Test Complexities

At a glance

Clinical laboratory test systems are assigned a moderate or high complexity category on the basis of seven criteria given in the Clinical Laboratory Improvement Amendments of 1988 (CLIA) regulations.

Test complexity categorization

Clinical laboratory test systems are assigned a moderate or high complexity category on the basis of seven criteria given in the CLIA regulations. For commercially available FDA-cleared or approved tests, FDA scores the tests using these criteria during the pre-market approval process. The final score determines whether the test system is categorized as moderate or high complexity. Tests developed by the laboratory or that have been modified from the approved manufacturer’s instructions default to high complexity according to the CLIA regulations.1

FDA: CLIA Categorizations

CMS: Categorization of Tests.

Waived testing

As defined by CLIA, waived tests are simple tests with a low risk for an incorrect result. They include:

  • Certain tests listed in the CLIA regulations
  • Tests cleared by the FDA for home use
  • Tests that the manufacturer applies to the FDA for waived status by providing scientific data that verifies that the CLIA waiver criteria have been met

Sites that perform only waived testing must have a CLIA certificate and follow the manufacturer’s instructions; other CLIA requirements do not apply to these sites.

FDA: CLIA Waiver by Application

Keep Reading: Waived Tests

Nonwaived testing

Nonwaived testing is the term used to refer collectively to moderate and high complexity testing. Laboratories or sites that perform these tests need to have a CLIA certificate, be inspected, and must meet the CLIA quality standards.2345

Provider-performed microscopy (PPM) procedures

PPM procedures are certain moderate complexity microscopy tests commonly performed by health care providers during patient office visits. The PPM subcategory includes a limited set of microscopic evaluations listed in the CLIA regulations. They are performed on samples such as urine, skin scrapings and excretions.6

CLIA offers a PPM certification option for this limited set of moderate complexity tests. They accommodate the unique needs of health care providers in clinical settings. Only certain types of providers qualify as testing personnel for PPM tests under a PPM certificate. They include physicians, dentists and midlevel practitioners.6

Centers for Medicare & Medicaid Services: List of PPMP tests (including CPT/HCPCS codes).

Keep Reading: Provider-Performed Microscopy Procedures

Related terms

Several terms including “CLIA-exempt,” “FDA-cleared,” and “point-of-care testing” might mistakenly be confused with CLIA-waived testing. These terms do not relate directly to the test complexity categories, and it cannot be assumed that a test system is waived simply because it is performed at the point of care.

  • “CLIA-exempt” formally refers to a laboratory (not a test system) and means a laboratory that has been licensed or approved by a state where CMS has determined that the state has enacted laws relating to laboratory requirements that are equal to or more stringent than CLIA requirements, and the State licensure program has been approved by CMS.7
  • “FDA-cleared” means a test system has been reviewed by the FDA and has been determined to be substantially equivalent to a test system already legally marketed for the same use. This could apply to waived, moderate, or high complexity test systems.
  • “Point-of-care testing” is a phrase used to describe the location where testing is performed, such as at the bedside or near the site of patient care. While some point-of-care tests are approved for a CLIA waiver, advances in technology that enhance the rapidity of testing enable more complex, nonwaived testing to be performed at or near the site of patient care.

Significance of test complexity

Clinical laboratories or other testing sites need to know whether a test system is waived, moderate, or high complexity for each test on their menu because this determines the applicable CLIA requirements. In general, the more complicated the test, the more stringent the requirements under CLIA. Laboratories or sites that perform only waived tests only need to follow the manufacturer’s instructions for those tests to meet CLIA requirements.

Nonwaived testing is subject to inspection, and must meet the CLIA quality system standards, such as those for proficiency testing, quality control and assessment, and personnel requirements. The standards for moderate and high complexity testing differ only in the personnel requirements. The categories of tests a laboratory offers is also a factor in determining the appropriate CLIA certificate for the laboratory.

For a general overview of CLIA certificate types, see CMS’ Clinical Laboratory Improvement Amendments (CLIA) Brochure.

Determining test complexities for specific tests

The complexity categorization or waiver status for a test may be printed in the manufacturer’s package insert or other instructions.

The FDA and CMS websites have several resources:

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Content Source:
Division of Laboratory Systems (DLS)
  1. 42 CFR 493.17: Test Categorization
  2. 42 CFR Subpart H: Participation in Proficiency Testing for Laboratories Performing Nonwaived Testing
  3. 42 CFR Subpart J: Facility Administration for Nonwaived Testing
  4. 42 CFR Subpart K: Quality System for Nonwaived Testing
  5. 42 CFR Subpart M: Personnel for Nonwaived Testing
  6. 42 CFR 493.19: Provider-performed microscopy (PPM) procedures
  7. 42 CFR 493.2: Definitions