Abstract
The reliability of the scratch-collapse test for diagnosis of carpal tunnel syndrome
(CTS) has not been tested by independent investigators. This study measured the reliability
of the scratch-collapse test comparing the treating hand surgeon and blinded evaluators.
We performed a prospective observational study of 41 patients with a provisional diagnosis
of CTS or a combination of CTS and cubital tunnel syndrome and prescribed electrodiagnostic
testing. The treating hand surgeon performed the scratch-collapse test. Next, the
test was administered by one of the six observers, unaware of the patient’s symptoms
and the diagnosis made by treating hand surgeon. The kappa statistic (κ) was used
to calculate the interrater reliability between the treating hand surgeons and blinded
scratchers. The agreement between the blinded observers and the hand surgeons on the
scratch-collapse test was substantial 0.63 (95 % CI, 0.34 0.87; p <0.001). The sensitivity of the blinded scratch test in our sample was 32 %. In a small study with a spectrum bias favoring electrophysiologically confirmed
CTS the reliability was lower than that reported by the inventors of the test, but
was still substantial. We propose a larger study of patients with a greater variety
of electrodiagnostic test results using fewer observers with more experience.
Keywords
Scratch-collapse test - Interobserver reliability - Carpal tunnel syndrome
