Critical appraisal:Wagner T, Chevreau C, Meyer N, Mourey L, Courbon F, Zerdoud S 2012 2

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Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
NA
Condition that defined entry into study
All 48 patients had pathologically proven cutaneous melanoma, presented with an ulcerated melanoma with a Breslow thickness of >1mm or ≥4mm, and were eligible for SLNB procedure.
Setting
Patients underwent FDG PET-CT for initial staging at the Claudius Regard comprehensive cancer care center, Toulouse, France, between September 2003 and September 2006.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Yes
Did the study avoid inappropriate exclusions?
Yes
Reasons
Patients had no clinical or paraclinical signs of nodal involvement or distant metastases at the time they were referred.
If comparing more than one index test was the design fully paired or paired randomly?
Not applicable
If a paired randomised design was used, was allocation to groups concealed and was the generation of allocation sequence adequate?
Not applicable
What is the risk that the selection of participants introduced bias?
Low
Comments
Index test 1
Describe index test and how it was conducted and interpreted
Whole-body FDG PET/CT imaging.

Images were interpreted by at least one experienced nuclear medicine specialist who was aware of all the clinical findings.

Were the index test results interpreted without knowledge of the results of the reference standard?
Yes
If a threshold was used, was it pre-specified?
Yes
If two tests are being compared, have they been assessed independently / blind to each other?
Not applicable
What is the risk that the conduct or interpretation of the index test introduced bias?
High
Comments
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
NA
Were the index test results interpreted without knowledge of the results of the reference standard?
Not applicable
If a threshold was used, was it pre-specified?
Not applicable
What is the risk that the conduct or interpretation of the index test introduced bias?
Not applicable
Comments
Reference Standard
Describe the reference standard and how it was conducted and interpreted
Nodal status was confirmed by pathological examination (SLNB or therapeutic lymph node dissection - TLND).


Metastasis was confirmed on the data of conventional imaging and clinical follow-up (6 months), and/or by histological examination of a biopsy of the lesion whenever feasible.

Initial PET evaluations were considered as true negative, true positive, false negative or false positive depending on the presence or absence of detectable metastatic disease within 6 months after the PET scan.

Is the reference standard likely to correctly classify the target condition?
Yes
Were the reference standard results interpreted without knowedge of the results of the index test/s?
No
Was the reference test standard independent of the index test?
(i.e. the index test did not form part of the reference standard)
Yes
What is the risk that the reference standard, its conduct or interpretation introduced bias?
Unclear
Comments
Flow and timing
Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2x2 table
FDG PET-CT identified regional nodal metastases in six patients, of which 2 were confirmed by therapeutic lymph node dissection (and did not undergo CT scan or ultrasound imaging or SLNB).

Four of these patients had SLNB, where 3 were confirmed for metastatic nodal deposits and one underwent surgical dissection for pathological confirmation of the hot node harbouring metastatic deposits.

SLNB was performed in 41 patients.

Describe the time interval and any interventions between index test(s) and reference standard
None specified.
If a predictive test (the reference standard is a later event that the test aims to predict) were any subsequent interventions between test and later event blind to test result?
Not applicable
Was there an appropriate interval between index test(s) and reference standard?
Unclear
Did either all participants or a random sample of participants receive a reference standard test?
No
Did all patients receive the same reference standard irrespective of index test result?
No
Were all test results including unclear results reported?
Yes
Were all patients included in the analysis?
Yes
What is the risk that the patient flow introduced bias?
Low
Comments
Not all patients received the same reference standard test. For regional node status only 5 patients did not undergo SLNB or TLND and therefore were not confirmed by a reference test. For distant metastasis detection only 42/48 patients received follow-up to confirm PET-CT results.
Overall risk of bias
At risk of bias Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating


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Article
Wagner T, Chevreau C, Meyer N, Mourey L, Courbon F, Zerdoud S. Routine FDG PET-CT in patients with a high-risk localized melanoma has a high predictive positive value for nodal disease and high negative predictive value for the presence of distant metastases. J Eur Acad Dermatol Venereol 2012 Nov;26(11):1431-5 Available from: http://www.ncbi.nlm.nih.gov/pubmed/22017492.
Assigned to
User:Tamsin.parrish
Topic area
Guidelines:Melanoma
Clinical question
Form
Form:Quality appraisal quadas


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