Statistical analysis
Categorical variables are shown as percentages and continuous variables as medians with interquartile range (25th and 75th percentiles) due to the distribution. Distribution relationship between categorical variables values was tested using χ2-test, and if necessary, Fisher’s exact test. To analyze the difference between three continuous variables Kruskal-Wallis test with post hoc Mann-Whitney U-test for non-parametric analysis was used, while the difference between two continuous variables was tested using Mann-Whitney U-test. Multivariable logistical regression analyses were conducted to identify patient characteristics independently associated with coffee consumption, sleeping and smoking. Those factors with a p value <0.05 in the univariate analyses were selected as candidate variables for backward multivariable logistical regressions. Finally, focused analysis of coffee consumption, sleeping and smoking association with CAP and LSM was performed in unadjusted and three adjusted models (Model 1, 2 and 3) to determine the consistency or change of influence among variables. All the statistical analyses were performed using SPSS V.22.0 (SPSS Inc, Chicago, Illinois, USA). Statistical tests were two-tailed and significance was set at 0.05.