Hepatitis C is an active inflammation of the liver that can become a chronic infection if left untreated. This condition can be diagnosed easily using simple blood tests.
While testing for hepatitis C is fairly simple, it is not always accurate. The antibody testing for hepatitis C relies heavily on developing antibodies in the blood. The antibody test is, thus, heavily reliant on a variable factor and not always reliable. While the antibody test is fairly accurate in determining when a person does not have hepatitis C, it is not always accurate when trying to weed out the true positive cases. Therefore, the anti-HCV antibody test can give false-positive results for many patients.
Although the anti-HCV antibody test is not 100% accurate, it is still the preferred initial testing modality whenever a diagnosis of hepatitis C is suspected. This is because the results can be made considerably reliable by simply repeating the test one additional time.
HOW ACCURATE IS THE ANTIBODY TESTING FOR HEPATITIS C?
The antibody testing for hepatitis C is the investigation of choice whenever a diagnosis of hepatitis C is suspected. However, this test is not 100% accurate. Why is the antibody test still preferred even when it does not yield 100% correct results? We might have to learn more about how the test works before answering that question.
The antibody testing for hepatitis C works by detecting antibodies against the hepatitis C virus in a patient’s blood. These antibodies are formed whenever a person’s blood is infected with the hepatitis C virus. Thus, a measure of the antibody response provides an indirect measure of a person’s hepatitis C status.
Since the antibody test for hepatitis C measures an indirect parameter in the blood test for hepatitis C, it is prone to slight errors here and there. Moreover, the test is also heavily reliant on the formation of antibodies and is, therefore, affected by the window period as well.
The window period for any disease is the time it takes for seroconversion to occur since the time of initial exposure. The window period for hepatitis C is 4-10 weeks. This means that, in theory, the anti-HCV antibody test should only provide valid results at least after ten weeks of initial exposure.
Now that you understand the basic mechanism of how the antibody test for hepatitis C works and how it is affected by various parameters, it is not hard to see how it can't be accurate 100% of the time.
The accuracy of a test is defined by two distinct parameters: the test's specificity and the test sensitivity. The specificity of a test is how capable a test is in figuring out who does not have a certain disease. In simple words, the specificity of a test is its ability to weed out true negative test results.
The sensitivity of a test, on the other hand, is the test's ability to figure out which patients have the disease, meaning the ability of the test to figure out the true positives. The anti-HCV antibody test is fairly specific, but the test's sensitivity is slightly problematic. This means that antibody test for hepatitis C is not always good at figuring out which patients absolutely have the disease. Thus, sometimes it gives out false-positive test results.
According to this lab review, the specificity of the anti-HCV antibody test was somewhere between 97-and 99%. However, the sensitivity of the same test lay somewhere around 61-81%.
WHICH TEST IS 100% ACCURATE FOR HEPATITIS C TESTING?
While no test is 100% accurate in diagnosing a certain disease, some tests perform better than others. This is true for the HCV RNA testing kit for hepatitis C as well.
The HCV RNA test quantifies a much more direct measure in a person’s blood: the viral RNA. Viral RNA in a person’s blood is a direct indicator of the presence of the hepatitis C virus. Therefore, the HCV RNA test is much more accurate in diagnosing hepatitis C than the anti-HCV antibody test.
However, even the HCV RNA test is not free of false results. The test is overly sensitive and sometimes returns false-positive results for no good reason. Therefore, like the antibody test, the HCV RNA test needs to be repeated as well to reach a concrete conclusion.
WHAT TO DO WHEN YOU TEST POSITIVE FOR HEPATITIS C?
Testing positive for hepatitis C can be stressful. The inflammation can be problematic, especially if it turns chronic. Sometimes, patients are left with lifelong liver damage that can only be fixed by a liver transplant. However, the diagnosis is not as scary as it once used to be. Modern medications have made it possible to treat and completely cure a person suffering from hepatitis C. However, there are a few things you need to understand when you test positive for hepatitis C.
First of all, a single positive hepatitis C test result does not mean that you have hepatitis C. As we have seen so far, hepatitis C testing is prone to returning false-positive results. Therefore, doctors employ a multi-stage testing algorithm to eliminate the possibility of a false test result. Your single positive test result will need to be repeated and supplemented with another testing modality to confirm the positive.
Secondly, a diagnosis of hepatitis C is not the end of the world. While hepatitis C once used to be a fatal liver inflammation, it is now a very treatable and even curable disease. Modern Direct Acting Antivirals, or DAAs, can effectively eliminate the hepatitis C virus from the blood in 8-12 weeks.
Once you test positive for hepatitis C, your doctor will evaluate other parameters, including the health of your liver. These parameters will determine whether you need treatment with DAAs for your acute episode or not.