Cost-effectiveness of functional imaging tests in the diagnosis of Alzheimer disease.

PURPOSE To evaluate the cost-effectiveness of functional neuroimaging in the work-up of patients at specialized Alzheimer disease clinics. MATERIALS AND METHODS A decision model was used to calculate costs and benefits (in quality-adjusted life-years [QALYs]) that accrued to hypothetical cohorts of patients at presentation to an Alzheimer disease center. Sensitivity analysis was performed to examine the effects of diagnostic test characteristics, therapeutic efficacy, disease severity, and costs on cost-effectiveness. RESULTS The incremental cost-effectiveness ratio of dynamic susceptibility contrast material-enhanced magnetic resonance (MR) imaging was $479,500 per QALY (compared with the usual diagnostic work-up), while visual or quantitative single photon emission computed tomography (SPECT) was dominated (higher costs, lower effectiveness) by the usual diagnostic work-up. These results depend critically on the sensitivity and specificity of the standard diagnostic work-up, the effectiveness of drug treatment, and the disease severity. Varying these parameters resulted in estimates of incremental cost-effectiveness for dynamic susceptibility contrast-enhanced MR imaging of $24,680 to $8.6 million per QALY. SPECT either was dominated by the usual diagnostic work-up or had cost-effectiveness ratios of $180,200 to $6 million per QALY. CONCLUSION The addition of functional neuroimaging to the usual diagnostic regimen at Alzheimer disease clinics is not cost-effective given the effectiveness of currently available therapies.