Validation of the Williams ultrasound scoring system for the diagnosis of liver disease in cystic fibrosis

Abstract

To describe the hepatic abnormalities revealed by ultrasound examination of cystic fibrosis (CF) patients followed at the CF Outpatient Clinic at the Federal University of Minas Gerais; to compare ultrasound data with clinical and biochemical parameters; to validate the Williams ultrasound score for the diagnosis of liver disease in CF. Seventy cystic fibrosis patients were followed prospectively and underwent clinical, biochemical and ultrasound examinations. The ultrasound findings were compared to the results of the clinical and biochemical examinations. Clinical and biochemical criteria were used as the gold standard for the validation of the Williams ultrasound score. We calculated the sensitivity, specificity, and positive and negative predictive values for the Williams score. The patients were divided into two groups: normal (score = 3) or abnormal (score > 3) ultrasound examination. Ten patients met the clinical and/or biochemical criteria for liver disease (14.3%). All of them presented some abnormality on ultrasound examination of the liver. Abnormalities of the hepatic parenchyma, edge and periportal fibrosis were statistically more frequent in these patients. The Williams ultrasound score showed high specificity (91.7%; CI 80.9-96.9), but low sensitivity (50%; CI 20.1-79.9) for the diagnosis of liver disease. The Williams ultrasound score was not a good screening tool when compared to the clinical and biochemical examinations. Since there are currently no adequate tests that can be used to diagnose liver disease, we recommend a sequential evaluation combining clinical, biochemical and ultrasound examinations for the diagnosis of liver disease in CF.