# Data-Quality Framework (DQF)

YourPHR consumes FHIR from many vendors of varying quality. To make import, classification, display, and testing decisions *principled* rather than ad-hoc, we need two things written down:

1. __Our DQF__ — what "data quality" *means* for a patient-facing PHR, and how we respond to each kind of defect.
2. __Source DQF profiles__ — the quality we actually get from each data source, including what we have *not* yet characterized.

This is the conceptual backbone of [`testing-and-data.md`](./testing-and-data.md) (how we test it), [`test-sandboxes.md`](./test-sandboxes.md) (where the data comes from), and [`../your-phr-dashboard/classification-and-display-architecture.md`](../your-phr-dashboard/classification-and-display-architecture.md) (the two-layer ingest→display pipeline that *produces* the legible display this DQF governs).

## Part 1 — YourPHR's DQF (our doctrine)

### The three dimensions

We adopt the well-established __Kahn et al.__ clinical-data-quality framework (the same one the OHDSI Data Quality Dashboard and the [PHUSE-US 2024 IBM paper](https://www.lexjansen.com/phuse-us/2024/ic/PAP_IC12.pdf) use), interpreted for a patient PHR:

| Dimension | The question | In our data |
|---|---|---|
| __Conformance__ | Are values drawn from interoperable code systems / expected value sets? | Extensible/example value sets get __locally-defined codes__ — e.g. Epic `Encounter.class` = `HOV` (a local code) while `type[].text` is the readable "Outpatient". |
| __Completeness__ | Is a required/expected element present? | US-Core-optional fields are routinely absent; some exports omit whole resource types (a documents-only export with no `Encounter`). |
| __Plausibility__ | Do values make sense, alone and across fields? | A recorded date before birth or after death or in the future; an out-of-range value. |

### The critical inversion: we *tolerate and display*, we do not *reject*

Research/pharma uses this framework to judge whether a dataset is __fit for analysis__ and to __exclude__ data that fails. __A patient PHR must do the opposite.__ These are the patient's own records — excluding imperfect data means *hiding the patient's data from them*, which is mission failure ("Your medical records, immediately and in your hands — for free.").

So every quality failure maps to a __display behavior, not a gate__:

| Failure | Our response |
|---|---|
| __Conformance__ — non-standard / local code | Prefer the human-readable `text`; show the raw code only as a detail, never as the primary label. (The HOV → "Outpatient" fix, [#262](https://github.com/jwilleke/yourphr/issues/262).) |
| __Completeness__ — missing element | Show __"unknown"__. Never blank, never fabricate or infer a value. (The no-guessing display principle.) |
| __Plausibility__ — impossible value | Show it __and flag it__ ("recorded date precedes birth — check source"). Never silently correct or drop it. |

### Honesty principles (the spine of all three)

- __Display only what the record states.__ Derive nothing the source did not assert.
- __Absence is "unknown,"__ not zero, not a guess.
- __Surface provenance__ — which source/record a value came from — so the patient can judge it.
- __Flag, don't fix.__ We are a faithful viewer, not a data-cleaning pipeline.

### Where the DQF shows up in the app

- __Import__ — skip-and-survive: never crash on a malformed or partial bundle; report honest counts.
- __Classifiers__ — fall back across dimensions (e.g. `class` when `type[]` is absent) rather than assuming US-Core conformance.
- __Display__ — the legibility behaviors above ([#262](https://github.com/jwilleke/yourphr/issues/262)).
- __Testing__ — golden assertions organized by the three dimensions ([`testing-and-data.md`](./testing-and-data.md)).

## Part 2 — Source DQF profiles

What we know about each source's data quality. __Characterized__ is honest about how much we have actually inspected — most sources are one export or not yet connected, so treat "quirks" as *observed so far*, not exhaustive.

| Source | US-Core baseline | Known quirks (observed) | Our handling | Characterized |
|---|---|---|---|---|
| __Synthea__ | aligned (synthetic) | "too clean" — never reproduces vendor non-conformance | happy-path baseline | ✅ well-understood (synthetic) |
| __Epic__ (sandbox) | US-Core | `Encounter.class` is a LOCAL patient-class code (`HOV`/`Admission`, __not__ v3-ActCode) so `legibleClass()` misses; clinical resources dual-code SNOMED/ICD/LOINC/CPT __inline__; pre-Nov-2022 exports use OID code systems (newer use standard URLs); generated CDAs carry a Care-Everywhere perf table; __sends no `meta` at all__ — no `versionId`, no `lastUpdated` (see [version signals](#version-signals--did-this-record-change)) | prefer the standard coding when present; `type[].text` for local-only fields (`class`, `Goal`); strip CDA perf telemetry. See [`../vendors/epic/notes.md`](../EHR-vendors/epic/notes.md) | 🟡 one patient (Camila) |
| __Oracle Health (Cerner)__ | US-Core | the `nsmart` export is __documents-only__ (~2,149 `DocumentReference`, allergies, some `DiagnosticReport`) — no `Patient`/`Encounter`; __always sends `meta.versionId` + `meta.lastUpdated`__, stable across calls, yet the authenticated API returns list order unstably (`AllergyIntolerance.reaction[]`, `DocumentReference.category[]` shuffle between passes) | docs-only empty state; treat `DocumentReference` narrative as primary | 🟡 one export |
| __CMS Blue Button 2.0__ | claims profiles | __claims only__ (EOB/Coverage), no clinical resources; no `$everything`; initial token omits `patient`; sends `meta.lastUpdated` but __no `versionId`__ | claims classifiers ([#294](https://github.com/jwilleke/yourphr/issues/294)–[#296](https://github.com/jwilleke/yourphr/issues/296)) | 🟡 connected; data = claims |
| __Veradigm / FollowMyHealth__ | unknown | — | — | 🔴 never pulled data (blocked at auth) |
| __VA Clinical Health__ | US-Core (per docs) | — | — | 🔴 candidate, not connected ([#370](https://github.com/jwilleke/yourphr/issues/370)) |
| __athenahealth__ | unknown | — | — | 🔴 registered, not connected |

### Version signals — did this record change?

A sync receives every record again on every pass. Deciding whether one actually changed decides whether a new version is stored, and up to v3.7.2 we stored one every time: 8.4 GB of identical copies on one household ([#781](https://github.com/jwilleke/yourphr/issues/781)). This section records what we can rest that decision on. Checked 2026-09-27.

__What FHIR R4 requires.__ Only the id. A server "SHALL" return every resource with its `id`. Versioning is a recommendation: servers "SHOULD support versions, but some are unable to"; one that versions fills in `meta.versionId` and `meta.lastUpdated`, and one that does not must leave `versionId` out and still keep `lastUpdated` correct. `meta`, `versionId` and `lastUpdated` are all 0..1. A read "SHOULD" carry the version as an ETag header, which does not help a search. Each server may declare what it does in its CapabilityStatement (`rest.resource.versioning`). US Core adds nothing: `meta` is not must-support.

__What an id is, and is not.__ `Resource.id` is unique only on the server that issued it, for that resource type; it is not a key across vendors. `meta.versionId` names one version on that same server. What links the same real-world thing across providers is the optional, repeating `identifier` (system + value: MRN, NPI, order number). R4 does not require one on every resource, and US Core requires it only on some profiles (Patient, for example). So a provider's copy of a record is keyed by *server + type + id*, and linking two providers' copies goes through `identifier`. It is never assumed from a matching id, and never a silent join. YourPHR keys records without the server today; that is [#784](https://github.com/jwilleke/yourphr/issues/784).

__What vendors actually send.__

| Source | Declares `versioning` | `meta.versionId` | `meta.lastUpdated` | Evidence |
|---|---|---|---|---|
| __Epic__ | not stated (all 60 types) | never | __never__ — though the spec says it should be kept correct | raw sandbox capture (`sample-data/epic/`, 41 records), CapabilityStatement |
| __Oracle Health (Cerner)__ | not stated (all 42 types) | always | always | 2,299 records in `sample-data/oracle-cerner/`; open sandbox, stable across repeated calls |
| __CMS Blue Button 2.0__ | — | never | always | `sample-data/medicare/` |
| __SMART Health IT__ | `versioned-update` | always (a real counter) | always | live open endpoint |
| __HAPI__ (reference server, not a source) | — | always | always | live public endpoint |

So no single field works for every provider, the declaration cannot be the switch either (Cerner sends versions and declares nothing), and content comparison alone is fooled by vendors that reorder lists: five Cerner allergies accumulated ~230 versions each without a single change.

__What others do (checked 2026-09-27).__ The SMART team hits the same wall. Their open-source bulk client, [SMART Fetch](https://docs.smarthealthit.org/cumulus/fetch/since.html) (announced on the [SMART on FHIR list](https://groups.google.com/g/smart-on-fhir/c/tPuH4mJLmTI/m/UvkoYDCNAwAJ), July 2025), says "some vendors don't support the `meta.lastUpdated` field" and names Epic as "a notable example". Their workaround fakes "created since" from per-resource dates such as `DiagnosticReport.issued`, and states the limits plainly:

- it does not see edits to a resource created earlier;
- eight resource types have no searchable creation date (Device, Encounter, EpisodeOfCare, Immunization, MedicationDispense, Patient, Procedure, Specimen);
- for change detection it recommends a full re-export.

Nothing on the list describes a way to tell a changed resource from a repeat on a server that sends no `meta`. A 2017 thread ("Detecting patient changes in the background") calls it "the tricky part" and points at `meta.lastUpdated`. So a full fetch plus our own comparison, which is what we do, is what the people who wrote SMART do too. The difference is that we must compare carefully.

__The rule, adopted for [#252](https://github.com/jwilleke/yourphr/issues/252) (decided with Jim, 2026-09-27).__ Take the best evidence each provider gives, in the spec's own order:

- __`meta.versionId` sent:__ it decides. Same means unchanged; different means changed.
- __otherwise `meta.lastUpdated` sent:__ same means unchanged, newer means changed, older is refused as stale.
- __otherwise__ compare content, with lists of objects compared regardless of order (lists of plain values keep their order), and a generated narrative ignored when the data matches.

Underneath all three: store the provider's `meta.versionId` and `meta.lastUpdated` as it sent them, and keep our own version separately. Until #252 lands we overwrite them on write, which is why the first two rules have nothing to read today.

A documents-only or claims-only source is itself a __completeness__ fact about that vendor — not a bug in our import. Recording it here stops us re-diagnosing "no encounters showed up" as a defect each time.

## Part 3 — How we assert it

The golden-test harness in [`testing-and-data.md`](./testing-and-data.md) is where the DQF becomes executable: each fixture's assertions are tagged to a dimension (conformance / completeness / plausibility), so coverage is systematic rather than incidental. The __OHDSI Data Quality Dashboard__ (Apache-2.0, OMOP-CDM-only — *not* runnable on our FHIR/SQLite stack) is useful only as a __check-type catalog__ to mine: translate the display-relevant subset to FHIR, as the PHUSE paper did. We take its vocabulary, not its 4,000-check analytics scale or its reject-the-dataset framing.

## References

- Kahn MG, et al. — *A Harmonized Data Quality Assessment Terminology and Framework* (Conformance / Completeness / Plausibility).
- OHDSI Data Quality Dashboard — <https://github.com/OHDSI/DataQualityDashboard> (Apache-2.0; OMOP CDM; catalog reference only).
- Ferko S, et al. (IBM), PHUSE-US 2024 — *Data Quality Evaluation of EHR FHIR API Real World Data* — <https://www.lexjansen.com/phuse-us/2024/ic/PAP_IC12.pdf>.
- 21st Century Cures Act (2016) — the interoperable-FHIR-API mandate this project exists to fulfill.