The Minimal Clinically Important Difference of the Carpal Tunnel Syndrome Symptom Severity Scale

Purpose: To identify the change score in the Symptom Severity Scale (SSS) of the Carpal Tunnel Syndrome (CTS) Questionnaire that is associated with an important change in clinical status.

Methods: Twenty-eight patients with CTS were treated with a steroid injection to the carpal tunnel region. They completed the Brigham and Women's Hospital CTS Questionnaire before steroid injections and at the three-week follow-up visit. The minimal clinically important difference was calculated and receiver operating characteristic curves were created. The responsiveness of the entire SSS and the pain and sensory questions were compared in isolation.

Results: The SSS of the CTS Questionnaire, including its pain and sensory component, can show a meaningful clinical improvement after carpal tunnel injection. The SSS, its sensory domain, and its pain domain were of statistical significance. All three measures showed predictive ability; however, the total SSS was the most sensitive in detecting a change. The minimal clinically important difference in the score of the SSS after carpal tunnel steroid injection was found to be 1.04.

Conclusions: The SSS can be used to distinguish a clinically important change after carpal tunnel injection. A decrease of 1.04 or more in the SSS score may indicate a clinically important change in a patient's state of health.

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