The clinical significance of CT-Thorax in the assessment of difficult to treat Asthma

Background: CT scan of thorax often forms part of the diagnostic algorithm of difficult to treat asthma (DTA). However its diagnostic value and effect on patient management remained largely undetermined. Aim: To assess the diagnostic value of CT-Thorax in the management of DTA. Methods: Unselected patients with DTA presenting to a tertiary severe asthma centre were put through a systematic assessment protocol and undertook high resolution CT-thorax. Radiological diagnoses in addition to demographics and asthma related clinical outcomes were explored using standard statistics. Results: A cohort of 290 patients were included in the study (mean age 51±14.2 years, 62.1% females, Caucasians 74.8%, non-smokers 57.8%, BMI 31.7±7.6 kg, ACQ6 2.9±1.6, %predicted FEV 1 72.8±26, FeNO 51.62±44.8 ppb, blood eosinophils 452±459 cell/µl, severe exacerbations 5.9±4.3 per annum, maintenance oral corticosteroids 30%). The observed CT abnormalities were bronchial wall thickening 76.1%, bronchiectasis 49.4%, ground-glass 34.7%, mucus plugging 28.1%, air-trapping 29.2%, central bronchiectasis 7.2%, emphysema 5.5%, in addition to other less common diagnoses (e.g. eosinophilic pneumonia). We observed no significant difference between the bronchiectasis and non-bronchiectasis groups in terms of annual severe exacerbations (7.1±5.1 vs 6.0±3.9, p=0.1 respectively), lung function, blood eosinophils or FeNO. Conclusions: Radiological abnormalities were prevalent in DTA patients and may have impact on patient management prompting the need to consider CT-thorax as an integral part of DTA diagnostic algorithm. Further results on dynamic CT findings will be provided in the conference.