Molecular Diagnostics - Part 5: Analytical Sensitivity and Analytical Specificity Best Practices
The final article in our series about molecular diagnostics looks at best practices for analytical sensitivity and analytical specificity. Both are additional characteristics for laboratory-developed tests and modified FDA-cleared or approved tests.
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Molecular Diagnostics - Part 4: Reportable Range and Reference Interval Best Practices
Our series on molecular diagnostics continues with a look at best practices for two performance characteristics – reportable range and reference interval. These two characteristics need to be verified and documented for FDA-cleared or FDA-approved tests, laboratory-developed tests, and modified FDA-cleared or approved tests.
We continue our series on molecular diagnostics. Previous articles covered: what you need to verify your molecular assay and the three major components of the verification process. FDA-cleared or FDA-approved tests have four performance characteristics that must be verified and documented: accuracy, precision, reportable range, and reference interval. Laboratory-developed tests and modified FDA-cleared or approved tests have two additional characteristics for verification (analytical sensitivity and analytical specificity). Now, it’s time to turn our attention to best practices for each of the performance characteristics. First up – accuracy and precision.
3 Important Stages of Assay Verification Molecular diagnostic tests are widely available in clinical microbiology laboratories now. It’s important to a lab’s success to understand the requirements before adding a new test. Protocols aren’t specified by regulators, so they vary by lab. The assay influences the controls and parameters, but the type of verification and its complexity are determined by lab directors. In a recent article, we took a look at what to verify. This is the first of several articles that will cover how to confirm a molecular assay performs as expected.
Qualitative tests produce binary results, usually positive or negative. This presents a challenge for serological testing, since most of it is qualitative. Positive or negative results are determined in relation to a threshold value or cutoff. This cutoff, the line between positive and negative, is the medical decision point. It’s critical that this point is consistently acc urate at the lower limits of detection, where positive becomes negative. Without precision at the lower levels of positive results, laboratories may not feel confident in the results they present. Do they have a higher number of false positives or false negatives than they should?
Adding a new molecular test to your lab? Make sure you understand the regulations that apply and the required performance characteristics. The following is the first in a series of articles on this topic that will include best practices. Before we dive into the how of verification for molecular diagnostic assays, let’s take a look at the what. Clinical laboratories performing an FDA-cleared or FDA-approved test must verify that the manufacturer’s performance characteristics can be met or exceeded Laboratories performing laboratory-developed tests (LDTs) and modified FDA-cleared or approved tests, must verify the same characteristics, plus determine analytical sensitivity and analytical specificity