Cost-effectiveness of microprocessor-controlled prosthetic knees in the Dutch healthcare system: The impact of study duration on outcomes.

A previous health-utility analysis of microprocessor-controlled prosthetic knees (MPKs) in the Netherlands used a very short evaluation period of only 6 months resulting in an extremely high incremental cost-utility ratio (ICUR) of €457,063 per quality-adjusted life year (QALY) gained. However, for proper health-economic analyses, an appropriate time horizon, usually the useful life of an intervention, must be chosen to avoid biased results. Therefore, we performed a basic cost-utility analysis (CUA) extrapolating and properly discounting the utility and cost data reported by that article over the useful lifetime of MPKs of 6 years and found an ICUR of €17,945 per QALY. To further refine the CUA, we conducted a modeling study of the ICUR of the MPKs over a timeframe from 6 months to 25 years using existing and published population models for Germany and Sweden. In the modeling study, the ICUR was higher for the Netherlands with €37,567 per QALY than for Germany (€18,276 per QALY) or Sweden (€11,147 per QALY) but below the Dutch threshold for willingness to pay of €50,000 per QALY for people with a lower-limb amputation. Thus, the MPKs were cost-effective for the Dutch healthcare system in all scenarios of the cost-utility analysis. Our analysis showed that time had a much bigger impact on the ICUR than utility with the MPKs becoming cost-effective with the ICUR falling below the €50,000-per-QALY threshold after 4-5 years of use. Thus, a proper time horizon covering the useful lifetime of an intervention is key for health-economic analyses to prevent potentially misleading results and unjustified detrimental decisions for patients.