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

Critical Appraisal

Article being appraised

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.

Applicable clinical question

What investigations should be performed following a diagnosis of primary cutaneous melanoma for asymptomatic stage I and stage II patients?

Key Facts

Study Design

diagnostic accuracy study

Study aims:

To assess the role of routine staging with FDG PET-CT in melanoma patients with localised high risk melanoma.

Number of Patients:

48

8 stage IIA, 19 stage IIB and 19 IIC patients. The ulceration status of two patients was not available but BT was >4mm therefore they were either stage IIB or IIC.

Reported outcome(s):

Sensitivity
Specificity
Positive predictive value (PPV)
Negative predictive value (NPV)

Results of outcome(s):

For regional nodal assessment sensitivity, specificity, positive predictive value and negative predictive value of PET were 43%, 100%, 100% and 78%, respectively. The above outcomes were not specified for SLNB.

Includes an economic evaluation

no

Evidence ratings

Level of evidence

III-2

Risk of bias

At risk of bias

Comments: Please replace this text and include any additional comments in regards to your risk of bias rating

Show/Hide Risk of bias assessment

Risk of bias assessment: diagnostic accuracy study

Patient Selection

Prior tests and any referral filters

pathology to prove cutaneous melanoma

Condition that defined entry into study

All patients presented with either an ulcerated melanoma with a BT > 1mm or with either an ulcerated melanoma with a BT ≥ 4mm, but did not present with any clinical or paraclinical signs of nodal involvement or distant metastases at the time they were referred.

Setting

Claudius Regaud comprehensive cancer care center (CCR, 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

No response

If comparing more than one index test was the design fully paired or paired randomly?

Yes

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

No response

Index test 1

Describe index test and how it was conducted and interpreted

FDG-PET

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?

No

What is the risk that the conduct or interpretation of the index test introduced bias?

High

Comments

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

Index test 2

Describe index test and how it was conducted and interpreted, if applicable

N/A

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

No response

Reference Standard

Describe the reference standard and how it was conducted and interpreted

Pathological examination.

The diagnosis of metastasis was considered as confirmed on the data of conventional imaging and clinical follow up, and/or histological examination.

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

No response

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

Only 41 or the 48 patients underwent SLNB procedure. In one patient SLN could not be detected, and for 7 patients, the SLNB procedure was not performed (for technical reasons for five patients and positive FDG PET-CT for regional node in two patients).

Describe the time interval and any interventions between index test(s) and reference standard

Not 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?