Controlled attenuation parameter: A measure of hepatic steatosis in patients with cystic fibrosis

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BackgroundHepatic steatosis is a common manifestation of CF-related liver disease(CFLD). Controlled attenuation parameter(CAP) measurement during transient elastography(TE) semiquantifies liver steatosis. We examined the relationship between CAP and CFLD severity, clinical factors and liver stiffness measurements(LSM). MethodsThis is a cross-sectional study of CF patients seen for outpatient care between January 2013–March 2014. CFLD severity was categorized as no CFLD, CFLD without portal hypertension(PHTN) and CFLD with PHTN, based on published criteria. Results129 patients (median 18.4y; 57% male) had valid CAP. 70(54%) had no CFLD, 44(34%) CFLD without PHTN, and 15(12%) CFLD with PHTN. The median CAP was 210 dB/m (IQR 181–239). Steatosis(CAP ≥230 dB/m) was seen in 27% of subjects without CFLD, 48% in CFLD but no PHTN, and 20% in with CFLD and PHTN(P = .04). CAP was higher for subjects with CFLD without PHTN (P < .05). There was no CAP difference between subjects with no CFLD and those with CFLD and PHTN (P ≥ .65). LSM was not different between no CFLD and CFLD without PHTN (P = .07), but each of these groups had lower LSM compared to subjects with CFLD and PHTN(P < .001 for each). Except for direct bilirubin, CAP was not associated with clinical markers of liver disease. ConclusionCAP was normal in 86(67%) of patients with CF and was not associated with standard clinical markers of liver disease. CAP was higher in patients with liver disease, which could possibly reflect the loss of steatosis observed with progression to cirrhosis and portal hypertension.