</bold> Identify perceived barriers, facilitators, and contextual influences on implementing FeNO testing and a FeNO-guided algorithm in primary care asthma reviews. <bold>Methods:</bold> In-depth interviews were conducted with key stakeholders in relevant roles, including general practitioners, nurses, pharmacists, respiratory physiologists, patient representatives, and advocates. Snowball and theoretical sampling were used to maximise transferability. Data were thematically analysed. <bold>Findings:</bold> Findings suggest positive perceptions of FeNO and the FeNO-guided algorithm, particularly when algorithmic recommendations align with national guidance. Pre-selecting specific patient groups for the intervention and training assistants to conduct FeNO testing may reduce concerns about requiring additional funding and clinical time to implement the intervention. Clinicians perceive less experienced practitioners may have difficulty placing algorithm recommendations in the context of clinical assessments. Broader asthma training and support is needed to ensure optimal patient care and shared decision-making. Ensuring system interoperability with electronic medical records may aid implementation. <bold>Conclusions:</bold> Strategies to select patients most likely to benefit, harness funding, enhance system interoperability and ensure appropriate training, could maximise sustained implementation.