PPI is a coding system for questionnaires and self-completed surveys, that is provided by the All of Us Research Program.

All PPI concepts and hierarchical relationships are obtained from the All of Us PPI Codebook and its electronic successors. There are two versions of representation in the OMOP vocabulary where in the older version previously created surveys have precoordinated question-answer pairs and in the newer version, questions and answer were represented separately and answers can be reused within one survey (as in there is only one "yes" answer per survey).

PPI Questionnaires structure consists of Modules, Topics, Questions and Answers.

PPI source type value	Description
Module	A superior PPI entity representing a thematic set of topics, questions, and answers. Currently, the following Modules are available: 1) Consent PII 2) Refresher Consent 3) EHR Consent PII 4) Family History 5) Personal Medical History 6) Healthcare Access & Utilization 7) Lifestyle 8) Overall Health 9) The Basics 10) PMI 11) GROR Survey 12) Primary Consent Update 13) Sharing Your Electronic Health Records 14)COVID-19 Participant Experience (COPE) > from here on new model 15) Mental Health and Well-Being Module 16) Summer 2021 Minute Survey on COVID-19 Vaccines 17) Fall 2021 Minute Survey on COVID-19 Vaccines 18) Behavioral Health and Personality 19) Emotional Health History and Well-Being
Topic	A semantic module section containing a thematic set of questions or answers
Question	A multiple-choice or open-ended question requesting information
Answer	An answer representing a defined statement or free text

PPI source names are represented in a “display” field. However, to avoid concept name duplicates, modified PPI names have been made through the parsing of their source codes (values of a “pmi_code” field). Original “display” values were put into the CONCEPT_SYNONYM table.

If a PPI concept has a standard LOINC or SNOMED equivalent, it is considered to be Non-standard. If a PPI concept does not have a standard LOINC or SNOMED equivalent, it is considered to be Standard. However, these concepts are meant to be used in the All of Us context and standard concepts in PPI should normally not be used as target concepts in ETL steps for other OMOP CDM implementations.

PPI source type value	Concept Class	Domain
Module	Module	Observation
Topic	Topic	Observation
Question	Question	Observation
Answer	Answer	Observation
Protocol modification	PPI Modifier	Observation
Physical measurement	Clinical Observation	Measurement

Relationship	From	To	Reverse Relationship
PPI parent code of	PPI Module	- Respective PPI Topic - Respective PPI Question - Respective PPI Answer	Has PPI parent code
	PPI Topic	- Respective PPI Topic - Respective PPI Question - Respective PPI Answer
	PPI Question	- Respective PPI Topic - Respective PPI Question - Respective PPI Answer
	PPI Answer	- Respective PPI Question OR Topic
Answer of (PPI)	PPI Answer	- Respective Standard PPI Question	Has answer (PPI)
Maps to	PPI Module	The same PPI Module as a Standard concept	Mapped from
	PPI Topic	The same PPI Topic as a Standard concept
	PPI Question	The same PPI Question as a Standard concept
	PPI Modifier	The same PPI Modifier as a Standard concept
	PPI Clinical Observation	The same PPI Clinical Observation as a Standard concept
Maps to (obligatory with “Maps to value”)	PPI Answer	Standard PPI Question or Topic	Mapped from
Is a	PPI Topic	- Parental Standard PPI Module - Parental Standard PPI Topic - Parental Standard PPI Question	Subsumes
	PPI Question	- Parental Standard PPI Module - Parental Standard PPI Topic - Parental Standard PPI Question

A purpose of External PPI relationships is the following:

• to build PPI-LOINC-SNOMED hierarchical crosswalks based on the Internal PPI Hierarchy.
• to simplify s cross-analysis of patient-related information with a context of combined use of the PPI and other coding systems.

Relationship	From	To	Reverse Relationship
Answer of (PPI)	PPI Answer	Standard LOINC/SNOMED equivalent of a parental Non-standard PPI Question	Has answer (PPI)
Maps to	PPI Question	Standard LOINC/SNOMED equivalent	Mapped from
	PPI Clinical Observation	Standard LOINC/SNOMED equivalent
Maps to (obligatory with “Maps to value”)	PPI Answer	Standard LOINC/SNOMED equivalent of a parental Non-standard PPI Question or Topic	Mapped from
Maps to value (obligatory with “Maps to”)	PPI Answer	Standard LOINC/SNOMED equivalent of an Answer value	Value mapped from
Is a	PPI Question	Standard LOINC/SNOMED equivalent of a parental PPI concept	Subsumes
	PPI Topic	Standard LOINC/SNOMED equivalent of a parental PPI concept

The PPI Hierarchical crosswalks include only standard concepts. A PPI standard concept value depends on the existence of an equivalent mapping either to the SNOMED or LOINC. A standard SNOMED/LOINC equivalent, if present, takes the place of a non-standard PPI concept in the Internal PPI Hierarchy and adopts all its ancestors and descendants.

1) Mapping of PPI Questions Note, that for the answers-containing Topics the same logic was used.

2) Mapping of Answers

3) Mapping of Measurements