Non-invasive liver disease assessment to identify portal hypertension: A systematic review supporting the AASLD Practice Guideline.

INTRODUCTION: Portal hypertension is a serious complication of cirrhosis, which leads to life-threatening complications. Hepatic venous pressure gradient (HVPG), a surrogate of portal pressure, is the reference standard test to assess the severity of portal hypertension. However, since HVPG is limited by its invasiveness and by its availability, non-invasive liver disease assessments (NILDAs) to assess portal pressure, especially clinically significant portal hypertension (CSPH), are needed.

METHODS: We conducted a systematic review of Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, and Daily, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus from each database's inception to April 22 nd , 2022. We included only studies in English that examined ≥50 patients in single liver disease etiologies which compared non-invasive tests (blood, and/or imaging) to HVPG for predicting clinically significant portal hypertension (CSPH; defined as HVPG ≥10 mm Hg) in patients with chronic liver disease (this therefore limited the number of studies that could be included). Outcomes reported included measures of diagnostic test accuracy. Additionally, a narrative review of studies not eligible for the systematic review is also provided.

RESULTS: Nine studies with 2,492 patients met the inclusion criteria. There was substantial heterogeneity with regard to liver disease studied and cutoff values used to detect CSPH. Blood based tests, including aspartate to platelet ratio index (APRI) (56% sensitivity and 68% specificity) and fibrosis-4 (FIB-4) (54% sensitivity and 73% specificity) had low accuracy measures. Imaging based tests (transient elastography (TE) and shear wave elastography detection of liver stiffness (LSM)) had better accuracy, but also had substantial variation; at 15 kPa, TE sensitivity was 90%-96% and specificity was 48%-50% while at 25 kPa, its sensitivity and specificity were 57%-85% and 82%-93%, respectively. The narrative review suggested that imaging based tests are the best available NILDA to detect CSPH, CSPH is highly unlikely to be present at an LSM ≤15 kPa and likely to be present at an LSM ≥25 kPa.

CONCLUSION: While imaging-based NILDA appeared to have higher accuracy than blood-based tests to detect CSPH, only 9 studies fit the a priori established inclusion criteria for the SR. In addition, there was substantial study heterogeneity and variation in cutoffs for LSM to detect CSPH, limiting the ability to establish definitive cutoffs to detect CSPH.