The quality of electrodiagnostic tests for carpal tunnel syndrome: Implications for surgery, outcomes, and expenditures.

Introduction: The quality of electrodiagnostic tests may influence treatment decisions, particularly regarding surgery, affecting health outcomes and health-care expenditures.
Methods: We evaluated test quality among 338 adults with workers' compensation claims for carpal tunnel syndrome. Using simulations, we examined how it influences the appropriateness of surgery. Using regression, we evaluated associations with symptoms and functional limitations (Boston Carpal Tunnel Questionnaire), overall health (12-item Short Form Health Survey version 2), actual receipt of surgery, and expenditures.
Results: In simulations, suboptimal quality tests rendered surgery inappropriate for 99 of 309 patients (+32 percentage points). In regression analyses, patients with the highest quality tests had larger declines in symptoms (-0.50 point; 95% confidence interval [CI], -0.89 to -0.12) and functional impairment (-0.42 point; 95% CI, -0.78 to -0.06) than patients with the lowest quality tests. Test quality was not associated with overall health, actual receipt of surgery, or expenditures.
Discussion: Test quality is pivotal to determining surgical appropriateness and associated with meaningful differences in symptoms and function.
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