2. QUADAS‐2 tool.
| Item | Response (delete as required) |
| Participant selection – Risk of bias | |
| 1) Was a consecutive or random sample of participants or teeth used? |
Yes – where teeth or participants were selected consecutively or allocated to the study via a randomisation process No – if study described another method of sampling Unclear – if participant sampling is not described |
| 2) Was a case‐control design avoided? |
Yes – if case‐control clearly not used No – if study described as case‐control or describes sampling specific numbers of participants with particular diagnoses Unclear – if not clearly described |
| 3) Did the study avoid inappropriate exclusions (e.g. inclusion of caries into dentine)? |
Yes – if the study clearly reports that included participants or teeth were apparently healthy or caries into dentine were excluded No – if lesions were included that showed caries into dentine or exclusions that might affect test accuracy (e.g. teeth with no caries) Unclear – if not clearly reported |
| Could the selection of participants have introduced bias? | |
| If answers to all of questions 1) and 2) and 3) was 'yes' | Risk is low |
| If answers to any of questions 1) and 2) and 3) was 'no' | Risk is high |
| If answers to any of questions 1) and 2) and 3) was 'unclear' | Risk is unclear |
| Participant selection – Concerns regarding applicability | |
| 1) Does the study report results for participants or teeth selected by apparent health or suspected early caries (i.e. studies do not recruit patients who are known to have advanced caries into dentine)? |
Yes – if a group of participants or teeth has been included which is apparently healthy or indicative of early caries No – if a group of participants or teeth has been included which is suspected of advanced caries Unclear – if insufficient details are provided to determine the spectrum of participants or teeth |
| 2) Did the study report data on a per‐patient rather than on a tooth or surface basis? |
Yes – if the analysis was reported on a surface or tooth basis No – if the analysis was reported on a per‐patient basis Unclear ‐ if it is not possible to assess whether data are presented on a per‐patient or per‐tooth basis |
| 3) Did the study avoid an in vitro setting which required the usage of extracted teeth? |
Yes – if the participants were recruited prior to tooth extraction No – if previously extracted teeth were used in the analysis Unclear – if it was not possible to assess the source and method of recruiting of included participants/teeth |
| Is there concern that the included participants or teeth do not match the review question? | |
| If answers to all of questions 1) and 2) and 3) was 'yes' | Risk is low |
| If answers to any of questions 1) and 2) and 3) was 'no' | Risk is high |
| If answers to any of questions 1) and 2) and 3) was 'unclear' | Risk is unclear |
| Index test ‐ Risk of bias (to be completed per test evaluated) | |
| 1) Was the index test result interpreted without knowledge of the results of the reference standard? |
Yes – if the index test described is always conducted and interpreted prior to the reference standard result, or for retrospective studies interpreted without prior knowledge of the reference standard No – if index test described as interpreted in knowledge of reference standard result Unclear – if index test blinding is not described |
| 2) Was the diagnostic threshold at which the test was considered positive pre‐specified? |
Yes – if threshold was pre‐specified (i.e. prior to analysing the study results) No – if threshold was not pre‐specified Unclear – if not possible to tell whether or not diagnostic threshold was pre‐specified |
| For visual and radiograph tests only: 3) For studies reporting the accuracy of multiple diagnostic thresholds for the same index test or multiple index tests, was each threshold or index test interpreted without knowledge of the results of the others? |
Yes – if thresholds or index tests were selected prospectively and each was interpreted by a different clinician or interpreter, or if study implements a retrospective (or no) cut‐off (i.e. look for deepest/most severe lesion first) No – if study states reported by same reader Unclear ‐ if no mention of number of readers for each threshold or if pre‐specification of threshold not reported N/A ‐ multiple diagnostic thresholds not reported for the same index test |
| Could the conduct or interpretation of the index test have introduced bias? | |
| For visual and radiographic studies item 3) to be added | |
| If answers to all of questions 1) and 2) was 'yes' | Risk is low |
| If answers to any of questions 1) and 2) was 'no' | Risk is high |
| If answers to any of questions 1) and 2) was 'unclear' | Risk is unclear |
| Index test ‐ Concerns regarding applicability | |
| 1) Were thresholds or criteria for diagnosis reported in sufficient detail to allow replication? |
Yes – if the criteria for detection or diagnosis of the target disorder were reported in sufficient detail to allow replication No – if the criteria for detection or diagnosis of the target disorder were not reported in sufficient detail to allow replication Unclear ‐ if some but not sufficient information on criteria for diagnosis to allow replication were provided |
| 2) Was the test interpretation carried out by an experienced examiner? |
Yes – if the test clearly reported that the test was interpreted by an experienced examiner No – if the test was not interpreted by an experienced examiner Unclear – if the experience of the examiner(s) was not reported in sufficient detail to judge or if examiners described as 'Expert' with no further detail given |
| Is there concern that the included participants do not match the review question? | |
| If the answer to question 1) and 2) was 'yes' | Concern is low |
| If the answer to question 1) and 2) was 'no' | Concern is high |
| If the answer to question 1) and 2) was 'unclear' | Concern is unclear |
| Reference standard ‐ Risk of bias | |
| 1) Is the reference standard likely to correctly classify the target condition? |
Yes – if all teeth or surfaces underwent a histological or excavation reference standard No – if a final diagnosis for any participant or tooth was reached without the histological or excavation reference standards Unclear – if the method of final diagnosis was not reported |
| 2) Were the reference standard results interpreted without knowledge of the results of the index test? |
Yes – if the reference standard examiner was described as blinded to the index test result No – if the reference standard examiner was described as having knowledge of the index test result Unclear – if blinded reference standard interpretation was not clearly reported |
| Could the reference standard, its conduct, or its interpretation have introduced bias? | |
| If answers to questions 1) and 2) was 'yes' | Risk is low |
| If the answer to question 1) and 2) was 'no' | Concern is high |
| If the answer to question 1) and 2) was 'unclear' | Concern is unclear |
| Reference standard ‐ Concerns regarding applicability | |
| 1) Does the study use the same definition of disease positive as the prescribed in the review question? |
Yes ‐ same definition of disease positive used, or teeth can be disaggregated and regrouped according to review definition No ‐ some teeth cannot be disaggregated Unclear ‐ definition of disease positive not clearly reported |
| Flow and timing ‐ Risk of bias | |
| 1) Was there an appropriate interval between index test and reference standard (in vivo studies less than 3 months, in vitro no limit but must be stored appropriately)? |
Yes ‐ if study reports index and reference standard had a suitable interval or storage method No ‐ if study reports greater than 3‐month interval between index and reference standard or inappropriate storage of extracted teeth prior to reference standard Unclear ‐ if study does not report interval or storage methods between index and histological reference standard |
| 2) Did all participants receive the same reference standard? |
Yes ‐ if all participants underwent the same reference standard No ‐ if more than 1 reference standard was used Unclear ‐ if not clearly reported |
| 3) Were all participants included in the analysis? |
Yes ‐ if all participants were included in the analysis No ‐ if some participants were excluded from the analysis Unclear ‐ if not clearly reported |
| If answers to questions 1) and 2) and 3) was 'yes' | Risk is low |
| If answers to any one of questions 1) or 2) or 3) was 'no' | Risk is high |
| If answers to any one of questions 1) or 2) or 3) was 'unclear' | Risk is unclear |
N/A = not applicable; QUADAS‐2 = Quality Assessment of Diagnostic Accuracy Studies 2.