RESEARCH REPORT POSTER DISPLAY

THE SF-6D HEALTH UTILITY INDEX IN CARPAL TUNNEL SYNDROME. Gummesson C¹, Atroshi I², McCabe S³, Ornstein E²; ¹Division of Physiotherapy, Lund University,Lund, Sweden. ²Department of Orthopedics, Hässleholm Hospital, Hässleholm, Sweden. ³School of Public Health, University of Louisville, Louisville, Kentucky USA

PURPOSE: Health utility measures are used to estimate quality-adjusted life years that in combination with the costs of various treatments provide a measure of their cost-effectiveness. Conventional (direct) utility measures determine health preferences with complex techniques (standard gamble and time trade-off). Multi-attribute (indirect) utility measures (SF-6D and EQ-5D) are quality-of-life measures with predetermined preference weights for different health states derived from large general population samples (US, UK, Europe). The SF-6D, derived from 11 items of the SF-36, covers 6 health dimensions and describes 18,000 possible health states; health state values ranging from 1.0 (full health, no problem with any dimension) to 0.296 (most severe problems with all 6 dimensions). The EQ-5D (5 items) covers 5 dimensions and describes 243 possible health states (values from 1.0 to −0.109). These utility measures have not been used in hand disorders. The aim was to assess validity of the SF-6D health utility index in patients with carpal tunnel syndrome (CTS) and determine health utilities for CTS before and after surgery. RELEVANCE: Utility measures can add important information in outcome assessment, but is to date sparsely used. PARTICIPANTS: In a prospective cohort study 95 patients with CTS completed the SF-36 and the validated CTS questionnaire (symptom severity and functional status scales) before and 3 months after surgery. METHODS: Responses to the 11 SF-6D items were complete in 100 patients at baseline and 95 patients on both occasions. The EQ-5D index was derived from simulated (SF-36 based) responses to EQ-5D items. ANALYSIS: SF-6D and EQ-5D indices were computed using specific algorithms. CTS symptom severity and functional status scores calculated, effect size (mean score change from baseline to 3 months divided by standard deviation of baseline score) and standardized response mean (mean baseline to 3 months score change divided by standard deviation of score change) were calculated. The SF-6D scores between the improved vs fair/poor change were compared with the t-test. RESULTS: The mean SF-6D index was 0.69 (SD 0.13) before and 0.77 (SD 0.13) after surgery and the mean EQ-5D index was 0.61 and 0.75, respectively; an improvement corresponding to moderate effect size. The SF-6D could discriminate among patients differing in self-rated health and in whether they had a minimal clinically important improvement in CTS symptom severity score (P < 0.01). CONCLUSIONS: The SF-6D can be used as a valid utility measure in cost-effectiveness studies in CTS. IMPLICATIONS: SF-6D and EQ-5D has the potential to be used to show cost effectiveness of different physical therapy interventions. KEYWORDS: Outcome measures, Utility measures. FUNDING ACKNOWLEDGEMENTS: Region Skane, Sweden.