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NAFLD Fibrosis Score inaccurate in patients with elevated BMI
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BOSTON — Fibrosis in patients with a BMI greater than 35 was not accurately measured by the NAFLD Fibrosis Score in a study presented at The Liver Meeting.
Researchers assessed the accuracy of the score — defined in a 2007 study by Angulo et al — in a cohort of 169 patients preparing for Roux-en-Y gastric bypass who had BMI greater than 40 or BMI above 35 with underlying complications. Patients were classified as Low (no significant fibrosis), Indeterminate, or High (significant fibrosis) depending on each patient’s calculated NAFLD Fibrosis Score. Liver biopsy also was performed on each patient, and investigators compared these results with those of the fibrosis score calculations.
“This [score] took six different clinical parameters: Age, BMI, [diabetes status], AST/ALT ratio, platelet count and albumin,” researcher Iain H. McKillop, PhD, research group director in the department of surgery at Carolinas Medical Center in Charlotte, N.C., told Healio.com. “If you put these through an algorithm, you can accurately calculate the probability of a patient having fibrosis. … Because one of those factors is BMI, my colleagues who are bariatric surgeons were very interested to know whether the same thing applied in a patient population that has much higher BMI than normal.”
Across the cohort, 68 patients were classified Low, 87 Indeterminate and 14 High. Biopsy results indicated that two patients in the Low group and three in the Indeterminate group had significant fibrosis, while fibrosis was confirmed via biopsy in only four patients in the High group. Investigators calculated a sensitivity of 78%, specificity of 41%, positive predictive value (PPV) of 2% and negative predictive value (NPV) of 90% in the Low group. The High group had a reduced sensitivity of 44%, specificity of 94%, PPV of 29% and NPV of 97%.
“The NAFLD Fibrosis Score can’t accurately predict fibrosis for a bariatric patient population,” McKillop said. “We saw a significant number of patients who [tested] nonfibrotic who, on biopsy, were fibrotic, and vice versa. … There’s still an absolute need to do biopsy for accurate diagnosis for these patients.”
Disclosure: The researchers reported numerous financial disclosures.
For more information:
Simo KA. #1311: Calculated “NAFLD Fibrosis Scores” do not accurately predict degree of hepatic fibrosis in a bariatric patient population. Presented at: The Liver Meeting 2012; Nov. 9-13, Boston.