Wolk DA, et al. - In this multicenter cohort study, researchers assessed the ability of flutemetamol F 18 and other biomarkers to evaluate the risk of progression from amnestic mild cognitive impairment (aMCI) to probable Alzheimer disease (AD), given that current research now accepts that a combination of biomarkers could provide greater refinement in the assessment of risk for clinical progression. A high probability of risk of progression from aMCI to probable AD within 36 months was suggested by a combination of positive results of flutemetamol F 18–labeled positron emission tomography (PET), low hippocampal volume, and cognitive status.

Methods

• This study was performed from November 11, 2009, to January 16, 2014.
• During this period, patients with aMCI had positron emission tomography (PET) at baseline followed by local clinical assessments every 6 months for up to 3 years.
• For this study, researchers recruited patients with aMCI (365 screened; 232 were eligible) from 28 clinical centers in Europe and the United States.
• Physicians continued to be strictly blinded to the results of PET.
• Local assessments were confirmed or refuted by the standard of truth, which was an independent clinical adjudication committee.
• Five blinded readers with no knowledge of clinical status read centrally flutemetamol F 18–labeled PET scans as either negative or positive.
• From February 19, 2014, to January 26, 2018, statistical analysis was carried out.
• Interventions included flutemetamol F 18–labeled PET at baseline followed by up to 6 clinical visits every 6 months, as well as magnetic resonance imaging and multiple cognitive measures.
• Plotting of time from PET to probable AD or last follow-up was done, as a Kaplan-Meier survival curve; Cox proportional hazards logistic regression analyses including PET scan results, age, hippocampal volume, and aMCI stage, were used to identify variables related to progression to probable AD.

Results

• Positive results on PET scan were seen in 98 (42.2%) of 232 patients with aMCI (118 women and 114 men; mean [SD] age, 71.1 [8.6] years).
• According to findings, the rates of progression to probable AD by 36 months were 36.2% overall (81 of 224 patients), 53.6% (52 of 97) for patients with positive results detected on PET scan, and 22.8% (29 of 127) for patients with negative results detected on PET scan.
• Data revealed that, 2.51 (95% CI, 1.57-3.99; P<.001) were the hazard ratios for association with progression when assessed for a positive β-amyloid scan alone (primary outcome measure), these were noted to be 5.60 (95% CI, 3.14-9.98; P<.001) with additional low hippocampal volume, and 8.45 (95% CI, 4.40-16.24; P<.001) when poorer cognitive status was added to the model.