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Dopamine transporter imaging and SPECT in diagnostic work-up of Parkinson's disease: A decision-analytic approach



As a diagnostic test for patients with suspected Parkinson's disease (PD), single photon emission computed tomography (SPECT) using [123I]FP-CIT tracer has better sensitivity but is more expensive than regular clinical examination (CE). Our objective was to evaluate the clinical and economic impacts of different diagnostic strategies involving [123I]FP-CIT SPECT. We developed a decision tree model to predict adequate treatment-month equivalents (ATME), costs, and incremental cost–effectiveness ratio (ICER) during a 12-month time horizon in patients with suspected PD referred to a specialized movement disorder outpatient clinic. In our cost– effectiveness analysis, we adopted the perspective of the German health care system and used data from a German prospective health care utilization study (n = 142) and published diagnostic studies. Compared strategies were CE only (EXAM+), SPECT only (SPECT+), SPECT following negative CE (SINGLE+), and SPECT following positive CE (DOUBLE+). Costs of SPECT amounted to €789 per investigation. Based on our model, expected costs (and ATME) were €946 (52.85 ATME) for EXAM+, €1352 (53.40 ATME) for DOUBLE+, €1731 (32.82 ATME) for SINGLE+, and €2003 (32.96 ATME) for SPECT+; performance of SPECT was induced in 0%, 54%, 56%, and 100% of the patients, respectively. DOUBLE+ was more effective and less expensive than SINGLE+ or SPECT+; thus these two do not offer reasonable choices. The ICER of DOUBLE+ compared to EXAM+ was €733 per ATME gained. In sensitivity analyses, the ICER of DOUBLE+ versus EXAM+ ranged from €63 to €2411 per ATME gained. Whether the diagnostic work-up of patients referred to a specialized movement disorder clinic with a high prevalence of PD should include [123I]FP-CIT SPECT depends on patient preferences and the decision maker's willingness to pay for adequate early treatment. SPECT should be used as a confirmatory test before treatment initiation and limited to patients with a positive test result in the clinical examination. These results should be adjusted to the specific setting and individual patient preferences. © 2003 Movement Disorder Society