Original Article
Copyright ©2010 Baishideng. All rights reserved.
World J Gastroenterol. Jul 28, 2010; 16(28): 3510-3520
Published online Jul 28, 2010. doi: 10.3748/wjg.v16.i28.3510
Accuracy of ultrasound to identify chronic liver disease
Richard Allan, Kerry Thoirs, Maureen Phillips
Richard Allan, Division of Medical Imaging, Flinders Medical Centre, Flinders Drive, Bedford Pk, 5042, South Australia, Australia
Richard Allan, Maureen Phillips, School of Health Sciences, University of South Australia, City East Campus, North Terrace, Adelaide, 5000, South Australia, Australia
Kerry Thoirs, International Centre of Allied Health Evidence, University of South Australia, City East Campus, North Terrace, Adelaide, 5000, South Australia, Australia
Author contributions: Allan R provided the largest contribution; designing and performed the research, analysing and interpreting the data and writing the paper; Thoirs K and Phillips M made a substantial contribution by reviewing procedures, drafts, analysis and providing advice on the design and analysis phases of the project; Allan R and Thoirs K performed the methodological assessment of the included journal articles.
Supported by The Division of Medical Imaging at Flinders Medical Centre, Flinders Drive, Bedford Pk, 5042, South Australia, Australia
Correspondence to: Dr. Kerry Thoirs, International Centre of Allied Health Evidence, University of South Australia, City East Campus, North Terrace, Adelaide, 5000, South Australia, Australia. kerry.thoirs@unisa.edu.au
Telephone: +61-8-83022903 Fax: +61-8-83021818
Received: March 24, 2010
Revised: April 21, 2010
Accepted: April 28, 2010
Published online: July 28, 2010
Abstract

AIM: To identify and assess studies reporting the diagnostic performance of ultrasound imaging for identifying chronic liver disease (CLD) in a high risk population.

METHODS: A search was performed to identify studies investigating the diagnostic accuracy of ultrasound imaging for CLD. Two authors independently used the quality assessment of diagnostic accuracy studies (QUADAS) checklist to assess the methodological quality of the selected studies. Inter-observer reliability of the QUADAS tool was assessed by measuring the degree of agreement (percent agreement, κ statistic) between the reviewers for each assessment prior to a consensus meeting. The characteristics of each study population, sensitivity and specificity results for the index tests, and results of any testing for observer agreement were extracted from the reports. Receiver Operator Characteristic plots were generated using Microsoft Excel 2003 software and used to graphically display the diagnostic performance data and to explore the relationships between the reported ultrasound techniques and study characteristics, and methodology quality.

RESULTS: Twenty-one studies published between 1991 and 2009 were retained for data extraction, analysis and assessment for methodological quality. Assessment of methodology quality was performed on the 21 selected studies by two independent reviewers (RA & KT) using the QUADAS assessment tool. Across all studies the mean number of responses within the QUADAS assessment tool was 10 (range 7-13) for “Yes”, 1 (range 0-3) for “No” and 3 (range 0-6) for “unclear”. Inter-rater agreement for assessment of methodology quality was significantly greater than chance when assessing for representative spectrum, clear selection criteria, appropriate delay between reference and index tests, adequate descriptions of the index and reference tests, reference and index test blinding, and if relevant clinical information was provided. Seven studies reported moderate to high observer agreement for ultrasound techniques. Studies which clearly reported blinding performed better than the other studies for diagnostic accuracy, and lower diagnostic accuracy was evident for populations with lower prevalence of disease. Assessment of the liver surface using ultrasound consistently had moderate diagnostic accuracy across studies which demonstrated good research methodology. Other techniques demonstrated variable or poor to fair diagnostic accuracy.

CONCLUSION: Ultrasound of the liver surface is a useful diagnostic tool in patients at risk of CLD when assessing whether they should undergo a liver biopsy.

Keywords: Chronic liver disease; Liver surface; Systematic review; Ultrasonography