2.1. Decision support: cytomegalovirus assays
Tests for cytomegalovirus (CMV) include antigenemia testing, viral
load testing by quantitative polymerase chain reaction (qPCR), viral
genotyping, shell vial culture, or serologic tests for the detection of a
host immunologic response (CMV IgM and IgG antibody tests and antibody
avidity tests). For an individual patient, the most appropriate test
depends on the clinical indication. It is difficult for clinicians to keep upto-date
with esoteric tests in rapidly evolving specialties, especially
when there are numerous tests that can be ordered. In these situations,
the use of a decision support tool is an effective mechanism to assist
physicians in proper test selection, potentially avoiding inappropriate
test selection. As one example, Fig. 1 shows a screen display from the
on-line laboratory handbook at the Massachusetts General Hospital.
When the clinician types “cytomegalovirus” or “CMV” into the
handbook's search function, the available tests and their appropriate indication
are presented. In addition, the same decision-support information
is provided in the electronic physician order entry (POE) system
when a clinician views CMV-related test options. An advantageous feature
of this approach is that when new tests become available, or outdated
ones are removed from the test menu, the decision-support
function can be updated accordingly. For example, the MGH microbiology
laboratory recently discontinued the CMV antigenemia assay in
favor of the CMV qPCR test. The information provided in the on-line
handbook makes it clear that the preferred test has changed. This approach
can be applied to many other tests in microbiology, particularly
in areas such as molecular microbiology where new assays are
supplanting more traditional assays at a rapid rate. The topic of decision support is covered in more detail in another chapter of this special
edition.