The six-item CTS symptoms scale and palmar pain scale in carpal tunnel syndrome

Abstract

Purpose: To evaluate measurement properties of 2 brief outcome measures for carpal tunnel syndrome: the 6-item carpal tunnel symptoms scale (CTS-6) and the 2-item palmar pain scale (measuring severity of pain in the scar/palm and pain-related activity limitation). Our hypothesis was that the CTS-6 is responsive to change in symptoms after surgical treatment and the pain scale is a valid measure of surgery-related pain.

Methods: This study followed 447 consecutive patients with carpal tunnel syndrome undergoing open release; 308 completed the CTS-6 and the Disabilities of the Arm, Shoulder, and Hand-short form (QuickDASH) before surgery and the CTS-6, QuickDASH, palmar pain scale, and 2 items regarding global rating of change and treatment satisfaction once after surgery (range, 2-13 mo). The mean scores for the CTS-6 (range, 1-5) and QuickDASH and palmar pain scales (range, 0-100) were calculated (lower score is better). Responsiveness was assessed with the effect size (ES). We estimated the CTS-6 score change indicating minimal clinically important difference based on scores for patients with moderate self-rated improvement.

Results: The mean baseline CTS-6 score was 3.16, mean change after surgery was -1.54 (95% confidence interval [CI], -1.65 to -1.44), and ES was 2.0. The ES was large (2.5) in patients with the largest self-rated improvement and decreased with lower self-rated improvement. A score change of 0.9 indicated a minimal clinically important difference. The mean change in QuickDASH score was -25.4 (95% CI, -27.8 to -23.0), and ES was 1.25. The mean palmar pain score for patients with time since surgery of less than 3 months was 38.5, at 3 to 6 months was 35.4, and greater than 6 months was 19.5; the mean score was significantly higher among patients with lower satisfaction.

Conclusions: The CTS-6 is highly responsive to change in symptoms, and the palmar pain scale is a valid measure of surgery-related pain. These brief scales can be appropriate primary and secondary outcomes measures in clinical trials studying carpal tunnel syndrome.