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Table 3 Modified elements of the QUADAS2 signalling questions used for quality assessment

From: Instrument-based tests for quantifying aqueous humour protein levels in uveitis: a systematic review protocol

Domain Patient selection Index test* Reference standard Flow and timing
Description Describe methods of patient selection: Describe included patients (prior testing, presentation, intended use of index test and setting): Describe the index test and how it was conducted and interpreted: Describe the reference standard and how it was conducted and interpreted: Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2x2 table (refer to flow diagram): Describe the time interval and any interventions between index test(s) and reference standard:
Signalling questions (yes/no/unclear) Was a consecutive or random sample of patients enrolled? Were the index test results interpreted without knowledge of the results of the reference standard? Is the reference standard likely to correctly classify the target condition? Was there an appropriate interval between index test(s) and reference standard?
Was a case-control design avoided? Were index test acquisition and analysis parameters determined a priori and consistent for all study participants? Were the reference standard results interpreted without knowledge of the results of the index test? Did all patients receive a reference standard?
Did the study avoid inappropriate exclusions?
i.e. Participants may be excluded if justified in terms of interference with index test measurement (corneal opacities preventing visualisation of anterior structures).
Did all patients receive the same reference standard?
i.e. Was the reference test conducted in the same way for each patient?
For slit lamp examination: observer, slit lamp settings
For laboratory protein measurements: method of aqueous extraction, sample storage and analysis.
Were all patients included in the analysis?
Risk of bias: High/low/unclear Could the selection of patients have introduced bias? Could the conduct or interpretation of the index test have introduced bias? Could the reference standard, its conduct, or its interpretation have introduced bias? Could the patient flow have introduced bias?
Concerns regarding applicability: High/low/unclear Are there concerns that the included patients do not match the review question? Are there concerns that the index test, its conduct, or interpretation differ from the review question? Are there concerns that the target condition as defined by the reference standard does not match the review question?  
  1. Italics denote signalling questions added by the authors for this systematic review.
  2. *In index test, the signalling question regarding whether thresholds were used and pre-specified is not applicable for this review and was therefore removed