Carpal tunnel release surgery: small-area variation and impact of ambulatory surgery in the autonomous region of Valencia, Spain.

Objective: This study aimed to analyze variability in rates of carpal tunnel release surgery among the healthcare areas of the autonomous region of Valencia, and to evaluate the contribution of ambulatory surgery and referrals to private hospitals to the variability found.

Methods: We carried out a cross-sectional, population-based study, describing the rates of carpal tunnel release surgery, standardized by age and sex, among areas in the region of Valencia in 2006. The observed variation was then analyzed using small-area analysis methods. Data from hospital admissions, referrals to private hospitals, population statistics and hospital resources were used to construct standardized rates, and Spearman's correlation was used to test the association with surgical setting and hospital resources.

Results: There were 8.2 carpal tunnel release surgeries per 10,000 inhabitants in the region of Valencia in 2006. Most (88.2%) of these interventions were performed as ambulatory surgery. After we excluded areas outside the 5th-95th percentiles, variation among areas was moderate and was similar for men and women. Variation was not associated with the proportion of the distinct surgical settings (admission to a public hospital, outpatient clinic, or referral to a private hospital) used in each area, or with the availability of resources.

Conclusions: Variation in carpal tunnel release surgery among areas in the region of Valencia is moderate, but has a strong impact on the population because of the high prevalence of this disorder. This variation is not explained by the hospital resources available in each area or the surgical setting.