FDA’s New Final Rule on LDTs

A Paradigm Shift in the Regulation of Diagnostic Devices

In the realm of diagnostic testing, Laboratory Developed Tests (LDTs) have long occupied a unique position. Developed and performed within a single laboratory, these tests have been subject to varying degrees of regulatory oversight over the years. However, the FDA’s latest Final Rule on LDTs, issued on May 6, 2024, signifies a significant regulatory overhaul. Under this ruling, LDTs will now face premarket review akin to other diagnostic devices, emphasizing safety and efficacy. Key aspects include risk-based classification, compliance requirements, and a transition period for compliance. Proponents highlight enhanced patient safety and innovation incentives, while critics express concerns over regulatory burden and potential innovation stifling. As stakeholders adapt, collaboration and ongoing evaluation will be essential to navigate this transformative regulatory landscape and ensure continued advancement in diagnostic testing. We’ll discuss here key takeaways regarding the Final Rule and phaseout policy.

How We Got Here: The Evolution of LDT Regulation

The regulatory oversight of LDTs has been a topic of ongoing debate and evolution. Historically, LDTs have largely operated under the purview of the Clinical Laboratory Improvement Amendments (CLIA), which focuses primarily on laboratory quality standards. However, as the complexity and clinical significance of LDTs have increased, calls for more robust regulatory oversight have grown louder. The FDA’s latest Final Rule represents a response to these calls, aiming to establish a clearer regulatory framework for LDTs while balancing innovation and patient safety.

Key Components of the Final Rule

The FDA’s Final Rule makes explicit that LDTs are in vitro diagnostic devices that are (and always have been) subject to FDA regulatory oversight, and includes several key components that will shape the regulatory landscape for diagnostic testing:

  • Risk-Based Classification: Under the new framework, LDTs will be classified based on their risk profile, with higher-risk tests subject to more stringent regulatory requirements. This risk-based approach acknowledges the diverse nature of LDTs and aims to tailor regulatory oversight to the level of risk posed to patients and public health.
  • Pre-market Review and Approval: Perhaps the most significant departure from previous practices is the requirement for pre-market review and approval of certain LDTs. This represents a shift away from the historical enforcement discretion exercised by the FDA over LDTs and towards a more structured approach to regulatory oversight. By requiring pre-market review, the FDA aims to ensure the analytical and clinical validity of LDTs before they are made available for clinical use.
  • Compliance Requirements: The Final Rule establishes specific requirements for laboratories developing and offering LDTs, including validation of analytical and clinical performance, adherence to quality system regulations, and reporting of adverse events. These requirements are designed to enhance the reliability, accuracy, and safety of LDTs, thereby bolstering confidence in diagnostic results and improving patient care.

Below is a summary of the phases and timeline for compliance:

Stage 1

May 6, 2025

Labs must have procedures in place to comply with the following:

(a)   Medical Device Reporting

(b)  Corrections and Removals

(c)   Quality System requirements re: Complaint Handling

Stage 2

May 6, 2026

Labs must register their establishment (e.g. facility) with FDA and list each individual LDT

LDTs must comply with FDA labeling requirements, including general labeling requirements for medical devices and specific labeling requirements for IVDs

Labs that are conducting LDTs for clinical investigations must comply with relevant investigational device requirements

Stage 3

May 6, 2027

Compliance with the Quality System (QS) requirements in 21 CFR Part 820

Stage 4

November 6, 2027

PMA Submissions for high-risk (Class III) tests, unless otherwise exempt. Unless a premarket submission has been received by the beginning of this stage, FDA intends to exercise enforcement discretion for the pendency of its review.

Stage 5

May 6, 2028

Low and moderate-risk LDTs requiring premarket notification (510(k) notification) or de novo submission must comply with the 510(k) or de novo requirements, unless otherwise exempt. Unless a premarket submission has been received by the beginning of this stage, FDA intends to exercise enforcement discretion for the pendency of its review.

FDA has also created several categories of tests for which the Agency has advised it will exercise varying levels of enforcement discretion. Additionally, FDA clarifies that tests intended solely for forensic or law enforcement use and public health surveillance tests continue to remain subject to FDA enforcement discretion. FDA also intends to exercise enforcement discretion for currently marketed LDTs with respect to premarket review and most quality systems requirements.

Implications for Healthcare Stakeholders

The FDA’s Final Rule on LDTs has sparked a range of reactions and considerations among healthcare stakeholders.

Laboratories and test developers will need to navigate the new regulatory requirements, ensuring compliance with validation standards, quality systems, and reporting obligations. For some laboratories, particularly smaller entities with limited resources, meeting these requirements may present challenges and necessitate investments in infrastructure, expertise, and regulatory compliance.

Patients and clinicians stand to benefit from the enhanced oversight of LDTs, which may lead to improved diagnostic accuracy and patient outcomes. By ensuring the reliability and safety of LDTs, the Final Rule aims to instill greater confidence in diagnostic testing and empower clinicians to make informed treatment decisions.

While increased regulatory oversight may enhance the quality and reliability of LDTs, some stakeholders have expressed concerns about its potential impact on innovation and access. Striking the right balance between regulatory rigor and flexibility will be crucial to foster continued innovation in diagnostic testing and ensure that patients have access to cutting-edge diagnostic technologies.

Concluding Note

The FDA’s new Final Rule on Laboratory Developed Tests represents a significant milestone in the regulation of diagnostic testing, aiming to enhance patient safety, reliability, and confidence in diagnostic results. While the regulatory landscape may continue to evolve, we recommend affected laboratories and test developers understand key requirements of the Final Rule, begin to develop a gameplan for compliance, and continue monitoring FDA’s regulation and enforcement of LDTs to ensure compliance.

For more information on FDA’s regulation of LDTs and U.S. medical device compliance matters, please contact us at

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