Development, External Validation, and Comparative... : Official journal of the American College of Gastroenterology | ACG (original) (raw)

ORIGINAL CONTRIBUTIONS

Development, External Validation, and Comparative Assessment of a New Diagnostic Score for Hepatic Steatosis

Meffert, Peter J PhD1; Baumeister, Sebastian E PhD1; Lerch, Markus M MD2; Mayerle, Julia MD2; Kratzer, Wolfgang MD3; Völzke, Henry MD1

1Institute for Community Medicine, Ernst Moritz Arndt University of Greifswald, Greifswald, Germany

2Department of Medicine A, Ernst Moritz Arndt University of Greifswald, Greifswald, Germany

3Department of Internal Medicine I, University of Ulm, Medical Centre, Ulm, Germany

Correspondence: Peter J. Meffert, Institute for Community Medicine, Ernst Moritz Arndt University of Greifswald, Walther-Rathenau-Str. 48, D-17475 Greifswald, Germany. E-mail: [email protected]

Received 20 December 2013; accepted 04 April 2014

Guarantor of the article: Peter J. Meffert, PhD.

Specific author contributions: Study concept and design, analysis and interpretation of data, drafting of the manuscript, and statistical analysis: Peter J. Meffert, Henry Völzke, and Sebastian E. Baumeister; critical revision of the manuscript for important intellectual content: Sebastian E. Baumeister, Julia Mayerle, Henry Völzke, Wolfgang Kratzer, and Markus M. Lerch; data collection: Wolfgang Kratzer, Henry Völzke; obtained funding, and study supervision: Henry Völzke.

Financial support: This work was supported by the German Federal Ministry of Education and Research (grants no. 01ZZ9603, 01ZZ0103, 01ZZ0403, and 03IS2061A); and the Ministry of Cultural, the Social Ministry of the Federal State of Mecklenburg-West Pomerania.

Potential competing interests: None.

Abstract

OBJECTIVES:

We used data from population-based studies to determine the accuracy of the Fatty Liver Index (FLI) and the Hepatic Steatosis Index (HSI) in determining individual risk of hepatic steatosis. We also developed a new risk scoring system and validated all three indices using external data.

METHODS:

We used data from the Study of Health in Pomerania (SHIP; n =4,222), conducted in North-eastern Germany, to validate the existing scoring systems and to develop our own index. Data from the South German Echinococcus Multilocularis and Internal Diseases in Leutkirch (EMIL) study ( n =2,177) were used as an external validation data set. Diagnostic performance was evaluated in terms of discrimination (area under the receiver operating characteristic curve (AUC)) and calibration plots. We applied boosting for generalized linear models to select relevant diagnostic separators.

RESULTS:

The FLI accurately discriminated patients with fatty liver disease from those without (AUC=0.817) but had poor calibration, in that predicted risks differed considerably from observed risks, based on SHIP data. The FLI performed well in discrimination and calibration in the analysis of EMIL data (AUC=0.890). The HSI performed worse than the FLI in analysis of both data sets (SHIP: AUC=0.782 and EMIL: AUC=0.841), showing an extremely skewed calibration. Our newly developed risk score had a good performance in the development data set (SHIP: AUC=0.860) and also good discrimination ability in the validation data (EMIL: AUC=0.876), but it had low calibration based on the validation data set.

CONCLUSIONS:

We compared the ability of the FLI, HSI, and our own scoring system to determine the risk of hepatic steatosis using two population-based data sets (one for the development of our own system and one for validation). In the development and independent replication data set, all three indices discriminated well between patients with and without hepatic steatosis, but the predicted risks did not match well with the observed risks, when applied to external data. Scoring systems for fatty liver disease could depend on methodological standardization of ultrasound diagnosis and laboratory measurements.