Deficiency Writing

for Third Party Reviewers 

Ksenia Blinova, PhD

Center for Devices and Radiological Health

U.S. Food and Drug Administration
2

Benefits of Clear Communication

• Efficiently identify outstanding issues

• Clearly identify expectations

• Reduce multiple rounds of addressing the 

same issue

• Lead to faster, timely review decisions
3

1. Deficiency Writing for Third Party Reviewers

2. Examples and Knowledge Checks

How to Use this Presentation
4

• Describe guiding principles of deficiency 

writing

• Understand four-part harmony format

• Differentiate between major and minor 

deficiencies 

Learning Objectives
5

Guiding Principles of

Deficiency Writing
6

Background of Deficiency Writing

• Third Party Reviewers evaluate 510(k) submission

• Additional information may be needed to make final 

recommendation

– Requests for additional information are known as 

deficiencies

– Communicated through deficiency letters
7

Relevant Guidance Documents

• Developing and Responding to Deficiencies in Accordance with 

the Least Burdensome Provisions

www.fda.gov/regulatory-information/search-fda-guidance-documents/developing-and-responding-deficiencies-accordance-leastburdensome-provisions

• The Least Burdensome Provisions: Concept and Principles

www.fda.gov/regulatory-information/search-fda-guidance-documents/least-burdensome-provisions-concept-and-principles

• The 510(k) Program: Evaluating Substantial Equivalence in 

Premarket Notifications [510(k)]

www.fda.gov/regulatory-information/search-fda-guidance-documents/least-burdensome-provisions-concept-and-principles
8

Guiding Principles

• Only include information necessary to 

make regulatory decision

• Consider and suggest alternative 

approaches
9

• Deficiencies should request:

– minimum (that is, least burdensome) amount of 

information

• necessary to adequately address the issue

• in the most efficient manner

• at the right time 

Guiding Principles
10

Four-Part Harmony
11

Benefit of Four-Part Harmony

• Ensures understanding of request 

• Facilitates FDA review of Third Party 

recommendations

• Improves efficiency and timeliness of 510(k) 

process
12

Part 1: What Was Provided

• Identify what was provided

• Acknowledge any information the sponsor 

provided relevant to the deficiency
13

Part 2: What Is Deficient

• Explain what is deficient in submission

• Be specific about why current information is 

deficient or not adequate

• Cite references from submission
14

Part 3: Why Is It Needed

• Explain reason why information is needed

• “Why” may not be understood by audience with 

diverse backgrounds

– Scientist, Regulatory Affairs, Business

– Explicitly identifying reason helps to understand issue

• Reference applicable section of final rule, 

guidance, or FDA-recognized standard
15

Part 4: What Is Needed

• Identify what is needed

• Be succinct and specific

• Use directive statements such as:

– “Please provide”

– “Please justify”

– “Please clarify”
16

Part 4: What Is Needed

• Avoid “Shall” or “Must”

• Avoid questions, for example:

– “Why did you...?”

– “What if you...?”

• Suggest alternative ways of addressing the 

issue
17

Four-Part Harmony

1. What was provided

2. What is deficient

3. Why it is needed

4. What is needed
18

Major and Minor Deficiencies 
19

What are the Terms?

• Major Deficiency

- Will lead to a “Not Substantially Equivalent” 

recommendation if not resolved

• Minor Deficiency

- Can be resolved in a straightforward manner, 

but needs to be addressed

• Additional Considerations

- Not expected to preclude a favorable decision
20

Major Deficiencies

• Time- or resource-intense requests 

(e.g., new testing or analysis)

• Should only be included if their resolution is 

necessary for the final decision

• Written in four-part harmony
21

Minor Deficiencies

• Still need a response, but straightforward 

(e.g., labeling statements)

• Related to potential misbranding or 

adulteration

• Written in four-part harmony
22

Additional Considerations

• Is it needed for the decision?

• If no, it is an additional consideration

• No response from sponsor is needed

• They do not need to be written in four-part 

harmony
23

• Be as detailed as possible

– cite page numbers, paragraphs, sections of 

submission

• Provide context for very specific deficiencies

• Prioritize in order of significance

Tips for Good Deficiencies
24

Summary

• Clearly communicating deficiencies is key to efficiently 

completing the review of an application

• Best practices in deficiency writing incorporate least 

burdensome and four-part harmony principles

• Organize deficiencies into major, minor, and additional 

considerations sections

– and prioritize in order of significance
25

1. Apply the principles described in this 

presentation

2. View the companion CDRH Learn module 

for specific examples of deficiency writing

Your Call to Action