OHIP Diagnostic Codes (Ontario) Code system¶
| Canonical | ../CodeSystem/on-ohip-diagnostic-codes |
|---|---|
| Status | draft · 1.26.0 |
| Content | not-present |
| Source | FSH · JSON |
Ontario's own three-digit diagnostic code set -- the second code on an OHIP physician claim, alongside the fee code from OHIP Schedule of Benefits.
This artifact enumerates no codes. It declares the system so that a diagnostic code pinned to it is recognisable as an Ontario diagnostic code and the system URI resolves to a definition. Obtain the concept list from the Ontario Ministry of Health.
This set is ICD-9-LIKE, and that is the trap¶
Ontario's diagnostic codes share many codes with ICD-9 but the set is NOT a subset of ICD-9. Do not derive one by truncating an ICD-9 code. The range 895-971 is a parallel Ontario space laid over ICD-9 numbers already occupied by something unrelated:
| code | means, in Ontario | means, in ICD-9 |
|---|---|---|
970 |
Other Acceptable Diagnosis: Prenatal Care | poisoning by CNS stimulants |
967 |
Immunization: Influenza | poisoning by sedative |
Measured against the Provincial Health Care Vocabulary Standard, a SNOMED CT -> ICD-9 -> truncate
route reaches only 69.4% of cases, and 124 of them land inside 895-971 and come out valid
and wrong -- "Poisoning caused by opioid receptor agonist" becomes 970 Prenatal Care, "Pica"
becomes 307 Sleep-Wake disorders. Nothing downstream rejects those. They go on a claim, they
adjudicate, and the diagnosis on the record is not the diagnosis the clinician made.
Matching on description text instead is the same inference wearing different clothes, and it runs
out anyway: the set has no concept for stage-3 chronic kidney disease, and the nearest neighbours
for Alzheimer disease and stable coronary artery disease (290 Senile dementia, 413 angina
pectoris) each say something the chart does not.
A code alone does not even determine a concept within the set: eighteen codes carry two unrelated
meanings (072 is both "Mumps" and "Gait Training"), so the mapping is to a concept, not to a
number.
Map to this set explicitly, from its own concept list. Never compute it from ICD-9. Where no correct code exists, a wrong diagnostic code is worse than an absent one -- it adjudicates.
Codes are three characters, zero-padded (for example 250). Case-sensitive.
No canonical is published upstream. Ontario does not publish a FHIR canonical for this set, so this specification names one. The URI is stable and will not be changed.
All codes from this system.