Did some searching and the best qualitative PCR or TMA tests can detect down to 2 to 5 IU/mL compared to 12 to 15 IU/mL for the typical best quantitative tests. They also can require shipping frozen samples on dry ice like the QuantaSUREŽ HCV test.
However I wonder if the qualitative tests are really necessary with the newer DAA's like Epclusa or Vosevi. I will bring the subject up next time I talk to my liver specialist.
Canuck said
May 14, 2017
Hmm, while were are on the topic of testing ...
Hepatitis C virus core antigen assay: an alternative method for hepatitis C diagnosis.
Ann Clin Biochem. 2017; 54(2):279-285 (ISSN: 1758-1001)
Wang L; Lv H; Zhang G
Background: The study aimed to evaluate a fully automated chemiluminescent immunoassay and compared it with a quantitative RNA assay and anti-HCV assay to verify the utility of this automated Ag assay as an alternative method for hepatitis C diagnosis.
Methods: A total of 229 serum samples previously tested for anti-HCV concentrations by the Architect Anti-HCV assay, were selected for HCV RNA testing by real time RT-PCR kit (Shanghai ZJ Bio-Tec Co., Ltd) and 125 specimens were tested for HCV Ag by the Architect HCV core Antigen kit.
Results: The log10 HCVAg and HCV RNA concentrations were highly correlated [r=0.834); with HCV RNA as the comparator test, HCVAg had 100% specificity, 100% positive predictive value (PPV) and 94.8% sensitivity. We found 1 pg/mL of total HCV core Ag is equivalent to approximately 6607HCV RNA international units (IU)/mL. Receiver operator characteristic curve analysis showed that the area under the curve of HCV core Ag (0.989) was greater than HCV Ab (0.871). HCV Ag concentrations and RNA-to-Ag ratio of the groups for HCV RNA concentrations <105 and >105 IU/mL were both significantly different from each other (P < 0.05).
Conclusion: The Architect HCV core Ag assay may be an alternative method for hepatitis C diagnosis, performed on the same analytical platform and sample as the anti-HCV assay, shortening the diagnostic window period, demonstrating good correlation with HCV RNA assay with high specificity and positive predictive value.
-- Edited by Canuck on Sunday 14th of May 2017 06:40:27 AM
wendyo said
Apr 20, 2017
Thank you Canuck that was much needed.
Canuck said
Apr 20, 2017
From 2010, but I thought this lady explained the differences well ... however, I believe the lower levels of quantitative detection is currently down to about 12 or 15 IU/L, depending on country/equipment used.
How to Better Understand Your HCV Viral Load Tests - Nicole Cutler L.Ac. July 22, 2010
Although they have very similar sounding names, learn why qualitative Hepatitis C tests and quantitative Hepatitis C tests have some important differences.
To everyone except physicians who treat hepatitis and fastidious researchers, the range of tests that someone with the Hepatitis C virus (HCV) endures can be dizzying. Unless you are lucky enough to have a hepatologist sit down and explain the differences and implications of each blood draw, it is easy to be misled by the barrage of lab test results. Especially important for individuals who are currently enrolled in or who have finished HCV antiviral therapy, understanding viral load tests can bring clarification to an otherwise confusing lab result.
Hepatitis C RNA tests are tools clinicians use to confirm a diagnosis and guide treatment. The challenge in discerning between the kinds of HCV tests likely lies in the similar sounding words to describe the tests: qualitative and quantitative. Even the most seasoned healthcare practitioners frequently flub these categories. Below you will find a brief description of the two HCV RNA (the genetic material for Hepatitis C) tests and a helpful mnemonic technique to differentiate between the two:
Qualitative Test - This kind of test detects the presence or absence of HCV RNA. It is reported as either detected (positive) or not detected (negative). The qualitative test is useful to confirm an active HCV infection. The L in qualitative can be equated to a label - as in it is used to label someone as having or not having the virus.
Quantitative Test - The quantitative test measures the actual number of copies of HCV RNA in the blood. Commonly referred to as the viral load, a quantitative test is typically used to monitor how a person is responding to HCV treatment. The N in quantitative can be equated to a number - as in it is used to report the number of HCV viral particles present.
More About Qualitative Testing
To report whether or not HCV is present in the blood, the qualitative HCV RNA tests use either a process called polymerase chain reaction (PCR) or a process called transcription-mediated amplification (TMA). If such a test is positive, or detected, then chronic Hepatitis C infection is confirmed. Although it does not compute a number, the qualitative test is more accurate than the quantitative test because it can detect very low levels of the virus.
More About Quantitative Testing
Quantitative tests that measure the actual level of Hepatitis C virus in the blood may use the processes of PCR, TMA or signal amplification (branched DNA). These viral load tests compute the number of HCV RNA particles present, and are expressed in either international units per liter (IU/L) or copies per milliliter (mL). The quantitative HCV RNA test is used to monitor individuals who undergo antiviral treatment - prior to beginning therapy, during therapy and upon its completion.
Additional Viral Load Test Facts
The following seven facts about Hepatitis C viral load tests help deepen our understanding of the testing process.
If someone has a positive qualitative test but a quantitative test showing no detectable virus, then that person has a very low level of the virus in his or her blood.
If someone has a negative qualitative test following antiviral treatment, they are clear of the Hepatitis C virus.
In order to obtain a sustained viral response (considered a successful conclusion to HCV treatment), a qualitative test should be negative following the completion of treatment and then again six months later. Most physicians will use a qualitative test (as opposed to a quantitative test) to confirm a sustained viral response.
Viral load as measured by a quantitative test does not correlate with the severity of Hepatitis C.
The viral load measurement does not correlate with the severity of liver disease. Only a liver biopsy (or equivalent method) can determine the health of the liver.
Because HCV viral load will normally fluctuate, repeated viral load tests are only indicated for those on or considering antiviral treatment.
If a quantitative HCV RNA result is reported as <615 IU/L, then the test is unable to measure any of the virus. Thus, such a result should be followed by a qualitative test.
Upon reviewing the differences between quantitative and qualitative Hepatitis C tests, there will be a little less mystery in deciphering lab results. Although HCV RNA quantitative tests are mostly used to gauge how someone progresses with antiviral therapy, the qualitative test is the only way to know for sure if the Hepatitis C virus is still taking up residence in your body.
Did some searching and the best qualitative PCR or TMA tests can detect down to 2 to 5 IU/mL compared to 12 to 15 IU/mL for the typical best quantitative tests. They also can require shipping frozen samples on dry ice like the QuantaSUREŽ HCV test.
However I wonder if the qualitative tests are really necessary with the newer DAA's like Epclusa or Vosevi. I will bring the subject up next time I talk to my liver specialist.
Hmm, while were are on the topic of testing ...
Hepatitis C virus core antigen assay: an alternative method for hepatitis C diagnosis.
Ann Clin Biochem. 2017; 54(2):279-285 (ISSN: 1758-1001)
Wang L; Lv H; Zhang G
Background: The study aimed to evaluate a fully automated chemiluminescent immunoassay and compared it with a quantitative RNA assay and anti-HCV assay to verify the utility of this automated Ag assay as an alternative method for hepatitis C diagnosis.
Methods: A total of 229 serum samples previously tested for anti-HCV concentrations by the Architect Anti-HCV assay, were selected for HCV RNA testing by real time RT-PCR kit (Shanghai ZJ Bio-Tec Co., Ltd) and 125 specimens were tested for HCV Ag by the Architect HCV core Antigen kit.
Results: The log10 HCVAg and HCV RNA concentrations were highly correlated [r=0.834); with HCV RNA as the comparator test, HCVAg had 100% specificity, 100% positive predictive value (PPV) and 94.8% sensitivity. We found 1 pg/mL of total HCV core Ag is equivalent to approximately 6607HCV RNA international units (IU)/mL. Receiver operator characteristic curve analysis showed that the area under the curve of HCV core Ag (0.989) was greater than HCV Ab (0.871). HCV Ag concentrations and RNA-to-Ag ratio of the groups for HCV RNA concentrations <105 and >105 IU/mL were both significantly different from each other (P < 0.05).
Conclusion: The Architect HCV core Ag assay may be an alternative method for hepatitis C diagnosis, performed on the same analytical platform and sample as the anti-HCV assay, shortening the diagnostic window period, demonstrating good correlation with HCV RNA assay with high specificity and positive predictive value.
-- Edited by Canuck on Sunday 14th of May 2017 06:40:27 AM
Thank you Canuck that was much needed.
From 2010, but I thought this lady explained the differences well ... however, I believe the lower levels of quantitative detection is currently down to about 12 or 15 IU/L, depending on country/equipment used.
How to Better Understand Your HCV Viral Load Tests - Nicole Cutler L.Ac. July 22, 2010
Although they have very similar sounding names, learn why qualitative Hepatitis C tests and quantitative Hepatitis C tests have some important differences.
To everyone except physicians who treat hepatitis and fastidious researchers, the range of tests that someone with the Hepatitis C virus (HCV) endures can be dizzying. Unless you are lucky enough to have a hepatologist sit down and explain the differences and implications of each blood draw, it is easy to be misled by the barrage of lab test results. Especially important for individuals who are currently enrolled in or who have finished HCV antiviral therapy, understanding viral load tests can bring clarification to an otherwise confusing lab result.
Hepatitis C RNA tests are tools clinicians use to confirm a diagnosis and guide treatment. The challenge in discerning between the kinds of HCV tests likely lies in the similar sounding words to describe the tests: qualitative and quantitative. Even the most seasoned healthcare practitioners frequently flub these categories. Below you will find a brief description of the two HCV RNA (the genetic material for Hepatitis C) tests and a helpful mnemonic technique to differentiate between the two:
More About Qualitative Testing
To report whether or not HCV is present in the blood, the qualitative HCV RNA tests use either a process called polymerase chain reaction (PCR) or a process called transcription-mediated amplification (TMA). If such a test is positive, or detected, then chronic Hepatitis C infection is confirmed. Although it does not compute a number, the qualitative test is more accurate than the quantitative test because it can detect very low levels of the virus.
More About Quantitative Testing
Quantitative tests that measure the actual level of Hepatitis C virus in the blood may use the processes of PCR, TMA or signal amplification (branched DNA). These viral load tests compute the number of HCV RNA particles present, and are expressed in either international units per liter (IU/L) or copies per milliliter (mL). The quantitative HCV RNA test is used to monitor individuals who undergo antiviral treatment - prior to beginning therapy, during therapy and upon its completion.
Additional Viral Load Test Facts
The following seven facts about Hepatitis C viral load tests help deepen our understanding of the testing process.
Upon reviewing the differences between quantitative and qualitative Hepatitis C tests, there will be a little less mystery in deciphering lab results. Although HCV RNA quantitative tests are mostly used to gauge how someone progresses with antiviral therapy, the qualitative test is the only way to know for sure if the Hepatitis C virus is still taking up residence in your body.