18 F‐florbetaben uptake by brain tissue, measured by positron emission tomography
(PET), is accepted by regulatory agencies like the Food and Drug Administration (FDA)
and the European Medicine Agencies (EMA) for assessing amyloid load in people with
dementia. Its added value is mainly demonstrated by excluding Alzheimer's pathology
in an established dementia diagnosis. However, the National Institute on Aging and
Alzheimer's Association (NIA‐AA) revised the diagnostic criteria for Alzheimer's disease
and confidence in the diagnosis of mild cognitive impairment (MCI) due to Alzheimer's
disease may be increased when using some amyloid biomarkers tests like 18 F‐florbetaben.
These tests, added to the MCI core clinical criteria, might increase the diagnostic
test accuracy (DTA) of a testing strategy. However, the DTA of 18 F‐florbetaben to
predict the progression from MCI to Alzheimer’s disease dementia (ADD) or other dementias
has not yet been systematically evaluated. To determine the DTA of the 18 F‐florbetaben
PET scan for detecting people with MCI at time of performing the test who will clinically
progress to ADD, other forms of dementia (non‐ADD), or any form of dementia at follow‐up.
The most recent search for this review was performed in May 2017. We searched MEDLINE
(OvidSP), Embase (OvidSP), PsycINFO (OvidSP), BIOSIS Citation Index (Thomson Reuters
Web of Science), Web of Science Core Collection, including the Science Citation Index
(Thomson Reuters Web of Science) and the Conference Proceedings Citation Index (Thomson
Reuters Web of Science), LILACS (BIREME), CINAHL (EBSCOhost), ClinicalTrials.gov (
https://clinicaltrials.gov ), and the World Health Organization International Clinical
Trials Registry Platform (WHO ICTRP) ( http://www.who.int/ictrp/search/en/ ). We also
searched ALOIS, the Cochrane Dementia & Cognitive Improvement Group’s specialised
register of dementia studies ( http://www.medicine.ox.ac.uk/alois/ ). We checked the
reference lists of any relevant studies and systematic reviews, and performed citation
tracking using the Science Citation Index to identify any additional relevant studies.
No language or date restrictions were applied to electronic searches. We included
studies that had prospectively defined cohorts with any accepted definition of MCI
at time of performing the test and the use of 18 F‐florbetaben scan to evaluate the
DTA of the progression from MCI to ADD or other forms of dementia. In addition, we
only selected studies that applied a reference standard for Alzheimer’s dementia diagnosis,
for example, the National Institute of Neurological and Communicative Disorders and
Stroke and the Alzheimer’s Disease and Related Disorders Association (NINCDS‐ADRDA)
or Diagnostic and Statistical Manual of Mental Disorders‐IV (DSM‐IV) criteria. We
screened all titles and abstracts identified in electronic‐database searches. Two
review authors independently selected studies for inclusion and extracted data to
create two‐by‐two tables, showing the binary test results cross‐classified with the
binary reference standard. We used these data to calculate sensitivities, specificities,
and their 95% confidence intervals. Two independent assessors performed quality assessment
using the QUADAS‐2 tool plus some additional items to assess the methodological quality
of the included studies. Progression from MCI to ADD, any other form of dementia,
and any form of dementia was evaluated in one study (Ong 2015). It reported data on
45 participants at four years of follow‐up; 21 participants met NINCDS‐ADRDA criteria
for Alzheimer’s disease dementia at four years of follow‐up, the proportion converting
to ADD was 47% of the 45 participants, and 11% of the 45 participants met criteria
for other types of dementias (three cases of FrontoTemporal Dementia (FTD), one of
Dementia with Lewy body (DLB), and one of Progressive Supranuclear Palsy (PSP)). We
considered the study to be at high risk of bias in the domains of the reference standard,
flow, and timing (QUADAS‐2). MCI to ADD ; 18 F‐florbetaben PET scan analysed visually:
the sensitivity was 100% (95% confidence interval (CI) 84% to 100%) and the specificity
was 83% (95% CI 63% to 98%) (n = 45, 1 study). Analysed quantitatively: the sensitivity
was 100% (95% CI 84% to 100%) and the specificity was 88% (95% CI 68% to 97%) for
the diagnosis of ADD at follow‐up (n = 45, 1 study). MCI to any other form of dementia
(non‐ADD); 18 F‐florbetaben PET scan analysed visually: the sensitivity was 0% (95%
CI 0% to 52%) and the specificity was 38% (95% CI 23% to 54%) (n = 45, 1 study). Analysed
quantitatively: the sensitivity was 0% (95% CI 0% to 52%) and the specificity was
40% (95% CI 25% to 57%) for the diagnosis of any other form of dementia at follow‐up
(n = 45, 1 study). MCI to any form of dementia ; 18 F‐florbetaben PET scan analysed
visually: the sensitivity was 81% (95% CI 61% to 93%) and the specificity was 79%
(95% CI 54% to 94%) (n = 45, 1 study). Analysed quantitatively: the sensitivity was
81% (95% CI 61% to 93%) and the specificity was 84% (95% CI 60% to 97%) for the diagnosis
of any form of dementia at follow‐up (n = 45, 1 study). Although we were able to calculate
one estimation of DTA in, especially, the prediction of progression from MCI to ADD
at four years follow‐up, the small number of participants implies imprecision of sensitivity
and specificity estimates. We cannot make any recommendation regarding the routine
use of 18 F‐florbetaben in clinical practice based on one single study with 45 participants.
18 F‐florbetaben has high financial costs, therefore, clearly demonstrating its DTA
and standardising the process of the 18 F‐florbetaben modality are important prior
to its wider use. 18 F PET with florbetaben for the early diagnosis of Alzheimer's
disease dementia and other dementias in people with mild cognitive impairment Review
question: In people with mild cognitive impairment (MCI), does using a 18 F PET
scan with florbetaben predict progression to Alzheimer's disease dementia (ADD) and
other dementias? Background
Due to global ageing, the number of people with dementia is expected to increase dramatically
in the next few decades. Diagnosing dementia at an early stage is desirable, but there
is no widespread agreement on the best approach. A range of simple pen and paper tests
used by healthcare professionals can assess people with poor memory or cognitive impairment.
Whether or not using special PET scans that detect amyloid —one of the hallmarks of
Alzheimer's disease— improves our ability to predict the progression from MCI to ADD
or other forms of dementia remains unclear. Since these tests are expensive, it is
important that they provide additional benefits. Aim We aimed to evaluate the accuracy
of the 18 F‐florbetaben PET scan in identifying those people with MCI who clinically
progress to ADD, other types of dementia, or any form of dementia over a period of
time. Study characteristics
The evidence is current to May 2017. We found 1 study including 45 participants with
MCI with a follow‐up of 4 years; gender was not reported and the median age for those
with a PET‐positive scan by quantitative assessment was 73.5 years old. For those
with a PET‐negative scan the mean age was 71.8 years old. Participants were mainly
recruited from local memory clinics. Study funding sources: the study was funded by
the test manufacturer. Quality of the evidence
The main limitation of this review was that our findings were based on only one study,
with not enough details on how the participants were selected. The study was considered
to be at high risk of bias, since the final ADD diagnosis was not established separately
from the scan results, and due to potential conflicts of interest detected. Key findings
In this review, based on only one study, we found that the 18 F‐florbetaben PET scan,
as a single test with visual assessment, correctly classified 100% of the participants
who will progress to ADD and 83% of the participants who did not progress to ADD at
four years follow‐up. This means that in a cohort with 100 participants with MCI,
47 of whom will progress to ADD, we would expect that all those 47 MCI participants
would test positive with the 18 F‐florbetaben scan and that 0 participants would
be falsely negative (i.e. none of the 47 participants would have a negative test and
yet progress to ADD). In addition, we would expect 44 of 53 participants who did not
progress to ADD to be 18 F‐florbetaben‐negative and 9 to be falsely positive (i.e.
9 of the 53 participants would have a positive test but not progress to ADD). The
small size of the included study lowered our confidence on these estimates of accuracy
and it is still possible that the test is considerably less accurate than these results
suggest. We conclude that 18 F‐florbetaben imaging is a promising test to predict
the progression from MCI to ADD; however, we need more studies to clearly demonstrate
its accuracy.