Noninvasive liver disease assessment to identify portal hypertension: Systematic and narrative reviews supporting the AASLD Practice Guideline.

Background and aims: Portal hypertension is a serious complication of cirrhosis, which leads to life-threatening complications. 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 availability, noninvasive liver disease assessments to assess portal pressure, especially clinically significant portal hypertension (CSPH), are needed.

Approach and results: We conducted a systematic review of Ovid MEDLINE(R) 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, 2022. We included only studies in English that examined ≥50 patients in single liver disease etiologies, which compared noninvasive 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. Outcomes included measures of diagnostic test accuracy. Additionally, a narrative review of studies not eligible for the systematic review is also provided. Nine studies with 2492 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 FIB-4 (54% sensitivity and 73% specificity) had low accuracy measures. Imaging-based tests (transient elastography and shear wave elastography detection of liver stiffness measurement [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 noninvasive liver disease assessment 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.

Conclusions: While imaging-based noninvasive liver disease assessment appeared to have higher accuracy than blood-based tests to detect CSPH, only 9 studies fit the a priori established inclusion criteria for the systematic review. 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.