Prevalence and Risk Factors of Carpal Tunnel Syndrome in Japanese Aged 50 to 89 Years

Background: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy worldwide, but there are few reports investigating its prevalence using subjects diagnosed by both clinical symptoms and nerve conduction studies (NCSs) in a population-based cohort. This study aimed to determine the epidemiology of CTS diagnosed by sensory disturbance findings and NCSs using a randomly sampled resident population. Methods: Subjects aged between 50 and 89 years were randomly sampled from the basic resident registry of a rural Japanese town. Subjects indicating a history of CTS surgery in a written questionnaire were classified as having past CTS. Subjects with both sensory disturbance of the median nerve area and delays in NCSs were diagnosed as having present CTS. Subjects with past or present CTS were judged as affected with CTS. We calculated the prevalence of CTS and investigated for possible risk factors. Results: Seventeen subjects (14 female and 3 male) were affected with CTS among 379 enrolled subjects. Adjusting these results to Japanese population values, the weighted prevalence of CTS was 4.7% (female: 7.2%, male: 1.8%) in the Japanese population aged 50 to 89 years. Statistically significant positive correlations were found between CTS and female, higher BMI, rheumatoid arthritis, and trigger digit. In females affected with CTS, third metacarpal length was significantly shorter than in those without CTS. Conclusions: This epidemiological study clarified the prevalence of CTS among Japanese seniors as 4.7%. Female, higher BMI, rheumatoid arthritis, trigger digit, and shorter third metacarpal length in females were risk factors for CTS.