Key Takeaways
- UCUM provides a standardized way to represent units of measure, crucial for preventing errors and ensuring accurate data exchange in healthcare.
- Using UCUM standard units in conjunction with FHIR significantly enhances interoperability between different healthcare IT systems by ensuring consistent and precise communication of units.
- The Kodjin FHIR Server includes built-in support for UCUM unit codes, offering features like string validation and value filtering, which streamline data management and improve overall data quality.
Ensuring interoperability between various healthcare IT systems requires multiple standards. Among them is FHIR, developed by the HL7 standards organization, which is the newest and most promising one. Its adoption has significantly grown in the past years. Such standards play a key role in organizing data into comprehensive structures as it moves between systems.
Each health organization, whether a hospital or laboratory, tends to use its own numerical unit representation, depending on various factors. As a result, this discrepancy in data can pose significant challenges to interoperability.
For example, when creating a common database in the FDA’s Mini Sentinel project and then combining the data, researchers have found 68 different platelet count result units in the data. The standardization of numerical data might not seem like a big problem, but it is, especially for interoperability. For this reason, HL7 recommends using UCUM (Unified Code for Units of Measure) when adopting FHIR.
As we’ve been developing our own FHIR product – the Kodjin FHIR Server, we’ve implemented the support for UCUM medical units in our solution. In this article, we’ll cover what UCUM is and how the FHIR UCUM conversion works in detail.
What is UCUM?
To understand the role of UCUM in unit standardization, let’s first examine what it is. UCUM was originally developed by Gunther Schadow and Clem McDonald and is now distributed and made available by the Regenstrief Institute, Inc.
UCUM is a code system that aims to include all modern units of measure used in science, engineering, and business. Its main goal is to provide a clear means of communication between different systems. UCUM works with metric as well as empirical units such as feet and inches.
While typically used for electronic data interchange (EDI) protocols, it can also be applied in other types of machine communication. The code system has been adopted by several large standards organizations, including IEEE, DICOM, HL7, and ISO’s 11240:2012 specification about medicinal product characteristics.
How the UCUM conversion works
The Unified Code for Units of Measure assigns to each defined unit a specific meaning based on dimensional analysis, as it’s not enough for different systems to just use the same symbols to facilitate interoperability. UCUM has a formal syntax that can be validated and a matrix of coefficients that define the values expressed by various commensurate units.
UCUM provides a single coding system for units; as such, it’s easy to see how it can help establish interoperability.
Text describing the complete UCUM syntax in the Backus-Naur Form.
The Complete UCUM syntax in the Backus-Naur Form
<sign> ::= "+" | "-"
<digit> ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
<digits> ::= <digit><digits> | <digit>
<factor> ::= <digits>
<exponent> ::= <sign><digits> | <digits>
<simple-unit> ::= <ATOM-SYMBOL>
| <PREFIX-SYMBOL><ATOM-SYMBOL [metric]>
<annotatable> ::= <simple-unit><exponent>
| <simple-unit>
<component> ::= <annotatable><annotation>
| <annotatable>
| <annotation>
| <factor>
| "("<term>")"
<term> ::= <term>"."<component>
| <term>"/"<component>
| <component>
<main-term> ::= "/"<term>
| <term>
<annotation> ::= "{"<ANNOTATION-STRING>"}"There are many FHIR profiling tools available that help perform a conversion and validation of quantities with UCUM units. However, it’s possible to forgo that step with an FHIR server that provides a built-in UCUM unit conversation.
How the FHIR UCUM Conversion works in Kodjin
Our team has implemented full support for the UCUM expression syntax in our Kodjin FHIR server. It is part of the Kodjin FHIR suite and has two main functions:
String validation
The server checks to see if the entered string matches the unit code in the UCUM codes table. If not found, the string is tested for typical syntax errors such as missing brackets. The error and its reason are then reported in a message box.
Filtering by value
This function converts numerical values and filters data in base units. When no exact match for a unit name is found, the server searches for all possible units with a single search term corresponding to the unit’s synonyms or name.
Such filtering can be done in meters, even if the source data is in feet or centimeters. The system understands that 170 centimeters are equal to 1.7 meters, for example.
Conclusion
Incorporating UCUM into your FHIR-based systems is crucial for ensuring seamless interoperability across diverse healthcare IT infrastructures.
Having the UCUM conversion capabilities built into your FHIR server saves you time and improves data quality, as you won’t have to manually load, validate, and convert all the unit’s data with third-party tools. The Kodjin FHIR server, with its built-in UCUM conversion capabilities will streamline this process, providing support for both string validation and value filtering. This not only saves time but also ensures the integrity of your data.
Contact us to learn more and get a demo of our Kodjin FHIR server that supports UCUM conversion.
FAQ
What are the commonly used UCUM codes for healthcare units?
Commonly used UCUM codes include units of length such as meter (m), centimeter (cm), and millimeter (mm); units of mass like gram (g), kilogram (kg), and milligram (mg); and units of volume, including liter (L) and milliliter (mL). Time units are second (s), minute (min), hour (h), and day (d). For temperature, Celsius is represented as Cel, and Fahrenheit as [degF]. Concentration units include millimole per liter (mmol/L) and gram per liter (g/L).
What are the differences between representation of codes for UCUM in FHIR v OMOP?
FHIR uses UCUM codes directly for unit representation, ensuring consistent and unambiguous communication of units across different systems. In FHIR, the unit of measure is typically included in the valueQuantity field, which consists of a value and a unit (UCUM code).
On the other hand, OMOP also uses UCUM codes but may involve mapping to standardized vocabularies within the OMOP Common Data Model (CDM). OMOP’s approach is more focused on observational data and research, often involving extensive data normalization processes. Units of measure in OMOP are stored in the measurement table, where the unit_concept_id links to a standard concept for the unit.
Can UCUM codes be used for non-clinical data in FHIR systems?
Yes, UCUM codes can be used for non-clinical data in FHIR systems. UCUM is designed to be a comprehensive coding system for units of measure, including those used in various fields such as science, engineering, and business, in addition to healthcare.
This versatility makes UCUM suitable for representing a wide range of data types within FHIR systems, ensuring consistent and standardized communication of units across different domains.
