Critical appraisal:Thompson IM, Pauler DK, Goodman PJ, Tangen CM, Lucia MS, Parnes HL, et al 2004

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Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
PSA, DRE AUA
Condition that defined entry into study
At baseline PSA <3.0ng/mL, normal DRE and AUA <20
Setting
RCT - 221 centres
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Unclear
Did the study avoid inappropriate exclusions?
Yes
Reasons
no bias for diagnsotic performance in pre-screened cohort
Subgroup analysis for men with PSA less than or equal to 4.0 and normal DRE over 7 years
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
Focused on difficult to diagnose group normal DRE and PSA less than or equal to 4.0ng/mL
Index test 1
Describe index test and how it was conducted and interpreted
various PSA thresholds
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?
No
If two tests are being compared, have they been assessed independently / blind to each other?
Yes
What is the risk that the conduct or interpretation of the index test introduced bias?
Low
Comments
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
PSA > 4.0ng/mL
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
What is the risk that the conduct or interpretation of the index test introduced bias?
Low
Comments
Reference Standard
Describe the reference standard and how it was conducted and interpreted
84.5 % of men with PSA <4.0 underwent sextant biopsy
Is the reference standard likely to correctly classify the target condition?
No
Were the reference standard results interpreted without knowedge of the results of the index test/s?
Unclear
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?
High
Comments
Reference standard likely to miss some cancers
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
excluded men with PSA >4.0 so only a subgroup of TPs and FNs but the difference in TPs and the difference in FPs should be OK
Describe the time interval and any interventions between index test(s) and reference standard
> 1 year
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?
Yes
Did either all participants or a random sample of participants receive a reference standard test?
Yes
Did all patients receive the same reference standard irrespective of index test result?
Yes
Were all test results including unclear results reported?
Unclear
Were all patients included in the analysis?
No
What is the risk that the patient flow introduced bias?
Low
Comments
in another publication of this trial missing data imputed and results were similar therefore absence of some participants from analysis unlikely to cause bias 
subgroup of men with PSA <4.0 inlcuded low risk of bias for difference in TPs and FPs
Overall risk of bias
At risk of bias Additional comments: reference standard likely to miss some cancers


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Article
Thompson IM, Pauler DK, Goodman PJ, Tangen CM, Lucia MS, Parnes HL, et al. Prevalence of prostate cancer among men with a prostate-specific antigen level < or =4.0 ng per milliliter. N Engl J Med 2004 May 27;350(22):2239-46 Available from: http://www.ncbi.nlm.nih.gov/pubmed/15163773.
Assigned to
User:Suzanne.hughes
Topic area
Guidelines:PSA Testing/PSA Protocols
Clinical question
Form
Form:Quality appraisal quadas


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