Preferred Noninvasive Testing for Nonalcoholic Steatohepatitis

There has been an increased interest in the use of noninvasive tests (NITs) to identify advanced liver fibrosis in patients with nonalcoholic fatty liver disease (NALFD). The aim of our study was to define the change in tests' characteristics (sensitivity and specificity) of different combinations of NITs to detect advanced fibrosis in NAFLD.

We stratified NITs into first and second tiers and compared two different strategies of combining NITs to screen for advanced fibrosis in patients with NAFLD. One strategy was using NITs in parallel, and the other was using NITs sequentially. Within both of these strategies, there were two ways of interpreting the overall results. The first way was called "the AND rule," where a positive result required both individual test results to be positive. The second way was called "the OR rule," where a positive result required only one individual test to be positive. Accuracy of NITs was obtained from the literature search. Combined accuracy and likelihood ratio (LR) were calculated.

Combination testing with parallel and sequential order testing under the AND Rule resulted in overall higher specificity and LR+ then using the NITs alone. Specificity ranged from 0.91 to 0.99, and LR+ from 9.3 to 68.6. The subsequent use of MRE was associated with LR+ between 36 and 69. Sensitivity was higher with parallel and sequential order testing under the OR Rule. LR+ ranged from 1.4 to 7.5, and sensitivity from 0.82 to 0.98.

Screening for advanced fibrosis should be performed sequentially, with positive results confirmed by additional testing. Specificity and LR+ were highest when MRE was employed as the confirmatory test.