Subject Matter Domain

A common way to sort clinical documents is by the medical specialty of the author (e.g., Cardiology, Endocrinology). This categorization is called the Subject Mater Domain (SMD) in LOINC. However, LOINC has not been adapted for the Canadian naming of standard specialties or the unique subspecialties in Canada.

We reviewed the LOINC list of SMDs with the Royal College of Physicians and Surgeons of Canada (RCPSC). Using the following principles:

• The shortest specialty title chosen from the two SMD sources is preferred because the full document classification display name has character limits. Creation of a shortened SMD synonym is discouraged.
• Pediatric specialties are given unique classifications and display names. A document is considered to be from an adult medicine perspective unless classified as pediatric and therefore does not need the word Adult in the display name.
• The contents of the document should match the SMD assigned, such that the reader is not surprised by the contents. Since a wide variety of specialties can achieve some Area of Focused competency designations (e.g., Transport Medicine AFC can be achieved by Emergency, Intensivists, Anesthesia, etc.), we sometimes need to create SMD for AFCs even though it seem overly specific. This is preferred to the alternative of using only one of the permitted specialties for classification and misrepresenting the document’s contents. For example, it is inaccurate to use the SMD of Anesthesia for a Transport Medicine document so we need the SMD of Transport Medicine.

The LOINC parts that were selected for the SMD come from the following steps. Please note that there are some overlapping SMDs across steps.

In addition, there are some RCPSC specialties in Canada that need to be requested from LOINC. As a short-term measure, we have requested extension codes from Canada Health Infoway.

1. Adolescent and Young Adult Oncology
2. Echocardiography
3. Forensic Pathology
4. Geriatric Psychiatry
5. Medical Biochemistry
6. Neuromuscular Medicine
7. Neuroradiology
8. Pediatric and Perinatal Pathology
9. Pediatric Anesthesiology
10. Pediatric Emergency Medicine
11. Pediatric Radiology
12. Prehospital and Transport Medicine
13. Vitreoretinal

Note: RCPSC does not fully regulate the subspecialties in Canada. There are subspecialties that have a) a national conference, b) a dedicated journal, c) departments within a medical school or university. These will be added to the Canadian Ontology. An example is Vitreoretinal.