In addition to FDA approval, all commercial tests must be evaluated by individual laboratories before they are put into use. A lab must demonstrate that it can perform the test with the same accuracy and precision as specified by the manufacturer of the test. And commercial tests, once they have been put into practice, must be evaluated on a regular basis with in-house quality assurance programs to ensure that performance of these tests continues to meet specifications. As is true for any laboratory test, ongoing assessments of commercial tests by the laboratory using the test are regulated by the Clinical Laboratory Improvement Amendments (CLIA). This topic is discussed further in the article Lab Oversight: A Building Block of Trust.
Complexities of commercial tests
Once approved, FDA assigns complexity to a test, grouping it into one of three categories as specified by CLIA regulations: waived, moderate and high complexity.
- Waived tests are simple, easy to use, and have low risk for incorrect results. Some of these tests are even available over the counter. Common examples of waived tests include pregnancy, fecal occult blood tests, and some types of urine tests.
- Moderate complexity tests are not as simple or easy to use as waived tests. They require some degree of personnel education, training, and experience. This category includes the Provider-Performed Microscopy Procedures (PPMP) subcategory in which healthcare providers may perform some of the tests. Complete blood count, automated immunoassays, urinalysis or urine drug screens, and electrolyte or chemistry profiles are common examples of moderate complexity tests.
- High complexity tests require specialized laboratory expertise and may include molecular diagnostic tests, cultures or molecular tests that identify causes of infections (e.g., bacteria, viruses), cytology, immunohistochemistry, flow cytometry, blood smears, or gel electrophoresis. All laboratory-developed tests (LDTs) are classified as high complexity tests. (Read the section of this article on Laboratory-developed Tests.)
For moderate and high complexity tests, FDA employs the use of a "scorecard" to determine the level of complexity. The scorecard includes seven categories:
- Training and experience
- Materials and reagents preparation
- Characteristics of operational steps
- Calibration, quality control, and proficiency testing materials
- Test system troubleshooting and equipment maintenance
- Interpretation and judgment
FDA applies the scores of 1, 2 and 3 to each of these criteria, and any score above 12 classifies a test as high complexity. A score of 12 or below classifies a test as moderate complexity.
The Clinical Laboratory Improvement Amendments (CLIA), which require the federal government to certify non-research laboratory testing, call for stricter quality standards for tests with higher degrees of complexity.
Laboratories that enroll in the CLIA program can apply for different types of certificates to conduct different types of commercial tests:
- Certificate of Registration: this is a certificate issued for any laboratory that intends to perform non-waived (moderate and high complexity) tests to allow them to do testing while applying for a certificate of either compliance or accreditation.
- Certificate of Waiver (CW): allows labs to conduct waived tests.
- Certificate of Provider-Performed Microscopy Procedures (PPMP): offered to laboratory personnel such as doctors or dentists who do either waived tests or microscopic evaluations of samples that may include skin scrapings, urine or other types of body fluids. These tests are moderate complexity.
- Certificate of Compliance (COC) and Certificate of Accreditation (COA): labs that meet all relevant CLIA mandates are eligible for a COC. Those who conduct moderate or higher complexity tests must undergo a survey process once every two years to ensure the lab is complying with regulations and with CLIA. Labs can receive a COA if they meet federally approved standards of a private non-profit accreditation organization.
In the event a lab has any of the above certifications, it can also perform waived tests.
Additionally, proficiency testing (PT) is specifically required by CLIA regulations for some tests that are moderate or high complexity. To ensure that labs are conducting these tests accurately and competently, a lab must enroll in a PT program with a CMS-approved PT provider. The PT provider will send them several unknown samples throughout the year. The labs will perform the testing and return their results to the PT provider. The PT provider then grades each lab on how accurately their results were. For moderate or high complexity tests that do not have commercial PT available, the laboratory must perform its own evaluation of accuracy and competency in performing the test at least twice a year.
Continue to the next article in the series: Part III: Laboratory-developed Tests (LDTs)