Test Reliability
What is sensitivity and specificity?
The performance of medical tests can be measured in several different ways, and sensitivity and specificity are two of them. These terms describe how accurately a test can detect a condition or confirm its absence.
In simple terms:
- A test with 100% sensitivity would correctly identify every person who actually has the condition.
- A test with 100% specificity would never produce a false positive.
Tests that have both 100% sensitivity and specificity are actually few and far between. Most diagnostic tests do not have 100% sensitivity and specificity, including tests performed in a hospital or clinic. This means that there is always a small chance that a test may produce an incorrect result. However, Homed-IQ endeavours to select tests that have high sensitivity and specificity, similar or equal in quality to tests used in clinical settings.
What is Sensitivity?
Sensitivity describes how well a test can detect a condition when it is actually present.
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A highly sensitive test correctly identifies most people who do have the condition (few false negatives).
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In practical terms: if the test is negative, you can be confident you likely do not have the condition being tested for.
What is Specificity?
Specificity describes how well a test can confirm the absence of a condition when it is not present.
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A highly specific test correctly identifies most people who do not have the condition (few false positives).
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In practical terms: if the test is positive, it is very likely to be a true result rather than a mistaken one.
What is the sensitivity and specificity of Homed-IQ tests?
Sensitivity and specificity can only be calculated for tests that diagnose a disease or condition- such as an sexually transmitted infection (STI). These metrics cannot be calculated for tests that measure levels of substances in the blood, like vitamin D or cholesterol. This is because these markers don’t diagnose a disease directly, and there is no single universal threshold that separates “disease” from “no disease.” Instead, the values are used to assess risk or nutritional status, rather than to confirm or rule out a specific condition. However, all Homed-IQ tests are validated to be comparable in quality with tests collected in a clinical setting.
The sensitivity and specificity of Homed-IQ's STI tests are as follows:
| Marker | Sensitivity | Specificity |
|---|---|---|
| Chlamydia | 98.2% | 99.8% |
| Gonorrhoea | 97.7% | 99.8% |
| Mycoplasma Genitalium | 95.8% | 98.9% |
| Syphilis | 100% | 99.88% |
| Hepatitis B | 99.9% | 99.9% |
| HIV | 100% | 99.90% |