The measure reflects the percent of patients receiving spine surgery who had a clinically significant issue of urinary retention (residual urine in bladder after voiding, or inability to void) in the immediate post-surgical period. Rates are reported on a risk-adjusted basis, with the risk adjustment model based on a set of demographic and clinical characteristics, as well as case-mix variables (e.g., fusion vs. non-fusion) so that rates are truly comparable from surgeon to surgeon.