Barrier to using APRI and GPR as identifiers of cystic fibrosis liver disease

Cystic fibrosis-associated liver disease (CFLD) is the third most common cause of death in cystic fibrosis (CF). Poor ability to identify early, non-cirrhotic liver disease hampers interventions to mitigate complications associated with CFLD and potential early therapies that may halt the progression of cirrhosis. Liver fibrosis indices, such as APRI, FIB-4, and GPR, are minimally invasive biomarkers that may be useful for the detection and monitoring of CFLD. However, variability in the upper limit of normal values used in these calculations makes it difficult to compare results across research studies and identify appropriate indices cutoffs. Previously published APRI and GPR values are re-calculated using the same upper limit of normal values as recently published data on APRI and GPR, highlighting the importance of standardized upper limit of normal values for calculating liver fibrosis indices in CFLD detection and monitoring.