Objective Making the diagnosis of asthma is challenging. Guidelines recommend that clinicians identify a group at ‘high probability’ of asthma. High probability, however, is not numerically defined giving rise to uncertainty. The aim of this work was to build consensus on what constitutes a high probability of asthma in primary care. High probability was defined as the probability threshold at which there is enough information to make a firm diagnosis of asthma, and a subsequent negative test would not alter that opinion (assumed to be a false negative).
Design Mixed-methods study.
Setting A consensus workshop using modified nominal group technique was held during an international respiratory conference.
Participants International conference attendees eligible if they had knowledge/experience of working in primary care, respiratory medicine and spoke English.
Methods Participants took part in facilitated discussions and voted over three rounds on what constituted a high probability of asthma diagnosis. The workshop was audio-recorded, transcribed and qualitatively analysed.
Results Based on final votes, the mean value for a high probability of asthma in primary care was 75% (SD 7.6), representing a perceived trade-off between limiting the number of false positives (more likely if a lower threshold was used) and pragmatism on the basis that first-line preventive therapies (ie, low-dose inhaled corticosteroids) are relatively low risk. The need to review response to treatment was strongly emphasised for detecting non-responders and reviewing the diagnosis.
Conclusion A consensus probability of 75% was the threshold at which the primary care participants in this workshop felt confident to establish the diagnosis of asthma, albeit with the caveat that a review of treatment response was essential. Contextual factors, including availability and timing of tests and the ease with which patients could be reviewed, influenced participants’ decision making.
- primary care
- qualitative research
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Contributors HP, LD and ASc conceived the idea for this work, supported by ASh and SL. All authors contributed to the interpretation of the findings. The paper was drafted by LD and HP and revised after feedback from all other authors. All authors have seen and approved the final version.
Funding This work was supported by the Chief Scientist Office (grant number CAF/17/01).
Competing interests LD and HP are on the British Thoracic Society (BTS)/Scottish Intercollegiate Guideline Network (SIGN) asthma guideline development committee. ASh has previously served on the BTS/SIGN Asthma Guideline Committee and currently serves on Global Initiative for Asthma’s Scientific Committee. ASc is a member of the Committee of the German National Asthma Guideline (Nationale VersorgungsLeitlinie Asthma (NVL) Asthma).
Patient and public involvement The programme of research benefits from the involvement of users, both patients and professionals, who have provided feedback on the study design, informational material and acted as co-applicants on grants and members of the project steering group.
Patient consent for publication Not required.
Ethics approval The study protocol was reviewed and approved by the University of Edinburgh sponsor (number: AC19047), which recommended that no further ethical review was required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available. We do not have consent to share the primary data collected with other researchers.
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