Development and validation of a clinical model for predicting the severity of carpal tunnel syndrome

Behnaz Aalaie; Javad Sadeghi; Tanya Mohammadi; Babak Mohammadi

doi:10.1093/mr/road076

Development and validation of a clinical model for predicting the severity of carpal tunnel syndrome

Mod Rheumatol. 2023 Jul 31:road076. doi: 10.1093/mr/road076. Online ahead of print.

Authors

Behnaz Aalaie¹, Javad Sadeghi², Tanya Mohammadi³, Babak Mohammadi⁴

Affiliations

¹ Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Hamadan University of Medical Sciences and Health Services, Hamadan, Iran.
² Pain Clinic Manager, Be'sat Hospital, Faculty of Medicine, Aja University of Medical Sciences, Tehran, Iran.
³ School of Mathematics, Statistics, and Computer Science, College of Science, University of Tehran, Tehran, Iran.
⁴ Independent Scholar, Tehran, Iran.

PMID: 37522621
DOI: 10.1093/mr/road076

Abstract

Objectives: Pain, discomfort, and cost may result in incomplete or inconclusive electrodiagnostic studies to assess the severity of carpal tunnel syndrome. We aimed to develop a clinical instrument for stratifying patients based on easy-to-measure variables to assess carpal tunnel syndrome severity.

Methods: We performed a secondary analysis of data from patients diagnosed with a diagnosis of carpal tunnel syndrome using a factor analysis of mixed data. In total, 1037 patients (405; 39.1% male) with a mean (SD) age of 58.0 (10.8) years were included. For each patient, demographic information, physical examination findings, ultrasonographic findings, and the severity of the syndrome based on electrodiagnostic studies were recorded.

Results: We devised a composite index incorporating a pain numeric rating scale (NRS) rated from 0 (no pain at all) to 10 (the worst pain ever possible), presence of thenar muscle weakness or atrophy (TW), cross-sectional area (CSA) of the median nerve (mm2), and occurrence of nocturnal pain (NP). The composite index was calculated as [scale(NRS)+scale(CSA)+NP+TW]/4, where both NP and TW are binary features (0 or 1). The overall accuracy and area under the curve of the index for stratifying the syndrome severity were 0.85 and 0.71, respectively (Cohen's Kappa = 0.51, McNemar's test P = 0.249). The composite index increased pretest probability by 1.6, 1.8, and 3.3 times with positive likelihood ratios of 3.3, 2.5, and 13.5, and false-positive rates of 26.6, 17.6, and 4.8% for mild, moderate, and severe syndrome, respectively. The index thresholds for mild, moderate, and severe carpal tunnel syndrome were <0.8, ≥0.8 to <1.1, and ≥1.1, respectively.

Conclusion: Using a composite index, patients with carpal tunnel syndrome can be categorized for the severity of the syndrome before carrying out electrodiagnostic studies.

Keywords: Carpal Tunnel; Electrodiagnosis; Median; Pain; Severity; Thenar Atrophy.