Stratified cost-utility analysis of C-Leg versus mechanical knees: Findings from an Italian sample of transfemoral amputees.

BACKGROUND: The fitting rate of the C-Leg electronic knee (Otto-Bock, D) has increased steadily over the last 15 years. Current cost-utility studies, however, have not considered the patients' characteristics.

OBJECTIVES: To complete a cost-utility analysis involving C-Leg and mechanical knee users; "age at the time of enrollment," "age at the time of first prosthesis," and "experience with the current type of prosthesis" are assumed as non-nested stratification parameters.

STUDY DESIGN: Cohort retrospective.

METHODS: In all, 70 C-Leg and 57 mechanical knee users were selected. For each stratification criteria, we evaluated the cost-utility of C-Leg versus mechanical knees by computing the incremental cost-utility ratio, that is, the ratio of the "difference in cost" and the "difference in utility" of the two technologies. Cost consisted of acquisition, maintenance, transportation, and lodging expenses. Utility was measured in terms of quality-adjusted life years, computed on the basis of participants' answers to the EQ-5D questionnaire.

RESULTS: Patients over 40 years at the time of first prosthesis were the only group featuring an incremental cost-utility ratio (88,779 €/quality-adjusted life year) above the National Institute for Health and Care Excellence practical cost-utility threshold (54,120 €/quality-adjusted live year): C-Leg users experience a significant improvement of "mobility," but limited outcomes on "usual activities," "self-care," "depression/anxiety," and reduction of "pain/discomfort."

CONCLUSION: The stratified cost-utility results have relevant clinical implications and provide useful information for practitioners in tailoring interventions. Clinical relevance A cost-utility analysis that considered patients characteristics provided insights on the "affordability" of C-Leg compared to mechanical knees. In particular, results suggest that C-Leg has a significant impact on "mobility" for first-time prosthetic users over 40 years, but implementation of specific low-cost physical/psychosocial interventions is required to retun within cost-utility thresholds.