Risk factors for idiopathic cubital tunnel syndrome : development and surgical intervention from a nationwide population-based cohort study.

Aims: The aim of this nationwide population-based cohort study was to identify the risk factors associated with the development of idiopathic cubital tunnel syndrome (CuTS), and the factors which influence the requirement for surgery in these patients. Methods: We analyzed data from 43,189 patients newly diagnosed with idiopathic CuTS between January 2009 and December 2021, using the Korean National Health Insurance Service database. They were identified using diagnostic codes, procedural codes for surgery, and/or electrodiagnostic study codes. Patients with cervical radiculopathy, brachial plexopathy, polyneuropathy, previous CuTS and recent fracture, dislocation, or arthroplasty of the elbow were excluded. Age- and sex-matched controls were selected at a 1:5 ratio. Logistic regression identified risk factors for the development of CuTS, and Cox proportional hazards regression determined factors associated with surgical treatment. A false discovery rate-adjusted p-value < 0.05 was considered significant. Results: Risk factors for the development of CuTS included carpal tunnel syndrome (CTS), arthritis of the elbow, rheumatoid arthritis (RA), gout, depression, dyslipidaemia, hypertension, obesity, metabolic syndrome, diabetes, current smoking, anaemia, and hazardous alcohol drinking, in decreasing order of odds ratios. A total of 7,810 patients (18%) underwent surgery. Factors associated with surgery included CTS, arthritis of the elbow, RA, hypertension, obesity, metabolic syndrome, diabetes, current smoking, and hazardous alcohol drinking, in decreasing order of hazard ratios. Regular exercise significantly reduced the risk of both the development of CuTS and the requirement for surgery. Conclusion: In this large cohort study, we identified risk factors for the development of idiopathic CuTS and its surgical treatment, many of which parallel those for CTS. These findings may guide clinicians in risk stratification, prevention, and management of patients with idiopathic CuTS, and provide insights into the shared aetiology.