| Background &Aims : Controlled attenuation parameter(CAP)is a noninvasive,quantitative,fast and reliable novel diagnostic tool for the assessment offatty liver diseases(FLD).It has been a hot research topic in the noninvasive strategies for the evaluation of FLD.The diagnostic value of CAP is certainly promising,but several other questions remain to be answered.The aim of this study were to study the influence of body position changes on the CAP values,and analyse the related factors of CAP values in general population,and compare CAP with other noinvasive menthods for diagnosis of FLD.Methods:(1)11 healthy volunteers were recruited from Xinhua hospital,and tested by Fibroscan when they were in their horizontal and sitting position.The results were analysed from two different body positions.(2)CAP and abdominal ultrasonography(US)were measured in a cohort subjects from the general population who underwent health physical examination in the Wujiaochang Community Health Service Center,and their indicators associated with Metabolic Syndrome(Met S)were collected.We analysed the related factors influencing CAP values and the diagnostic value of CAP for FLD and Met S.(3)The patients diagnosed with non-alcholic fatty liver disease(NAFLD)from liver clinic and the healthy participants from physical examination center of Xinhua hospital were recruited.Fibro Scan and abdominal US were performed for every participant.Their anthropometric and biochemical indicators were collected,fatty liver index(FLI)and liver accumulation product(LAP)were calculated,the diagnostic value of CAP for NAFLD were analysed and compared with related noinvasive methods.Rusults:(1)The 11 healthy volunteers consist of 4 men and 7 women with an age range from 24 to 39 years old.Match Wilcoxon signed rank test showed there was no significant differentce in the Fibroscan results between two different body positions(P>0.05).The intraclass correlation coefficient(ICC)of CAP and LSM were 0.492 and 0.772.Bland-Altman found that 90.9% of the difference values from different body positions distributed in the limits of agreement range.(2)The study population consist of 94 men and 42 women with an age range from 27 to 60 years old.42 cases were diagnosed with fatty liver by US,accounting for 30.9%;and 48 cases were diagnosed with Met S,accounting for 35.5%;There were no significant difference in age and gender between fatty liver group and the normal group;The CAP values range in the normal group was100-311 d B/m,the mean CAP values was 202±44d B/m,and the 95% reference range was117-276 d B/m;The CAP values range in the fatty liver group was 102-334 d B/m,the mean CAP values was 258±49d B/m,and 95% reference range was 180-328 d B/m;The alanine aminotransferase(ALT),triglycerides(TG),waist circumferase(WC),body mass index(BMI),systolic pressure,diastolic pressue,the radio of Met S and CAP values were significantly higher in the fatty liver group than in the normal group(all P <0.05),but high desity lipoprotein(HDL)in the fatty liver disease was significantly lower than that in the normal group;The statistical significance was not found in the fasting plasma glucose(FPG)and LSM between the two group(P>0.05);The CAP values in Met S group were also significantly higher than that in the non-Met S group(P < 0.0001);Spearman correlation analysis showed that CAP values were significantly associated with ALT,TG,WC,BMI and LSM;Multiple linear regression analysis showed that the BMI and LSM were independent associated with CAP.As the cut-off of 250 d B/m for the diagnosis with fatty liver,the Kappa value was 0.526 between diagnosis of fatty liver by CAP and by US(P<0.0001),the rate of agreement was 80.1%;ROC curve showed the optimal cut-off values for CAP predicting the fatty liver by US and Met S were 243 d B/m and236 d B/m,respectively.The area under the curve(AUC)were 0.810(95%CI:0.734-0.872) and 0.701(95%CI:0.617-0.777),respectively(all P<0.0001);(3)A total of 89 NAFLD patients and 94 healthy subjects were recruited.There were no significant difference in age and gender between the NAFLD group and the healthy group;The WC,BMI,gamma-glutamyl transpeptidase(GGT),ALT,TG,low-density lipoprotein(LDL),and LSM were significantly higher in the NAFLD group than those in the healthy group(all P<0.0001),but HDL in the NAFLD group was significantly lower than that in the normal group(P=0.0262);The CAP values,FLI and LAP of NAFLD group were significantly higher than those in the healthy group(all P < 0.0001);Spearman correlation analysis showed that CAP values were significantly associated with FLI(r=0.573,P<0.0001)and log(LAP)(r=0.480,P<0.0001)respectively.FLI was strongly significant associated with LAP(r=0.805,P<0.0001);ROC curve analysis demonstrated that CAP,FLI,LAP,BMI,WC,and TG showed moderate value for predicting NAFLD diagnosed by US,while CAP showed the highest AUC and Youden Index value of all,the AUC was0.871(95%CI:0.813-0.916),and the optimal cut-off of CAP predicting NAFLD was243 d B/m,the sensitivity and speciality rate were 74.2% and 87.2%,respectively.Conclusion:(1)The results of Fibro Scan is not influenced by the position,and Fibro Scan could be applied in the patients who can not be in their horizontal position.(2)The results of CAP were consistent with that of abdominal ultrasonography,CAP could be used not only to evaluate NAFLD,but also to assess Met S.(3)FLI and LAP show moderate diagnostic value,and CAP shows better diagnostic value than FLI and LAP. |
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