Predicting surgical intervention in patients presenting with carpal tunnel syndrome in primary care

Problem

Carpal tunnel syndrome (CTS) is a symptomatic compression neuropathy of the median nerve at the level of the wrist. This study aimed to investigate the predictive value of candidate prognostic factors available in primary care consultation data, to predict (the first occurrence of) carpal tunnel release surgery, as an indicator of poor outcome of conservative management deliverable in primary care. Such information could be used to inform and improve the management of patients with this common condition.

Approach

This study is a retrospective cohort study of patients presenting with an incident episode of CTS and is set in the Clinical Practice Research Datalink (CPRD). Individuals over the age of 18 years, with evidence of an incident diagnosis of CTS and at least 2 years of acceptable data preceding the diagnosis, were identified between 1989 and 2013. Candidate prognostic factors (PF) defined in coded patient records were identified following literature review and consultation with clinicians and were grouped by patient demographics, comorbidities and lifestyle. Time to first carpal tunnel release surgery (CTR) was the primary outcome.The strength of the association of each candidate PF with outcome was described using univariable Cox regression analysis. A manual backward stepwise selection procedure was used to obtain an optimal prediction model, which included all the significant (p < 0.1) PF’s. The model adjusted for region and deprivation.

Findings

91,420 patients were included in the cohort. 63,194 (69.1%) were female and the median age at diagnosis of the cohort was 53.5 (IQR 42.4 – 65.9) years. 21,392 (23.4%) of patients received surgery over the 24 year observed period. The median time to surgery was 266 days (IQR 126 – 588). Preliminary results indicate that the following variables are included in an optimal model for predicting surgical intervention: age (HR 1.01 per year, 95% confidence interval 1.01 – 1.01); female (HR 1.05, 95%CI 1.02 – 1.09); alcohol drinker (HR 0.96, 95%CI 0.92 – 0.99); smoker, (HR 1.05, 95%CI 1.02 – 1.08); pregnancy (HR 0.41, 95%CI 0.36 – 0.45); diabetes (HR 1.11, 95%CI 1.01 – 1.21); a further neck or upper limb condition (HR 1.11, 95%CI 1.03 – 1.21) and multi-site pain (HR 1.10, 95%CI 1.05 – 1.16).

Consequences

This study suggests that patients presenting with CTS during or within a year of pregnancy are less likely to have surgery at any time during follow-up, whereas older patients, women, and patients with comorbidities including diabetes are more likely to have surgery. This information can help to inform clinicians and patients about the likely outcome of treatment and to be aware of which patients may be less responsive to primary care interventions. However, the results are likely to be influenced by confounding by indication and variability in access to surgical intervention. Further research, using patient reported outcomes, will provide additional insight into the prognosis of CTS.