Abstract
481
Objectives: Our initial study found that patients undergoing PET diagnostics for cognitive impairment showed a longer survival duration if they were β-amyloid (Aβ)-positive on PIB PET. In the present study we investigated (i) if previous results are also confirmed after a longer follow-up and (ii) if the combination of FDG and PIB PET can bring greater detail to our findings. Methods: In the present analysis we included patients from our clinical registry who received PIB and FDG PET scans for diagnostics of cognitive impairment between 05/2009 and 06/2016. Vital status information was obtained in 07/2017. Patients were grouped based on clinical PET reports (see below). Survival data was analyzed by Cox regression models, adjusted for sex and age. Results: The vital status of 252/262 patients could be determined. The lower mortality risk of Aβ-positive patients was confirmed (HR = 0.5 [0.27-0.9], p < 0.05). Based on the combined clinical PIB and FDG PET reports, patients were stratified into three major groups: Normal PIB and FDG PET scans (NS; n = 35), Alzheimer´s disease (AD; n = 121) and frontotemporal lobar degeneration (FTLD; n = 55). The remaining patients (n = 41) were distributed across smaller subgroups lacking sufficient size for analysis. After a median follow-up of 3.8, 4.4 and 4.0 years, 5 (14 %), 17 (14 %) and 15 (27 %) of NS, AD and FTLD patients died, respectively. Patients diagnosed with AD by combined PIB and FDG PET showed a significantly lower mortality risk than patients diagnosed with FTLD (HR = 0.4 [0.21-0.88], p < 0.05). Results were confirmed after exclusion of all Aβ-positive FTLD patients (n = 5) and after adjustment for Mini-Mental State Examination (MMSE) (available in n = 170). There were now other significant findings. Conclusions: In line with clinicopathological studies we found a shorter survival for patients diagnosed with FTLD, which explains the somewhat surprising result of relatively longer survival for Aβ-positive patients with cognitive impairment.