How Does AlloMap Work?
AlloMap® measures the levels of 20 genes in your blood. These genes have been identified as having a role in rejection. The levels of these genes are converted into an AlloMap test score. This score is reported on the AlloMap Report (shown below) and appears as an integer ranging from 0 to 40. Your transplant team uses your AlloMap test score, along with other standard tests, to assess how your immune system is behaving in the presence of your new heart. AlloMap may be used more frequently in the first year after your transplant, and may be used less frequently over time. Your transplant team can advise when AlloMap testing should be ordered for you.
1: AlloMap Test Score
The AlloMap test algorithm transforms the measured expression levels of 20 genes into an integer value ranging from 0 to 40. In the example report, the current sample has an AlloMap test score of 35 for a patient beyond 12 months.
2: 95% Confidence Interval
The 95% confidence interval (C.I.) provides a measure of score reproducibility. For example, the 95% C.I. of 34.6 to 35.3 for an AlloMap test score of 35 indicates that if the test were repeated 100 times, 95 of the test scores would be expected to fall between 34.6 and 35.3.
3: Post-Transplant Periods
The prevalence of transplant rejection is highest immediately post-transplantation and decreases through the first post-transplant year. For the convenience of the clinician who is reading and interpreting the test results, the time post-transplant that corresponds to the most recent AlloMap score appears above the graph.
4: Negative Predictive Value (NPV)
Each test score is associated with an NPV that is the probability that the patient does not have current rejection. For example, an AlloMap test score of 35 is associated with an NPV of 98.7% that indicates a 98.7% estimated probability that the patient is not experiencing current rejection.
5: Positive Predictive Value (PPV)
Similarly, each test score is associated with a PPV, which is the probability that the patient does have acute cellular rejection (ACR) at the time of testing. The AlloMap test has a comparatively low PPV (relative to its NPV), and therefore, an AlloMap test score should not be used to “rule in” ACR.