Blood Test is Better Than a Liver Biopsy for Biliary Atresia

A recent study (L Yang et al. Hepatology 2018; 68: 2069-72) confirms the utility of Serum Matrix Metalloproteinase-7 (MMP-7) as a biomarker for biliary atresia (BA). The authors studied MMP-7 among healthy controls (n=72 with 54 <6 months) and among 135 with cholestasis (75 with BA, 60 with non-BA).  BA samples were taken at a median age of 54 days.

Key findings:

  • Median concentration for MMP-7 was 2.86 ng/mL in healthy controls, 11.47 ng/mL for non-BA cholestasis, and 121.1 ng/mL for BA.
  • Using a cutoff value of 52.85 ng/mL, the diagnostic sensitivity and specificity were 98.67% and 95.0% respectively.
  • The AUC for MMP-7 in BA was 0.99 compared for AUC for GGT of 0.72.  The sensitivity and specificity for GGT was much lower at 64% and 72% respectively with a cutoff of 314 U/L.
  • The predictive value for MMP-7 was particularly impressive, 74 of 75 BA  subjects were correctly identified as having BA.  Only 3 non-BA patients were incorrectly assigned a BA diagnosis based on MMP-7 values.
  • The authors noted that MMP-7 testing indicates that there are no substantial changes in its values for normal subjects extending to 54 years of age.
  • One limitation the authors note is the relatively small number of patients with non-BA syndromatic intrahepatic cholestasis which made up less than 30% of their non-BA cohort.  Thus, more testing in specific populations is needed.

My take: The diagnostic performance of MMP-7** appears to be superior to that of a liver biopsy (though this was not directly compared in this study) in predicting BA and could obviate the need for most liver biopsies in infants with cholestasis.  Those with high MMP-7 values would proceed directly to intraoperative cholangiogram with possible hepatoportojejunostomy. Those with non-BA MMP-7 values and persistent cholestasis could undergo additional investigation with genetic panels and/or other metabolic/infectious testing.

**This assay is likely to be commercially-available in the coming weeks according to a colleague at Cincnnati Children’s Hospital.  The expectation is an approximagely 2-day turnaround.

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