Determining the sensitivity and specificity of common diagnostic tests for carpal tunnel syndrome using latent class analysis

Abstract

Background: The accuracy of a diagnostic test used to classify a patient as having disease or being disease-free is a valuable piece of information to be used by the physician when making treatment decisions. If a standard reference test is available, determining the sensitivity and specificity of a new test is straightforward. However, if that reference test is incorrectly assumed to be perfectly sensitive and specific, the errors of the reference test can result in an underestimation of the accuracy of the test being evaluated. Latent class analysis can be applied to determine the sensitivity and specificity of a new test when no standard exists.

Methods: Latent class analysis was used to determine the accuracy rates of three commonly used measures of carpal tunnel syndrome: Tinel's sign, Phalen's test, and the nerve conduction velocity test. Data included 162 wrists from 81 patients seeking treatment for symptoms associated with carpal tunnel syndrome.

Results: Tinel's sign and Phalen's test were both highly sensitive (0.97 and 0.92, respectively) and specific (0.91 and 0.88, respectively). The sensitivity and specificity of the nerve conduction velocity test were 0.93 and 0.87, respectively.

Conclusion: Estimates of the sensitivity and specificity of these common tests for carpal tunnel syndrome support their widespread clinical use.