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Table 3 Assessment of comparative studies using the QUADAS tool

From: Methods for identifying surgical wound infection after discharge from hospital: a systematic review

QUADAS Item Sands (1996) Sands (1999) Sands (2003) Whitby (2002) Seaman & Lammers (1991) Mitchell (1999) Martini (2000)
Was the spectrum of patients representative of the patient who will receive the test in practice? Yes Yes No. CABG patients with a probability score of 0.1 of developing an SSI. No. Chose moderate to high-risk patients only. No. Only included patients with lacerations treated at A & E. Yes Unclear. Not enough information presented
Were the selection criteria clearly described? Yes Yes Yes No. Patients included if had a surgical wound that could be easily observed and if procedure undertaken had a moderate to high risk infection probability but not stated how this was calculated. Yes No. No
Is the reference standard likely to correctly classify the target condition. Unclear Unclear No. Relies on reporting, no observation. Unclear. Different health professionals engaged in study had different levels of agreement. Yes Unclear No.
Is the time period between the reference standard and index test short enough to be reasonably sure that the target condition did not change between the two tests?     Unclear. As authors did not specify what type of surgery was undertaken it is not known whether the follow-up period was sufficient to detect infections. Unclear No Unclear
Did the whole sample or a random selection of the sample, receive verification using a reference standard of diagnosis? Yes Yes Yes Yes Yes No. Only those whose surgeon completed the questionnaire Yes
Did patients receive the same reference standard regardless of the test result? Yes Yes Yes Yes Yes Yes Yes
Was the reference standard independent of the index test (i.e. the index test did not form part of the reference standard)? Unclear Yes No Yes Yes Yes Yes
Was the execution of the index test described in sufficient detail to permit replication of the test? Unclear Unclear Yes Yes Yes Unclear Yes
Was the execution of the reference test described in sufficient detail to permit replication of the test? Yes Yes No Yes Yes Yes Yes
Were the index test results interpreted without knowledge of the results of the reference test? Unclear Unclear Unclear Yes Yes Unclear Yes
Were the results of the reference standard interpreted without knowledge of the results of the index test? Unclear Unclear Unclear Yes No Unclear Yes
Were the same clinical data available when test results were interpreted as would be available when the test is used in practice? No. The information available in this standard would not be available in the UK. No. The information available in this standard would not be available in the UK. No. The information available in this standard would not be available in the UK. Yes Yes Yes Yes
Were uninterpretable/Intermediate test results reported? Unclear Unclear Unclear Unclear Unclear Unclear Unclear
Were withdrawals from the study explained? Unclear Unclear Unclear Unclear Yes Unclear Unclear