HRCT Phenotypes in Sarcoidosis: association with pulmonary function, inflammatory markers and organ involvement

STUDY QUESTION Are the Delphi derived HRCT phenotypes associated with pulmonary function tests, inflammatory markers and organ involvement at presentation in newly diagnosed sarcoidosis patients? STUDY DESIGN AND METHODS This cross-sectional study was conducted in two non-academic teaching hospitals between 2015 and 2020. Patients with a new diagnosis of sarcoidosis with baseline PFT and (HR)CT were included. CT images were systematically scored according to the Delphi HRCT phenotypes, including seven individual phenotypes (P1-P7) divided into two subgroups: “non-fibrotic” phenotypes (NFP) (P1-P4) and “likely-to-be fibrotic” phenotypes (FP) (P5-P7); and a “rest” group (not classifiable) and “null” group (no abnormalities) were identified. Differences in PFT, inflammatory markers and organ involvement were compared across phenotypes and subgroups. Logistic and linear regression was used to adjust for potential confounders. RESULTS A total of 281 patients were included: 160 in the “NFP”, 34 in the “FP”, 8 in the “rest” and 79 in the “null” subgroup. Fibrotic phenotypes were associated with an obstructive pattern and diffusion impairment compared to NFP, with phenotypes P5 and 6 characterized by a restrictive spirometric pattern and moderate - severe diffusion impairment, and phenotype 7 characterized by an obstructive pattern and mild diffusion impairment. No consistent or clinically relevant associations were observed between CT phenotypes and inflammatory markers or organ involvement. ANSWER TO THE QUESTION An association is for the first time demonstrated between the Delphi HRCT phenotypes and baseline PFT in newly diagnosed sarcoidosis, supporting the value of these phenotypes towards a more established CT classification.