受控衰减参数诊断脂肪肝的临界值初探：一项多中心临床研究

A multi-center clinical study of a novel controlled attenuation parameter for assessment of fatty liver

目的 评价受控衰减参数（CAP）鉴别5％以上肝脂肪变的临界值及影响因素. 方法 纳入5个中心经“肝活体组织检查”证实的成年（＞18岁）非酒精性脂肪性肝病（NAFLD）及慢性乙型肝炎（CHB）患者332例,按病理学标准将肝脂肪含量分为S0（＜5％）、S1（≥5％）二个等级.使用FibroScan-502机型及M型探头完成CAP值测定.绘制CAP鉴别5％以上肝脂肪变的受试者工作特征曲线（ROC）及计算曲线下面积（AUROC）,采用最大Youden指数判定最佳临界值,并计算此值时的灵敏度及特异度等. 结果 332例患者中NAFLD组67例,年龄中位数及四分位间距（IQR）为39.0 （32.0 ～ 50.5）,CHB组同样年龄中位数及IQR为37.0 （28.0 ～ 45.0）,男性46例;CHB组共265例,年龄IQR为（28.0 ～ 45.0）岁,中位数为37.0岁,男性182例,两组间年龄、性别差异无统计学意义.多元线性回归分析提示,体质量指数（BMI）及肝脂肪变程度与CAP呈独立正相关.CAP在S0组IQR为（190.0 ～ 241.0） dB/m,中位数为215.0 dB/m,S1组IQR为（255.0 ～ 325.5） dB/m,中位数为294.0 dB/m,S1组显著高于S0组,P＜ 0.01.BMI＜25（kg/m2）时,CAP诊断5％脂肪变的AUROC为0.853,最佳临界值为244.5（dB/m）;BMI≥25（kg/m2）时,CAP诊断5％脂肪变的AUROC为0.835,最佳临界值为269.5 dB/m. 结论 CAP可以鉴别5％以上肝脂肪变,适用于脂肪肝的无创诊断,但需要对BMI进行校正.

Objective To evaluate the controlled attenuation parameter （CAP） assessment of fatty liver and choose a cut-off value of hepatic steatosis more than 5%.Methods Consecutive patients,18 years or older,who had undergone percutaneous liver biopsy and CAP measurement were recruited from five liver healthcare centers in China.All enrollees were categorized as hepatic steatosis grade S0 （〈5%） or S1 （≥5%）.An M-probe equipped FibroScan 502 was used to capture CAP values.Receiver operating characteristic （ROC） curves were plotted,and the areas under （AU） the curves were calculated to determine the diagnostic efficacy.The CAP cut-offvalues at the optimal thresholds were defined by maximum Youden indices; sensitivity and specificity were also calculated.Results A total of 332 patients were enrolled in the study,tcluding 67 patients with non-alcoholic fatty liver disease （NAFLD） and 265 with chronic hepatitis B （CHB） viru：infection.The median age （inter quartile range,IQR） of the study cohort was 39.0 （32.0-50.5） years-old.There were 46 males （68.7%） in the NAFLD group,with a median age of 37.0 （28.0-45.0） years-old,and 182 males （68.7%） in the CHB group; the differences between the two groups in median age and male：female ratio did not reach statistical significance.Multivariate linear regression analysis identified steatosis grade and body mass index （BMI） as independently associated with CAP.The median （IQR） CAP values among patients with S0 and S1 grade steatosis were 215.0 （190.0-241.0） dB/m and 294.0 （255.0-325.5） dB/m （P 〈 0.001）,respectively.For all patients,when BMIwas 〈25 kg/rn2,the ability of the AUROC of the CAP to discriminate hepatic steatosis ≥5% was 0.853,and the optimal cut-off value was 244.5 dB/m; however,when BMI ≥25 kg/m2,the AUROC was 0.835 and the optimal cut-off value 269.5 dB/m.Conclusion CAP can identify hepatic steatosis ≥5% and is applicable for the diagnosis of fatty liver if it is adjusted for BMI.