Prevalence and Risk Factors of Focal Sparing in Hepatic Steatosis

Purpose: The prevalence, localization and potential risk factors for focal sparing were prospectively assessed in subjects with sonographically detectable hepatic steatosis as part of a population-based cross-sectional study. Materials and Methods: A total of 1,624 persons (n = 906 women; n = 718 men) were evaluated using ultrasonography, laboratory testing and a standardized questionnaire. The following were excluded from the analysis: subjects with reported alcohol consumption > 40 g/day (males) or > 20 g/day (females), those with known chronic hepatitis B or C infection, elevated serum transaminases (AST: m>44 U/l, f > 33 U/l; ALT: m>45 U/l, f > 35 U/l) and prior right nephrectomy. Results: The prevalence of focal sparing in patients with hepatic steatosis (grade I) was 25.6% for men and 13.0% for women. In patients with grade II/III disease, the prevalence was 70.9% for men and 77.6% for women. The most common site of focal sparing was in segment IV. The average diameter was 22.3mm (range 7-84 mm). No correlation was found for postulated risk age (p = 0.09) or status post cholecystectomy (p = 0.09). Male sex (p = 0.02) and metabolic syndrome (odds ratio, 2.1; 95% confidence interval, 1.1-4.1; p = 0.02) were confirmed as risk factors. Conclusion: Sonographic evidence of focal sparing in subjects with hepatic steatosis is associated with an increased risk for metabolic syndrome and may be an easily obtained diagnostic criterion in routine clinical settings.