Section 1: Study Validity

Evaluation criterion	How well was this criterion addressed?
What were the key selection (inclusion & exclusion) criteria? Were they well defined? Were they replicable?	180 consecutive patients referred for electrodiagnostic evaluation for suspected CTS with at least 1 symptom indicative of possible CTS (numbness /tingling /nocturnal aggravation / pain that can be “shaken out”/ pain after frequent wrist or hand use / dropping items / difficulty holding items / hand pain). Exclusions: generalized peripheral neuropathy, previous CTS surgery, cervical radiculopathy, other neuromuscular disorders. There were bilateral symptoms in 85, thus a total of 225 hands in the study.
Were selection criteria appropriate given study question?	The study did not specifically examine a diabetic population although there were diabetic patients in the study (number not specified in paper). A higher prevalence of CTS would be anticipated in this population (patients referred for testing re ?CTS) and the severity of disease would be higher than in the population of Type 2 diabetics with ?CTS that our patient comes from.
Did selection lead to an appropriate spectrum of participants (like those assessed in practice)	Yes but the number of diabetics is not stated and the study uses a pre-selected population as discussed above.
What was the reference standard of diagnosis? Was it clearly defined, independent & valid?	Nerve conduction studies (NCS) were used as the gold standard. The details of the testing and the electrodiagnostic criteria needed for CTS diagnosis were clearly described.
Was the reference standard applied regardless of test result?	Yes, all patients in the study underwent NCS.
Was the reference standard assessed blind to test result?	No. Reference testing was performed after the Tinel (and other) signs were tested and recorded. It appears that the same investigator performed both the Tinel’s test and the NCS. The order in which the 6 different signs were performed is not stated and there was no blinding, meaning that the results of one test could well affect another. However objective criteria (as above) were used for the classification of the NCS results.
What tests were used? Were they well defined? Replicable?	6 different CTS signs were used: Phalen sign, Hoffman-Tinel sign, hypesthesia, abductor pollicis brevis (APB) weakness, median nerve compression and square-shaped wrist. The tests are clearly described, including photographs of the less well-known signs.
Was the test applied regardless of the reference standard result?	Yes.
Was test assessment blind to reference standard result?	Yes, eliciting of signs occurred prior to NCS testing.
Was the test validated in a second, independent group?	No.