Diagnostic Accuracy and Optimal Cut-off of Controlled Attenuation Parameter for the Detection of Hepatic Steatosis in Indian Population

Abstract

Background and aims: Ultrasound of the liver is not good to pick up mild steatosis. Controlled attenuation parameter (CAP) evaluated in transient elastography (FibroScan) is widely available in India. However, data regarding the diagnostic accuracy and optimal cut-off values of CAP for diagnosing hepatic steatosis are scarce in Indian population. MRI-PDFF is an accurate technique for quantifying hepatic steatosis. Thus, this study examined the diagnostic accuracy and optimal cut-off values of CAP for diagnosing steatosis with MRI-PDFF as reference standard.

Methods: A total of 137 adults underwent CAP and MRI-PDFF measurements prospectively. A subset of participants (n = 23) underwent liver biopsy as part of liver transplantation evaluation. The optimal cut-off values, area under the receiver operating characteristic (AUROC) curves, sensitivity, and specificity for CAP in detecting MRI-PDFF ≥5% and ≥10% were assessed.

Results: The mean age and body mass index (BMI) were 44.2 ±10.4 years and 28.3 ±3.9 kg/m², respectively. The mean hepatic steatosis was 13.0 ±7.7% by MRI-PDFF and 303 ±54 dB/m by CAP. The AUROC of CAP for detecting hepatic steatosis (MRI-PDFF ≥5%) was 0.93 (95% CI, 0.88-0.98) at the cut-off of 262 dB/m, and of MRI-PDFF ≥10% was 0.89 (95% CI, 0.84-0.94) at the cut-off of 295 dB/m. The CAP of 262 dB/m had 90% sensitivity and 91% specificity for detecting MRI-PDFF ≥5%, while the CAP of 295 dB/m had 86% sensitivity and 77% specificity for detecting MRI-PDFF ≥10%.

Conclusions: The optimal cut-off of CAP for the presence of liver steatosis (MRI-PDFF ≥5%) was 262 dB/m in Indian individuals. This CAP cut-off was associated with good sensitivity and specificity to pick up mild steatosis.

Keywords: ALT, alanine aminotransferase; AST, aspartate aminotransferase; AUROC, area under receiver operating characteristics; BMI, body mass index; CAP, controlled attenuation parameter; India; LSM, liver stiffness measurement; MRI-PDFF; MRI-PDFF, magnetic resonance imaging-proton density fat fraction; MRS, magnetic resonance spectroscopy; NAFLD, non-alcoholic fatty liver disease; NPV, negative predictive value; PPV, positive predictive value; TE, transient elastography; biopsy; liver steatosis; non-alcoholic fatty liver disease.

Figure 1

Derivation of the study cohort. In total, 168 participants were potentially eligible, and 18 subjects were excluded because of various reasons as shown in the figure. Among 150 eligible participants, 10 and 3 participants were excluded for missing CAP and MRI PDFF data, respectively. A total of 137 participants were finally analyzed.

Figure 2

Distribution of CAP measurements stratified by the amount of hepatic steatosis. CAP values increased with increase in liver fat content assessed by MRI-PDFF (Kruskal–Wallis test P < 0.001): MRI PDFF <5.0%, n = 22; MRI PDFF 5.0–10.0%, n = 35; MRI PDFF ≥10.0%, n = 80.

Figure 3

Receiver operating curves (A) for detecting liver steatosis ≥5%, (B) for detecting liver steatosis ≥10%, and (C) for detecting liver steatosis ≥20% (steatosis defined by MRI-PDFF).

Supplementary figure 1

Correlation of CAP and MRI-PDFF.