Carpal tunnel syndrome: cross-sectional and outcome study in Ontario workers

To carry out an analytic cross-sectional study of Ontario workers with carpal tunnel syndrome (CTS) and to assess workers' symptoms, functional disabilities, recreational difficulties, and work capability 4 years after treatment of their CTS.

Data were obtained by review of Ontario Workers Safety and Insurance Board (WSIB) files and by completion of self-assessment questionnaires. Inclusion criteria included all workers registered with the Ontario WSIB who were off work with newly diagnosed carpal tunnel syndrome in 1996.

There are 3 million workers covered by the WSIB in the province of Ontario. In 1996, 964 of them developed work-related CTS that required time off for treatment. Of these patients 53% were women and 75% had bilateral CTS. Eighty-one percent of the unilateral cases involved the dominant extremity. The average age at the time of claim was 41 years and workers were at the same job type for an average of 7.4 years (unilateral) and 8.5 years (bilateral), respectively. Thirty-nine percent of workers had a history of another tendonitis or epicondylitis. Seventy-five percent of workers had surgery and on average returned to work 3 months later. Four years after treatment, outcome was assessed by self-administered questionnaires, for which there was a 73% response rate. Forty-six percent of workers experienced moderate to severe pain, 47% had moderate to severe numbness, and 40% had difficulty grasping and using small objects. Only 14% were symptom free. Successful return to work was considered to be a return to the same job with or without modifications, and it occurred in 64% of cases. Better clinical outcome scores were found to occur with surgery and abnormal nerve conduction study results. Worse clinical outcome scores were present with repeat surgery and surgical complications. Concurrent diagnoses of either tendonitis or epicondylitis also resulted in worse clinical outcome scores and worse return-to-work outcomes. The average total cost in Canadian dollars to the WSIB exceeded $13,700 per worker for a total cost in excess of $13,200,000 per year. (In 1996, $1 Canadian = $1.365 US.)

These outcomes indicate that Canadian workers have a large amount of permanent pain and suffering, a large loss of work productivity, and incur a considerable financial cost as a result of work-related CTS.