Diagnostic agreement of usual interstitial pneumonia (UIP) on chest CT between chest radiologists using current guidelines

Introduction: Current guidelines propose criteria to diagnose a UIP pattern on chest CT and recommend that a definite UIP pattern on chest HRCT obviates the need for biopsy. However, the criteria have not been prospectively validated. Objective: To assess the agreement in the diagnosis of UIP pattern between chest radiologists when applying the ATS/ERS/JRS/ALAT Guidelines. Methods: Two chest radiologists at a tertiary academic center in Canada reviewed 117 good quality chest CT scans of patients with interstitial lung diseases to determine the presence of a UIP pattern. As per the guidelines, chest radiologists diagnosed: 1) Definite UIP and 2) Not definite UIP pattern -which included possible UIP and inconsistent UIP patterns. We assessed their agreement in the diagnosis of UIP patterns, as well as in the diagnosis of reticulation, honeycombing, and the location of abnormalities. Results: Agreement between chest radiologists in the diagnosis of Definite UIP was 66%; for Not definite UIP pattern was 82%; and overall agreement for UIP patterns was 74% (Kappa 0.48; moderate agreement). Agreement in the diagnosis of reticulation was 95% (Kappa 0.64; substantial agreement), and of honeycombing was 85% (Kappa 0.70; substantial agreement). Agreement on the subpleural predominance of abnormalities was 82% (Kappa 0.39; fair agreement), and in basilar predominance 73% (Kappa 0.46; moderate agreement). Conclusions: Agreement in the diagnosis of UIP by chest radiologists using the criteria proposed by current guidelines may not be high enough in the real clinical setting to obviate the need for lung biopsy.