Diagnostic Tests for Alzheimer's Disease: Rationale, Methodology, and Challenges
Table 1
Advantages and disadvantages of different approaches to developing an accurate diagnostic test.
Advantages
Disadvantages
Single test
Fast and often easy to perform. Acceptable to the patient Often inexpensive Reproducible and quantitative
The Diagnostic Odds Ratio (DOR) may not be clinically significant with only one test in such a complex disorder Results may only be significant in a highly defined population where pre-test probability is already high
Multiple tests
More tests should each add incremental benefit to the constituent single tests and increase DOR accordingly Can combine tests from different domains, for example genetic, clinical, radiological, and proteomic
Patient must undergo many tests to complete the battery Much research is required before these batteries are available May be expensive when including specific assays and imaging Results may only be significant in a defined population where pretest probability already high
Consensus
Such criteria are easy to produce as do not rely on any systematic, unbiased and comprehensive literature review or testing. Such criteria have already been described [8, 9]
While these criteria are produced and highlight the need for validation, they are often accepted as being valid before this process is undertaken or completed They tend to represent a series of well educated, best guesses. Diagnostic criteria then need testing but application of consensus criteria tends to be piecemeal due to multiple “either/or” criteria. Lack the rigour of well defined tests with thresholds and inherent objectivity Most require many tests and time from clinical and radiological specialists which may make it hard to reproduce between centres Resources required are expensive. The need for further verification of current criteria have been highlighted [8, 9]
