In 2003, FDA issued an updated guidance on the "Replacement Reagent and Instrument Family Policy" for in vitro diagnostic (IVD) devices. The 2003 guidance described a mechanism for manufacturers to follow when applying an assay that was previously cleared based on performance characteristics when used with a specified instrument to an additional instrument that is either cleared or a member of an instrument family from which another instrument was previously cleared. Through the approach described in the 2003 guidance, manufacturers established sufficient control to maintain the level of safety and effectiveness demonstrated for the cleared device for these types of modified devices, when evaluated against predefined acceptance criteria using a proper validation protocol, without submission of a premarket notification (510(k)).

For consistency of terminology with previous guidances and FDA-manufacturer communications, this updated guidance continues to use the terms "Replacement Reagent" and "Instrument Family Policy." Within discussions in this guidance, generally the term "assay" is used instead of the term "reagent" to better represent typical scenarios, because most assays are currently comprised of multiple reagents.

FDA believes this guidance is important for public health as FDA continues to promote more timely availability of a wider array of clinical laboratory tests for patient benefit. This guidance is intended to update and provide clarity on the Replacement Reagent and Instrument Family Policy for manufacturers of IVD devices and FDA staff to promote consistent application of the concepts in this guidance. This guidance also incorporates concepts and recommendations from FDA's guidances entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device," "Deciding When to Submit a 510(k) for a Software Change to an Existing Device," and "The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications [510(k)]," and includes recommendations and information specifically regarding:

• Manufacturer's preliminary considerations for determining whether this guidance is applicable (Section II)
• The Replacement Reagent Policy (Section III)
• The Instrument Family Policy (Section IV)
• Examples (Section V)
• Labeling (Section VI)
• Clinical Laboratory Improvement Amendments (CLIA) categorization when the manufacturer determines, taking into account the considerations described in this guidance, that a 510(k) is not needed (Section VII)

In addition, the guidance includes two Appendices. Please refer to Appendix 1: Significant Terminology for the meaning of key terms used in this guidance. Please refer to Appendix 2: Flowchart Aids for a series of flowcharts that are intended to supplement this guidance, but are not intended to be used alone. The flowcharts are provided as a visual aid only and are not intended to capture all appropriate considerations in determining whether the policies in this guidance may be applicable for your proposed modifications to certain IVD devices. Refer to the corresponding text of this guidance when using the flowcharts.