|

|
Consent for testing should be obtained in a manner
consistent with that for other medical care and services
provided in the same setting, and should include measures to prevent unwanted disclosure of test results to others.
Persons should be provided with information regarding
-
exposures
associated with the transmission of HCV, including behaviors or exposures that might have
occurred infrequently or many years ago;
-
the test procedures and the meaning of
test results;
the nature of hepatitis C and chronic liver disease;
-
the benefits of detecting infection
early;
-
available medical treatment; and
-
potential adverse consequences of
testing positive, including disrupted personal relationships and
possible discriminatory action (e.g., loss of
employment, insurance, and educational
opportunities).
Comprehensive information regarding hepatitis C should
be provided before testing; however, this might not be
practical when HCV testing is performed as part of a
clinical work-up or when testing for anti-HCV is required. In these cases, persons should be informed that a) testing
for HCV infection will be performed, b) individual results
will be kept confidential, and c) appropriate counseling
and referral will be offered if results are positive.
Testing for HCV infection can be performed in various
settings, including physicians' offices, other health-care
facilities, health department clinics, and HIV or other
freestanding counseling and testing sites. Such settings should be prepared to provide appropriate information regarding hepatitis C and provide
or offer referral for additional medical care or other needed services (e.g., drug
treatment), as warranted. Facilities providing HCV testing should have access to
information regarding referral resources, including availability, accessibility, and
eligibility criteria of local medical care and mental health professionals, support
groups, and drug-treatment centers.
The diagnosis of HCV
infection can be made by detecting either anti-HCV or HCV RNA. Anti-HCV for routine
testing of asymptomatic persons should include both EIA to test for anti-HCV and
supplemental or confirmatory testing with an additional, more specific assay. (Figure
3.) Use of supplemental antibody testing (i.e., RIBA™) for all positive
anti-HCV results by EIA is preferred, particularly in settings where clinical services
are not provided directly.
|
|
|
Supplemental
anti-HCV testing confirms the presence of anti-HCV (i.e., eliminates false-positive
antibody results), which indicates past or current infection, and can be performed on
the same serum sample collected for the EIA (i.e., routine serology). Confirmation or
exclusion of HCV infection in a person with indeterminate anti-HCV supplemental test
results should be made on the basis of further laboratory testing, which might include
repeating the anti-HCV in two or more months or testing for HCV RNA and ALT level.
In clinical settings, use of RT-PCR to detect HCV RNA
might be appropriate to confirm the diagnosis of HCV
infection (e.g., in patients with abnormal ALT levels or
with indeterminate supplemental anti-HCV test results)
although RT-PCR assays are not currently FDA-approved. Detection of HCV RNA by RT-PCR in a person with an
anti-HCV-positive result indicates current infection. However, absence of HCV RNA in a person with an
anti-HCV-positive result based on EIA
testing alone
(i.e., without supplemental anti-HCV testing) cannot
differentiate between resolved infection and a false-positive anti-HCV test result. In addition, because some persons with HCV infection might
experience intermittent viremia, the
meaning of a single negative HCV RNA result is difficult
to interpret, particularly in the absence of additional
clinical information. If HCV RNA is used to confirm anti-HCV results, a separate serum sample will need to be collected and handled in a
manner suitable for RT-PCR. If the HCV RNA result is negative, supplemental
anti-HCV
testing should be performed so that the anti-HCV EIA
result can be interpreted before the result is reported to the patient.
Laboratories that perform HCV testing should follow the
recommended anti-HCV testing algorithm, which includes
use of supplemental testing. Having assurances that the
HCV testing is performed in accredited laboratories whose services adhere to recognized
standards of good laboratory practice is also necessary. Laboratories that perform HCV
RNA testing should review routinely their data regarding internal and external proficiency
testing because of great variability in accuracy of HCV RNA testing.
|