Accuracy of ultrasound to identify chronic liver disease

Table 2 Quality assessment of diagnostic accuracy studies assessment items

Item	Question	Guidelines for assessment	Aspect of study assessed
1	Was the spectrum of patients representative of the patients who will receive the test in practice?	Patients who receive the test in clinical practice will be suspected of having chronic liver disease but not yet have decompensated cirrhosis	Generalisability
		Sample populations should fit this general characteristic. Samples may be a mixed population or may be restricted to one disease type if this is a common and clinically important disease, in this case alcohol abusers or viral hepatitis
		Score “yes” if clearly stated and meet the above definitions, “no” if the spectrum is clearly outside this definition and “unclear” if there is insufficient information
2	Were selection criteria clearly described?	Clear definitions of the inclusion and exclusion criteria should be included. “Yes” if clearly stated, “no” if not stated and ‘unclear” if only partially stated	Quality of reporting
3	Is the reference standard likely to correctly classify the target condition?	Liver biopsy must be used as the reference standard. “Yes” if biopsy used, “no” if not and “unclear’ if not stated	Presence of bias
4	Is the time period between reference standard and index test short enough to be reasonably sure that the target condition did not change between the two tests?	The time period must be no more than one month for all cases to avoid discrepancies between the index and reference test due to disease progression. The order in which the tests are done is not relevant. Score “yes” if one month or less, “no” if more than one month and “unclear” if not clearly stated	Presence of bias
5	Did the whole sample or a random selection of the sample, receive verification using a reference standard?	All patients should receive a biopsy unless some form of randomisation was used. Score “no” if some patients were excluded. Score “unclear” if this information is not reported by the study	Presence of bias
6	Did patients receive the same reference standard regardless of the index test result?	If it is clear all patients received a liver biopsy, score “yes”. If some received laparoscopy (or other test), score “no”. If it is not stated, score “unclear”	Presence of bias
7	Was the reference standard independent of the index test (i.e. the index test did not form part of the reference standard)?	Score ‘yes” if the index test did not form part of the reference test, “no” if it did and “unclear” if not stated or there is doubt	Presence of bias
8	Was the execution of the index test described in sufficient detail to permit replication of the test?	Studies should describe equipment and techniques in sufficient detail to enable replication. Ultrasound criteria for identifying fibrosis or cirrhosis must be clearly stated and be able to be replicated (e.g. clear and easily reproducible system for assessing grey scale appearances or Doppler measurements or indices)	Quality of reporting
		Score “yes” if the above is true, “no” if these details are not stated or if the technique described is not able to be replicated and “unclear” if an incomplete description is given
9	Was the execution of the reference standard described in sufficient detail to permit its replication?	A clear description of the biopsy technique sufficient to enable replication. Ideally this should include information about the needle technique used and the minimum size of the sample. A recognised staging system for fibrosis or a description with sufficient detail to enable replication must be provided	Quality of reporting
		Score “yes” if the above are true, “no” if no description of technique is given OR no staging system used and “unclear” if a partial description is given from which conclusions cannot be reached
10	Were the index test results interpreted without knowledge of the results of the index test?	Score “yes” if the ultrasound was performed and reported without knowledge of the biopsy. Score “no” if this is not the case and “unclear” if it is not stated	Presence of bias
11	Were the reference standard results interpreted without knowledge of the results of the reference test?	Score “yes” if the biopsy was performed and reported without knowledge of the ultrasound. Score “no” if this is not the case and “unclear” if it is not stated	Presence of bias
12	Were the same clinical data available when test results were interpreted as would be available when the test is used in practice?	Score “yes’ if pre-test clinical data was available for the ultrasound and biopsy. Score “no” if it was not available. Score “unclear” if it is not stated	Presence of bias
13	Were uninterpretable/intermediate results reported?	Score “yes” if all test results, including uninterpretable or indeterminate results, are accounted for. Score “no” if some data is missing and not explained or has been excluded from analysis. Score “unclear” if it is not clear whether all results have been included	Quality of reporting
14	Were withdrawals from the study explained?	A flow chart or matching numbers in a 2 × 2 table can help assess this item	Quality of reporting
		If it is clear what happened to all participants, score “yes”. If some patients are not accounted for, score “no”. Score “unclear” if interpretation is difficult