84
An example of drug with recommendation for companion diagnosis in label
information that lists genetic susceptibility relating to effi cacy or dose is warfarin;
labeling now includes FDA-recommended genotyping for mutations in two genes
that cause increased susceptibility to bleeding, but the tests are not obligatory.
Companion diagnostics for anticancer drugs are described in the chapter on cancer.
Point-of-Care Diagnosis
Point of care (POC) or near patient testing involves analytical patient testing activi-
ties provided within the healthcare system, but performed outside the physical facil-
ities of the clinical laboratories. POC does not require permanent dedicated space,
but instead includes kits and instruments, which are either hand carried or trans-
ported to the vicinity of the patient for immediate testing at that site. Sites where
POC may be performed include doctor’s offi ce, bed side in case of hospitalized
patients, the emergency room or a disaster or war zone. POC may be performed in
the fi eld for several other indications including screening of populations for genetic
disorders and cancer. The patients may even conduct the tests themselves at home.
The most important application of molecular diagnostics is estimated to be at the
POC and rapid results are required. POC diagnosis is important for the development
of personalized medicine and various applications are listed in Table 2.7.
There are many reasons for the substantial growth of POC testing, but perhaps
the most signifi cant is that the accuracy and reliability of POC tests now approaches
that of high-volume analyzers used in clinical laboratories. For physicians, the ben-
efi t of being able to obtain test results quickly at the bedside or in a critical care
setting often outweighs the somewhat higher cost per test associated with POC test-
ing. This is particularly true in the coronary care units of hospital emergency depart-
ments, where new cardiac biomarker tests can provide rapid results that physicians
can use to make critical patient management decisions. The demand for POC tests
has also stimulated an increase in their diversity. A small variety of home tests such
as ovulation predictors, pregnancy tests, fecal occult blood assays, and blood glu-
cose monitors have been available for years. More recently, the FDA has approved
home-use tests for monitoring bladder cancer, anticoagulation therapy, urinary tract
infections, HIV status, drugs of abuse, and even risk assessment for preterm labor
and delivery.
POC diagnosis is well known with simple biochemical tests such as blood glu-
cose monitoring. Hand-held diagnostic devices, biochips and electrochemical
devices for the detection of DNA are particularly suited for POC diagnostics. Protein
biochips, particularly microfl uidic immunoassays, appear to be likely to get to POC
fi rst as several technical problems associated with use of nucleic acid biochips out-
side the laboratory are being worked out. Biochip and microfl uidic technologies are
also used for miniaturizing other laboratory tests such as cell count and automated
immunoassays. Continued improvements in biosensor technology and miniaturiza-
tion will increase the ability to test for many analytes at POC. Nanobiotechnology
2 Molecular Diagnostics in Personalized Medicine