Diagnostic Accuracy of Serum Matrix Metalloproteinase-7 As a Biomarker of Biliary Atresia in a Large North American Cohort

Background & Aims: High levels of serum matrix metalloproteinase-7 (MMP-7) have been linked to biliary atresia (BA), with wide variation in concentration cutoffs. We investigated accuracy of serum MMP-7 as a diagnostic biomarker in a large North American cohort. Approach & Results: MMP-7 was measured in serum samples of 399 cholestatic infants in the Prospective Database of Infants with Cholestasis study of the Childhood Liver Disease Research Network, 201 infants with BA and 198 with non-BA cholestasis (age median: 64 and 59 days, p=0.94). MMP-7 was assayed on antibody-bead fluorescence (single-plex) and time resolved-fluorescence energy transfer (TR-FRET) assays. Discriminative performance of MMP-7 was compared with other clinical markers. On the single-plex assay, MMP-7 generated an area under receiver operating curve (AUROC) of 0.90 (confidence interval [CI] 0.87-0.94). At cutoff 52.8 ng/mL, it produced sensitivity=94.03%, specificity=77.78%, positive predictive value=64.46%, and negative predictive value=96.82% for BA. AUROC for gamma-glutamyl transferase (GGT)=0.81 (CI 0.77-0.86), stool color=0.68 (CI 0.63-0.73), and pathology=0.84 (CI 0.76-0.91). Logistic regression models of MMP-7 with other clinical variables individually or combined showed an increase for MMP-7+GGT AUROC to 0.91 (CI 0.88-0.95). Serum concentrations produced by TR-FRET differed from single-plex, with optimal cutoff of 18.2 ng/mL. Results were consistent within each assay technology and generated similar AUROCs. Conclusions: Serum MMP-7 has high discriminative properties to differentiate BA from other forms of neonatal cholestasis. MMP-7 cutoff values vary according to assay technology. Using MMP-7 in evaluation of cholestatic infants may simplify diagnostic algorithms and shorten time to hepatoportoenterostomy.