Abstract
Objectives
To determine whether the diagnostic accuracy of the liver fibrosis marker FIB-4 and the likelihood ratios (LRs) of specific FIB-4 values vary with age.
Methods
We used a published dataset of 540 patients diagnosed with non-alcoholic fatty liver disease (NAFLD) or non-alcoholic steatohepatitis. Liver biopsy showed no or early fibrosis in 391 patients, and advanced fibrosis in 149. For each group we established the relation between the mean of the natural logarithm of FIB-4 (log(FIB-4)) and age, and the standard deviation (SD) of log(FIB-4) and age. Using a parametric method, we calculated the area under the ROC curve of FIB-4 as a function of the difference in mean values of log(FIB-4) between the two groups, and the ratio of the SDs of log(FIB-4). LRs were calculated as functions of age at 35, 50 and 65 years, using a parametric method.
Results
The mean log(FIB-4) increased with age in both groups. The SDs of log(FIB-4) did not change with age. There was a trend towards decreasing diagnostic accuracy with age, but this finding did not reach statistical significance. The area under the ROC curve was 0.73 using a parametric method that accounted for age, and 0.79 using a traditional non-parametric method that did not account for age. The LRs of specific FIB-4 values decreased with age.
Conclusions
Age distorts the estimation of both diagnostic accuracy and LRs.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The authors state no conflict of interest.
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Research funding: None declared.
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Data availability: Not applicable.
References
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