Association between Hoehn and Yahr, Mini-Mental State Examination, age, and clinical syndrome predominance and diagnostic effectiveness of ioflupane I 123 injection (DaTSCANTM) in subjects with clinically uncertain parkinsonian syndromes

INTRODUCTION: Diagnostic effectiveness of Ioflupane I 123 injection (DaTSCAN™, DaTscan™, or [123I]FP-CIT or ioflupane [(123)I]) SPECT imaging, was assessed in patients with clinically uncertain parkinsonian syndrome (CUPS). METHODS: We investigated the association between subject's Hoehn & Yahr (H&Y) stage, Mini-Mental State Examination (MMSE), age, and motor symptom subgroups and diagnostic performance of ioflupane [(123)I] imaging. Phase 4 study data were used to calculate sensitivity, specificity, positive and negative predictive value, and accuracy in 92 CUPS subjects, using 1-year clinical diagnosis after ioflupane [(123)I] imaging as reference standard. RESULTS: Diagnostic effectiveness of ioflupane [(123)I] imaging was high in all subgroups: 91% to 100% for H&Y low (<2) and high (≥2) stage subjects; 93% to 96% for MMSE low (<29) or high (≥29) scores; 91% to100% in both age subgroups (younger [<68] and older [≥68]); and 92% to 100% in subjects with both tremor dominant and balanced motor signs. Specificity of ioflupane [(123)I] imaging for bradykinetic rigid or posturally (BRP) unstable motor subtype was lower, but better than for baseline clinical diagnosis. CONCLUSIONS: Strongest diagnostic performance of ioflupane [(123)I] imaging for clinical diagnosis of Parkinson's syndrome (PS) or non-PS was associated with tremor and balanced motor dominance rather than with BRP dominance. High diagnostic effectiveness of ioflupane [(123)I] imaging and favourable performance relative to final clinical diagnosis at 1 year post-scan in subjects with CUPS was demonstrated. This study suggests that the diagnostic performance of ioflupane [(123)I] imaging in CUPS remains high at all stages of disease, including early stage, and across both age groups and cognitive state (MMSE).