Relationship Between Thoracic CT Severity Score and Scadding Staging With PFT, DLCO, and 6MWT in Patients With Sarcoidosis.

BACKGROUND

Chest computed tomography (CT) is widely used in the diagnosis and follow-up of diffuse parenchymal lung diseases like sarcoidosis. This study investigated the relationship between the Thoracic CT Severity Score (TCTSS) and parameters from pulmonary function tests (PFTs), diffusing capacity for carbon monoxide (DLCO), and the 6-min walk test (6MWT) in sarcoidosis patients, comparing its utility to the radiograph-based Scadding staging system.

METHODS

This retrospective study analyzed data from 60 sarcoidosis patients with concurrent chest radiograph, CT, PFT, DLCO, and 6MWT results. Patient demographics, TCTSS, Scadding stage, PFT parameters (forced expiratory volume in one second [FEV1], forced vital capacity [FVC], FEV1/FVC, PEF, and FEF25-75), DLCO, DLCO/VA, and 6MWT parameters (initial SpO2, final SpO2, desaturation percentage, distance, and predicted distance percentage) were collected. Correlations between these functional parameters and both TCTSS and Scadding stages were analyzed to compare the strengths of the two staging systems.

RESULTS

TCTSS showed moderate negative correlations with FEV1% (r = -0.44, p < 0.001), FVC% (r = -0.477, p < 0.001), DLCO (r = -0.522, p < 0.001), final 6MWT SpO2 (r = -0.417, p=0.001), and 6MWT% (r = -0.511, p < 0.001). Weaker correlations were observed between TCTSS and initial SpO2, desaturation, and 6MWT distance. The Scadding stage also demonstrated negative correlations with these parameters, although generally weaker for FEV1% and FVC%. TCTSS exhibited stronger negative correlations with FEV1%, FVC%, DLCO, and 6MWT% compared to Scadding staging. Conversely, the Scadding stage correlated more strongly with FVC (liters), FEV1 (liters), FEV1/FVC, DLCO/VA, initial SpO2, final SpO2, and 6MWT distance. Desaturation showed similar low-to-moderate positive correlations with both staging systems.

CONCLUSIONS

This study demonstrates that TCTSS significantly correlates with most functional parameters, exhibiting stronger correlations for key measures (FVC%, FEV1%, DLCO, and 6MWT%) compared to the Scadding staging system. TCTSS is a valuable tool that warrants consideration in the follow-up of sarcoidosis patients. Our findings suggest that TCTSS could serve as a potential alternative or complementary system to the Scadding classification, potentially informing the development of a modified combined staging approach. Larger, multicenter studies are necessary to confirm these findings and further explore the role of TCTSS in sarcoidosis management.