Valuing postoperative recovery: validation of the SF-6D health-state utility.
BACKGROUND
Many surgical innovations are costly but may result in faster patient recovery. Economic analyses of these innovations require utility measures that reflect the construct of "postoperative recovery." We investigated the validity of Short Form 6D (SF-6D) utility value as a measure of postoperative recovery in patients undergoing elective colorectal resection.


MATERIALS AND METHODS
Patients undergoing elective colorectal resection completed the Short Form 36 and the 6-min walk test at baseline (before surgery) and at 4 and 8 wk postoperatively. SF-6D utilities were derived from the Short Form 36. Longitudinal validity (responsiveness) was assessed using standardized response means (SRM). Construct validity was assessed by comparing the difference in mean SF-6D between patients with and without complications (discriminant) and by correlating the SF-6D with other measures of recovery (convergent).


RESULTS
A total of 191 patients were included (58% male; mean age 63.0 (SD 14.2) y, 81% malignancy, and 54% laparoscopic). SF-6D values dropped significantly from baseline to 4 wk after surgery (SRM -0.54, P < 0.001) and returned to baseline by 8 wk (SRM -0.12, P = 0.111). At 4 wk after surgery, the SF-6D was lower in patients with complications than in those without (mean difference -0.047, 95% CI -0.088, -0.006). At all time points, the SF-6D correlated significantly with the physical and mental component scales of the SF-36 (Pearson r 0.67-0.80, all P < 0.001) and the 6-min walk test (r 0.21-0.29, all P < 0.05).


CONCLUSIONS
The SF-6D is a valid measure of postoperative recovery following elective colorectal resection and may be used to measure quality-adjusted life years for cost-effectiveness analyses of surgical technologies and interventions hypothesized to impact recovery.