Usual interstitial pneumonia (UIP) is the histopathologic hallmark of idiopathic pulmonary fibrosis (IPF), the prototypical interstitial lung disease (ILD). Diagnosis of IPF requires a typical UIP pattern identified by high-resolution chest CT or lung sampling. A genomic classifier for UIP has been developed to predict histopathologic UIP using lung samples obtained by bronchoscopy.
Perform a systematic review to evaluate genomic classifier testing in the detection of histopathologic UIP to inform new American Thoracic Society (ATS), European Respiratory Society (ERS), Japanese Respiratory Society (JRS), and Asociación Latinoamericana del Tórax (ALAT) guidelines.
Medline, Embase and Cochrane Central Register of Controlled Trials were searched through June 2020. Studies that enrolled patients with ILD and reported the use of genomic classifier testing were selected for inclusion. Data were extracted and pooled across studies via meta-analysis. The quality of the evidence was appraised using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.
Genomic classifier testing had a sensitivity of 68% (95% CI 55-73%) and a specificity of 92% (95% CI 81-95%) in predicting the UIP pattern in ILD. Confidence in an IPF diagnosis increased from 43% to 93% in one cohort and from 59% to 89% in another cohort. Agreement in categorical IPF and non-IPF diagnoses measured using a concordance coefficient was 0.75 and 0.64 in the two cohorts. The quality of evidence was moderate for test characteristics and very low for both confidence and agreement.
Genomic classifier testing predicts histopathologic UIP in patients with ILD with a specificity of 92% and improves diagnostic confidence; however, sensitivity is only 68% and testing is not widely available.