nonalcoholic fatty liver disease and liver fibrosis in bariatric patients: tehran obesity treatment study (tots)

Background: non-alcoholic fatty liver disease (nafld) has become a leading cause of chronic liver disease worldwide. we aimed to study this condition and liver fibrosis in bariatric patients at baseline using ultrasound, nafld fibrosis score (nfs), and fibrosis index-4 (fib-4). methods: adult patients with morbid obesity without other possible causes of liver pathology were evaluated. liver biopsy was performed in a subset of patients. diagnostic accuracy of tests was assessed using area under the receiver operating-characteristic curve (auroc). results: overall, 1944 patients with mean age of 38.3 ± 10.8 years and body mass index of 44.6 ± 6.4 kg/m comprised the study population. liver biopsy showed features of nafld in 70%; 60.3% had nonalcoholic fatty liver and 9.6% steatohepatitis. older age and higher transaminase levels were associated with higher nafld activity score. fibrosis was present in 23.3% with the majority having f1. ultrasound detected steatosis in 76.8%, with two-thirds having grade i to ii fatty liver. metabolic syndrome, hemoglobin a1c, age, and alanine transaminase were the strongest risk factors for fatty liver. ultrasound showed an auroc of 0.75 (95% confidence interval 0.63-0.86) for nafld with a sensitivity and specificity of 72.5% and 68.2%, respectively (cutoff of grade ii). for diagnosis of fibrosis, fib-4 had an auroc of 0.72 (0.58-0.86) with 93.3% sensitivity and 43.1% specificity (cutoff of 0.50). nfs failed to show a significant auroc curve for diagnosing fibrosis. conclusions: our findings confirmed a high prevalence of nafld in morbidly obese patients. despite this high prevalence, fibrosis was uncommon and low-grade. this study questions the use of current cutoffs for nfs and fib-4 in all patients.