Analytical approach:
A retrospective review of medical records was conducted to assess the long-term costs and benefits of FES. Follow-up assessments were conducted for as long as the device was used (mean 4.9 years). The perspective was not stated.
Effectiveness data:
The key effectiveness outcome was the change in 10 metre walking speed. This was from the retrospective review of the records of 126 patients who were referred for treatment by a general practitioner or medical consultant. Patients began treatment in 1999 and were suffering from stroke, multiple sclerosis, spinal cord injury, cerebral palsy, or unspecified conditions. Four comparisons were used: the initial orthotic effect (with FES, end versus start of first day); the total orthotic effect (with FES, follow-up versus start); the training effect (without FES, follow-up versus start); and continuing orthotic effect (with versus without FES, at follow-up). Walking speed was measured at six, 18 and 42 weeks, and then every six or 12 months for as long as the device was used. The clinical utility of the change in walking speed was measured as the number of patients who changed functional walking category in the first 16.5 months of treatment (last point at which data were available for all patients).
Monetary benefit and utility valuations:
An estimate of the utility gain associated with FES per year was derived from an economic report produced by the UK's Purchasing and Supply Agency, in 2010. The gain was calculated by translating the proportion of FES users crossing key walking speed thresholds to changes in the Health Utilities Index (HUI3). This calculation took account of the number of FES users with reduced utility due to skin reaction to the electrodes.
Measure of benefit:
The health benefit was measured by increased walking speed and quality-adjusted life-years (QALYs).
Cost data:
The costs were calculated using hospital tariffs, for each clinic assessment. These included all device, consumables and clinical costs. They were reported in 2012 UK £.
Analysis of uncertainty:
The variation in estimates was presented as standard deviations and 95% confidence intervals.