Would You Like To Be Statistically Diagnosed?

The above title may sound funny but with theeliminate some of the need for traditional,
advent of microarray technology it is entirely possibledoctor-enabled pattern recognition. I do not think,
for your doctor to ask you a question like this.however, that the pattern-recognition capacity of
Namely, any array-based diagnostic test thatmicroarrays is anywhere near to do so because (1)
determines a multi-component disease signature istechnical standards for diagnostic microarrays do not
inherently generating a statistical statement. Forexist, (2) the mathematics of pattern-recognition
example:makes sense to statisticians but not doctors and
The test results demonstrate with 90% confidencepatients, and most importantly, (3) the medical
that your chances to have Disease X are 75% ascommunity does not have surrogate biomarkers,
detected by the marker-pattern, which is up to 85%except for infectious disease. In short, in addition to
sensitive and specific to Disease X.great potential, the microarray technology brings
The above statement may sound unintelligible andunique challenges for scientists, IVD industry, medical
make no medical sense but if you compare thecommunity, and the regulatory institutions. Some of
process behind this hypothetical machine-generatedthese challenges are formulated in DIAGNOSTIC
statement to traditional clinical diagnostics, then youNUCLEIC ACID MICROARRAYS [MM12A, 2006;
realize the similarity. Namely, both are actually patternClinical and Laboratory Standards Institute (CLSI)].
recognition. Traditionally, diagnostics has been enabledAnd I would like to point here to my favored one:
by doctors' experience so that the more experiencedQUALITY MANAGEMENT OF THE PRODUCTION
the doctor, the better his of her ability to recognizeAND PERFORMANCE OF DIAGNOSTIC
symptoms and synthesize these symptoms into aMICROARRAYS.
disease-pattern, a.k.a. as DIAGNOSIS. Except forImagine the amount of quality control and quality
simple cases, doctors do pattern-recognition routinely.assurance (QC/QA) you need for a 10-element array
For example, you go to your doctor with complaintsas opposed to a traditional ELISA test that
including chronic fatigue, occasional fever, head-ache,determines only a single marker. Remember that one
shortness of breath, and loss of appetite. Yourhas to be able to QC/QA all of the array elements.
doctor listens to you, looks at you, and analyzesThe best way do so is to design a statistical QC/QA
your chest X-rays, blood-test etc. Depending onmethodology, and cut back on the number of array
what your doctor finds, you might either have someelements as much as possible. In summary, despite
pulmonary ailment or no detectable disease at all.great promise, diagnostic arrays will have to
How do doctors come up with these diagnoses?overcome formidable technical challenges. And before
Very simply, they analyze patterns, which can greatlythey enter routine clinical practice, the diagnostic
overlap from disease to disease but also containarrays that produce multi-component diagnostic
specific components that determine the diagnosis andsignatures will have to prove that they make clinical
therapy.diagnostics more accurate and cost-effective. Unless
At some point in the future, the era of diagnosticthey become capable of detecting surrogate
microarrays will arrive, and the clinical patternbiomarkers, which for most diseases are yet to be
recognition is enabled by tiny chips, which quantifydiscovered, or provide useful information as to the
molecular disease markers instead of talking to you,best therapy for a patient, we will only be seeing
looking at you, listening to you, and analyzing yourexperimental tests along with statistical diagnostics
X-rays(see above). So, would you like to be statistically
Thus, the future diagnostic microarrays will potentiallydiagnosed?