Biomedical Engineering Reference
In-Depth Information
Table 2.1
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Continued
)
Information to be provided about the design of the sensitivity and
specificity studies that were performed should include characteristics
of the samples and positive and negative controls, the rationale for
interfering substances studied, analyte or entity (e.g., tumor cells
harboring a particular mutation) spike-in amounts and matrices
used in any dilution experiments. Summary results such as sensitivity
and specificity rates over the range of test samples considered, and
calibration or dilution curves should be presented, as appropriate.
E. Accuracy measurements
Accuracy is defined as the closeness of agreement between the test
results obtained using the new biomarker test and results obtained
using a reference standard method widely accepted as producing
“truth” for the analyte. For example, a reference method considered
standard for detection of DNA mutations is sequencing. The observed
level of agreement will depend on both the bias and precision of the
new test. Bias is the amount by which an average of many repeated
measurements made using the new test systematically over- or
underestimates the reference standard method result. Precision is
discussed separately above. For many new biomarker tests, there will
not be a universally accepted reference standard method.
The reference standard method, if any exists, should be clearly stated.
Accuracy measures such as overall percent agreement, and sensitivity
and specificity relative to the reference standard results should be
reported for tests that yield binary results. For continuous marker
values, accuracy measures such as average bias, mean absolute
deviation or mean squared deviation should be reported over the
relevant range of true (reference standard method) values.
In addition to the information indicated above, the general background
and description of the biomarker-based test should include:
F. Statement indicating whether the test is quantitative (includes degrees
of positivity), semi-quantitative, or qualitative (positive vs. negative);
what platform will be used; what is to be measured; controls; scoring
procedures, including the values that will be used (e.g., pos vs. neg;
1+, 2+ 3+); interpretation, etc. If the biomarker-based test combines
values for multiple biomarkers into a composite score, then the exact
algorithm for combining the values must be specified, including any
cutpoints applied to the composite score.
