Clinical Course and Prognostic Factors in Conservatively Managed Carpal Tunnel Syndrome: A Systematic Review.

OBJECTIVE: To summarize the available evidence regarding the course of symptoms and prognostic factors in patients with diagnosed carpal tunnel syndrome (CTS) who are treated conservatively.

DATA SOURCES: Computerized databases, reference checking, and experts in the field were used to identify studies for inclusion in the review.

STUDY SELECTION: Multiple reviewers were used to identify studies which included adults (aged ≥18y) diagnosed with CTS in either a clinical setting or population setting. The study must have observed the course of CTS over at least a 6-week period in patients receiving no treatment or usual care that included conservative (nonsurgical) treatments. The design was of a longitudinal cohort study with either prospective or retrospective data collection. There were no language restrictions, and none of the research identified was only reported in abstract form.

DATA EXTRACTION: Methodological bias was assessed using the Quality in Prognosis Studies tool. A high risk of bias (predominantly relating to study attrition, confounding, and/or statistical analysis and reporting) was judged to be present in 8 studies. Designs showed wide variability with respect to characteristics of the included population, definition of CTS, assessment of prognostic factors, types of interventions provided, and types of outcome measures applied. This prevented pooled estimates from being produced.

DATA SYNTHESIS: A negative outcome at 3 years' follow-up of conservatively treated participants ranged from 23% to 89%. Four included studies observed the rate of surgical intervention after initial conservative management and found this to be 57% to 66%. Evidence regarding factors predicting the negative outcome of no treatment or conservative treatment was graded, taking into account the number of studies evaluating the factor, the methodological quality of these studies, and the consistency of the available evidence. There was 100% agreement in at least 3 cohorts with a medium or high risk of bias that symptom duration, a positive Phalen's test, and thenar wasting were associated with a negative outcome of conservative management; however, not all results were statistically significant, and hence the overall judgment remained inconclusive.

CONCLUSIONS: Results of this review should be treated with caution because of the heterogeneity of studies and the risks of bias identified. However, the course of CTS appears variable, and poor prognosis may be predicted by a longer symptom duration, a positive Phalen's test, and thenar wasting.