Logical Observation Identifiers Names and Codes (LOINC)
Kristin Jonsdottir, Seng-Chee Lee, Jennifer O'Neil, & Janelle Tepper
University of Minnesota
The Logical Observation Identifiers Names and Codes (LOINC®) is a database that provides a universal code system for reporting laboratory and other clinical variables, reports and orders. Its purpose is to identify observations in electronic messages such as Health Level Seven (HL7) observation messages (C. J. McDonald?
et al., 2003).
The development of LOINC is divided into three divisions. The first and the largest division is the laboratory LOINC which covers all fields of laboratory medicine. The second, clinical LOINC is concerned with non-laboratory diagnostics, critical care and nursing measures as well as the history, physical and survey instruments (Clement J. McDonald?
& National Institutes of Health (U.S.), 2007). The third and newest division focuses on proposals for the Health Insurance Portability and Accountability Act (HIPAA) attachments. The attachments already drafted are: laboratory reports, non-laboratory clinical reports, ambulance transport, emergency room visits, medications, and rehabilitation (C. J. McDonald?
et al., 2003).
The newest version of LOINC, 2.21 contains 48,600 terms, 35,547 laboratory, 10,468 clinical, 921 claims attachments and 1,664 surveys ("LOINC", 2007).
Each record in the LOINC database identifies a clinical observation and contains a formal 6-part LOINC name, a unique code with check digit, the observation class (e.g., chemistry, hematology and radiology), related names and synonyms, a short more readable name and fields for mapping and other information.
The LOINC name consists of the following fields or axes: code, component, property, timing, specimen, scale, and method.
• The Code is a meaningless number with check digit.
• Component is the name of the observations e.g. glucose, diastolic blood pressure.
• Property is what is being measured e.g. mass, length, area, pressure, temperature.
• Timing explains when the observation is done e.g. point in time, study minimum.
• Specimen field stores the type of specimen used for the test e.g. urine, patient, ventilator setting. A distinct LOINC code is required for each specimen for which a test kit has been validated.
• Scale e.g. quantitative, ordinal, nominal, narrative
• Method states how the value is found e.g. stated, measured, estimated, ultrasound, spirometer.
The first five parts are mandatory but method is optional and is only used when the method distinction makes an important difference to the clinical interpretation of the result. Subparts of the six axes are created as needed in specific subject areas. Up to 13 sub components of a LOINC term have been made. The terms are linked in a hierarchy and recently they have been grouped in panels and the database now also includes codes for some test packages (panels) such as arterial blood gases but only the most common and standardized ones.
Radiology is a special subgroup in LOINC. The component part of the name is set forth in Expression Pattern 5 which includes projection, body part, orientation, position and a number.
LOINC also provides codes for documents types like Clinical notes and Patient reports. These codes were created to provide consistent semantics for the names of documents when they are shared or exchanged between independent facilities or enterprises. The model for the document records is:
• Kind of document: Clinical Note, letter, consent, reference document.
• Type of service: Consult, Education, Evaluation and Management.
• Setting: Hospital (inpatient), Clinic (outpatient), Nursing home.
• Subject matter domain: Cardiology, Endocrinology, Pathology, Chaplain.
• Training/professional level: Nurse, Social Worker, Physician, Attending.
A mapping program called Regenstrief LOINC Mapping Assistant (RELMA™) is available with the database, to assist the mapping of local test codes to LOINC codes and to facilitate browsing of the LOINC results. Both LOINC and RELMA are available at no cost from http://www.regenstrief.org/loinc/
. RELMA can also be run over the internet using your web browser.
Intended Uses and Settings
According to the Regenstrief Institute, the purpose of Logical Observation Identifiers Names and Codes (LOINC) is “to facilitate the exchange and pooling of results, such as blood hemoglobin, serum potassium, or vital signs, for clinical care, outcomes management, and research” (http://www.regenstrief.org/medinformatics/loinc/
). At this time, the majority of laboratories and other diagnostic centers electronically transmit results from their reporting systems to their care systems using Health Lesson 7 (HL7). Unfortunately, each laboratory or diagnostic center typically has their own individual code values making it difficult or impossible for care systems to comprehend and accurately organize the data it receives. “The LOINC laboratory terms set provides a standard set of universal names and codes for identifying individual laboratory and clinical results” (Regenstrief Institute, 2007).
Because LOINC is standardized, it specifically allows care systems to merge clinical and laboratory results into one database for patient care, clinical research, or management. In a 1996 article describing the LOINC database, the authors suggested that the LOINC database should ultimately be of interest to “hospitals, clinical laboratories, doctors’ offices, state health departments, governmental healthcare providers, third-party payers, organizations involved in clinical trials, and quality assurance and utilization reviewers” (Forrey, et al., 1996).
Potential Benefits in Clinical Practice
The LOINC system database allows consistency in communication, documentation and collaboration between different services such as: nursing, laboratory, physicians, dental and case managers to name a few. The system covers topics ranging from anesthesiology to veterinary medicine, encompassing a large variety of specialties (Huff, 2006).
In relation to nursing, the Regenstrief Institute, which maintains the LOINC database, has a nursing subcommittee that has developed a desired mission and action for the system. This makes the LOINC system particularly “nurse friendly” while still offering services for the other specialties.
With entered language, the program seeks out terms in a broadened database that allows for method specific and methodless specific results. Another benefit of LOINC is that it can be used in conjunction with the widely used HL7, which allows hospitals to reduce the amount of software because the programs work together (Regenstrief Institute, 2007).
The RELMA system, which enhances LOINC, ‘maps’ the facilities terminology and allows for the sharing of information between facilities. Both programs are offered for free through the Regenstrief Institute. These programs allow for the ability to transfer laboratory and test results, vital signs, clinical observations and progress notes from facility to facility and compile the information into one database. It can be used in an assisted living home, home health care, nursing homes and hospitals and in the outpatient clinics. One of the main benefits of the LOINC system is this ability for communication between so many different specialties and facilities (Regenstrief Institute, 2007).
There is also a new option that changes the linguistic options of the program without restarting the program and even offers a menu option to set the preferred language. This is a large benefit when dealing with international information (Regenstrief Institute, 2007).
There is also the issue of privacy when sensitive information such as this is available and the LOINC system works with Health Insurance Portability and Accountability Act (HIPAA) of 1996 to maintain confidentiality. HIPAA supports the LOINC system because of its cost efficiency and safety with information and electronic claims. Because the LOINC system can be widely used, the need for involvement from other parties is unnecessary, keeping patient information private (Regenstrief Institute, 2007).
The development LOINC was initiated by the LOINC committee at Regenstrief Institute in association with Indiana University in 1994 (Huff, S., Rogha, R., McDonald?
, C., Moor, G., Fiers, T., & Bidgood, W., et al., 1998). Initially, the committee aimed to create a list of observation identifiers (laboratory tests and clinical observations) that could be used in HL7, ASTM 1238, CEN TC251/PT3-008 and PT3-002 (Huff, 1998). The committee selected a small group of physicians, chemists, laboratory managers and other specialists that would contribute to deciding the codes and names as the observations identifiers. After that, the committee went onto to develop a multi-axial model with substantial vocabulary content, which was greatly influenced by SNOMED, IUPAC, and EUCLIDES, Open-Labs, and CEN TC251/ PT3-008. The system evolved through four different models before its introduction in 1995.
The first LOINC vocabulary, laboratory tests specifically, was released in March 1995 for external review (Huff, 1998). In 1997, clinical observations were added to its vocabulary content. The first widespread use of LOINC by different systems took place in August 1998. At the same time, Regenstrief offered free download of RELMA, which is important for mapping local vocabulary to LOINC terms (McDonald?
, C., Huff, S., Suico, J., Hill, G., Leavelle, D., Aller, R., 2003)
HIPAA recognized the potentials of LOINC by proposing its use in adjunction (United States Health Information Knowledge (USHIK, 2005). In 1999, LOINC was identified by the HL7 Standards Development Organization as standard code. The popularity of LOINC grew rapidly and was adopted by many federal organizations and commercial laboratories including U.S Veterans Administration, U.S. Navy, CDC, Kaiser Permanente, Quest Diagnostics, LabCorp?
, etc (Huff, 1998). LOINC has also been endorsed by American Clinical Laboratory Association and Andover Working Group for Open Healthcare Interoperability.
In 2002, the American Nurses Association (ANA) recognized LOINC as a nursing terminology (Matney, 2003). Nursing content has been included into the LOINC database and developed by a subcommittee of Clinical LOINC over the last few years.
The Departments of Health and Human Services, Defense, and Veterans Affairs announced the standards for the electronic transmission of clinical information for all federal organizations in 2003. Consolidated Health Informatics (CHI), an initiative of United States Health Information Knowledgebase (USHIK), appreciates the widespread acceptance of LOINC and recommends additional financial support from the government.
Revisions of LOINC database occur 3 to 4 times per year. Currently, LOINC version 2.21 contains 48,600 terms, an increase of 1,788 since the December 2006 version (Regenstrief Institute, 2007). LOINC has also been adopted by many foreign countries as standard code set, which include Canada, Germany, Switzerland, Australia, Korean, Estonia, Brazil, and New Zealand. It is also available in Chinese, German, and Spanish.
LOINC is widely used and well established and is now one of the source vocabularies in the Unified Medical Language System (UMLS) and Metathesaurus from The National Library of Medicine (NLM).Today most laboratory and diagnostic systems in the US deliver their results electronically via HL7 messages to hospitals, office practice, health maintenance organizations (HMOs), public health departments and other clients. One HL7 record is sent for each separate test observation. The observation identifier is carried in the OBX-3 field and the observation value in OBX-5. The LOINC code is used as the observation identifier or the name of the observation in standards other than HL7. The LOINC code can also be used to order the observation.
Large reference laboratories like Quest and LabCorp?
, are now using LOINC codes along with their local codes in HL7 result messages (C. J. McDonald?
et al., 2003). Other large laboratories and the 26 veterinary medicine laboratories in the US are also mapping their local test codes to LOINC (Clement J. McDonald?
& National Institutes of Health (U.S.), 2007). Large healthcare institutions are using LOINC to standardize the information coming from many different sources. Notable users include Partners Health-Care of Boston, Intermountain Health Care, Kaiser Foundation Health Plan, the Hospital for Sick children in Toronto, all of the major hospitals in Indianapolis, New York-Presbyterian, and the University Hospitals of Columbia and Cornell. Many health insurance companies require their laboratory vendors to supply them with LOINC-coded laboratory HL7 messages so that they can pool these results for clinical management purposes (C. J. McDonald?
et al., 2003).
Most federal agencies with healthcare interests have adopted LOINC. The New York State Public Health Department, Indiana State Department of Health, and Washington State Public Health Laboratories are using LOINC to deliver laboratory results that identify cases of reportable conditions to public health departments (Overhage, Suico, & McDonald?
LOINC codes are also used with other message standards than HL7 such as; the Clinical Data Interchange Standards Consortium (CDISC), which includes all of the major pharmaceutical manufacturers and the Food and Drug Administration as a liaison participant, and which uses LOINC codes for identifying laboratory tests and EKG results in new drug submissions ("CDISC Submissions Data Domain Models Version 2.0 ", 2007). Digital Imaging and Communication in Medicine (DICOM) also uses LOINC in some Cardiac Echo and OB ultrasound specifications and will likely also use it for radiology reports. Finally, HIPAA Attachment standard requires LOINC for the coding of observation categories and a time window in data requests and structured data responses (C. J. McDonald?
et al., 2003).
There are several international users of LOINC as well. In Germany, LOINC has been specified as a national standard for laboratory reporting. In Switzerland, the Swiss Center for Quality Control introduced a LOINC-based service, CUMUL, which has contributed their French, German, and Italian names for close to 3600 of the most common laboratory tests to the LOINC database. LOINC is part of a province-wide laboratory information standardization in Ontario and British Columbia and is used in Australia, Korea, Estonia, Brazil, China, Netherlands, New Zealand, Hong Kong and in the Paris hospital system. LOINC has been fully translated into Spanish and Simplified Chinese (Clement J. McDonald?
& National Institutes of Health (U.S.), 2007).
The interest in having laboratory instruments deliver LOINC codes with the results they produce has recently increased and some instrument vendors, including Dade MicroScan?
’s antibiotic susceptibility and Beckman Coulter’s cell counting instruments, have been mapping each of their distinct instrument measurements to LOINC codes for years. Roche Diagnostics now has mapped all test measurements produced by their large-scale chemistry analyzers to their corresponding LOINC codes. The involvement of instrument vendors can facilitate the implementation of LOINC because the have the most knowledge identify the appropriate LOINC code and/or to argue for new LOINC codes when required by new testing technology. In addition, when instrument vendors provide LOINC codes as part of the result output message, they decrease the need for mapping work at the hundreds of laboratories that use their instruments. Some LIS vendors, including Compromed, M/Mgmt, McKesson?
, Northern, Soft Computer, and Sysware, provide the full LOINC database with each new installation and many now include an indexed field for the LOINC code in their test database (C. J. McDonald?
et al., 2003).
Literature Review of Usefulness
LOINC has been viewed as a largely successful way of standardizing laboratory result transmission. LOINC codes are being used by a variety of different organizations in both the government and private sector as noted in the Extent of Use section above. One of the main reasons LOINC has been so successful is due to the vast number of descriptors required by laboratory tests. One test might require the following information: parameter name; a brief description (in cases where this parameter is not a standard one in routine use); the source of the biological sample (blood, plasma, serum, urine, etc.); the timing of the sample (random vs. collected at a particular time; single sample vs. a cumulative sample collected, for example, over 24 h); the units of measurement; the lower and upper limit of ‘normal’ values, if known (can vary from lab to lab and with age, sex and physiological state, (i.e. pregnancy and lactation)); a bibliographic reference to the test method, if standard (if nonstandard, a reasonably detailed description of how it is performed—i.e. chemical or immunoassay, the reagents used, etc.) (Nadkarni, 2003). LOINC simplifies this process by allowing the user to specify that a parameter is a clinical test or observation and locate the parameter in LOINC by specifying one or more keywords. LOINC entries, in turn, provide many of the details decreasing the number of details that need to be manually supplied.
Most of the literature relates that issues with LOINC are not errors in LOINC itself, but already existing inaccuracies at the laboratory level. In other words, there can be difficulty in the transformation from a labs current code system to LOINC. LOINC is simply an attempt at fixing the problem of diverse naming among laboratories. However, “retrospective mapping of current laboratory information system test names to standard identifiers and naming systems such as LOINC is a labor-intensive process. Even with automated mechanisms the costs of retrospective mapping are considerable for individual health care systems” (Frassica, 2005). Frassica goes on to suggest that this process is even more labor intensive and costly in areas such as the ICU given the huge number of laboratory tests included in LOINC which may or may not be necessary for an ICU.
Dr. Frassica “identified a small subset of the LOINC database that should be the focus of efforts to standardize test names in ICU information systems. Mapping this subset of laboratory tests and profiles to LOINC vocabulary will simplify the process of collecting data for large-scale databases such as ICU scoring systems and the configuration of new ICU information systems.” The LOINC nomenclature is a work in progress, but does include standardized naming for common panels and currently includes nomenclature for some of the most commonly used testing batteries such as the basic metabolic panel (Frassica, 2005). Further categorization of LOINC for more efficient mapping would be valuable for difference specialties in addition to the ICU, including: Obstetrics, Emergency Medicine, Neonatology, Neurology, etc.
In an effort to standardize laboratory data by mapping to LOINC, Kahn, et al. found that they were able to semi-automatically map over 2/3 of laboratory tests from five Indian Health Service medical facilities (2006). The authors that the majority of failures of the automated mapping tool were due to local naming choices. Either there was incomplete information about the test names or the test names differed because of the facility’s naming convention. For example, the names of the test for blood platelets in use in different facilities was Plt, Plat, and Platelets. One of the major inconsistencies was seen in the units of measure of a laboratory test. Either the units were missing or were described differently (e.g., micrograms were referred to as mcg or mg).
Over the past few years the LOINC database has expanded and now includes assessment items which are relevant to nursing. In fact, as noted earlier, in 2002 LOINC met the criteria for “recognition” by the American Nurses Association. There are a variety of different assessment measures in LOINC, including: those related to vital signs, obstetric measurements, clinical assessment scales, assessments from standardized nursing terminologies, and research instruments (Matney, Bakken, & Huff, 2003). As mentioned above LOINC is continually evolving. Additional content is necessary in order for LOINC to be more useful in implementing information systems that support nursing practice. Additionally, the individuals responsible for implementing systems for nursing practice must be able to appropriately link LOINC codes for assessments with other aspects of the nursing process, for example, diagnoses and interventions. “Such linkages are necessary to document nursing contributions to healthcare outcomes within the context of a multidisciplinary care environment and to facilitate building of nursing knowledge from clinical practice” (Matney, Bakken, & Huff, 2003).
Overall, the literature suggests that LOINC is a particularly useful tool. It was also found that LOINC is continually evolving. With improvements it can become an even more valuable instrument for a variety of specialties and for nursing in particular.
Strengths and Limitations
Although the LOINC system has several positive options, there are also some limitations of LOINC in relation to usability, and applicability in the community. The CDC, which uses LOINC, HL7 and SNOMED, found that the “standards” and “vocabularies”, reporting didn’t “function particularly well in public health applications” (CDC, Emerging Infectious Diseases, 2003). There were problems with double reporting of preliminary results and final results, duplicating the reporting of the incidence with the program unable to distinguish the two. There were also problems in other public health environments with the transmission of reports from the “county of diagnosis to the county of residence” (CDC, Emerging Infectious Diseases, 2003).
Reviewing the LOINC PowerPoint?
(Huff, 2006), there were other limitations that were noticed. Although one of the strengths of the LOINC system is the ability of use from a wide variety of specialties, one of the limitations to the system is the complexity of the search engine. Though the terms may be easily readable and navigated by laboratory personnel, it is easy to see how someone not familiar with the six axes and how to use them may actually find more difficulty in using the database. When looking for a particular item, there are several options to choose from and one may spend an unnecessary amount of time looking for information.
Some of the other strengths include international usability, including the linguistic options, the wide variety of specialties included, and the large database of laboratory terminology. Another benefit of LOINC, along with RELMA, is the no-cost factor.
Without actually having used the database and based on information received from reviews and the LOINC web site, it appears that the list of benefits outweigh the difficulties that have been reported in regard to the use of the LOINC system.
From a nursing perspective, the major implication would be the expansion the nursing content in the LOINC database. According to Matney (2003), there are more “cardiovascular assessments, genitourinary assessment, and air ambulance” being submitted to enhance the nursing content.
Although the majority of LOINC terms are used in laboratory settings, the LOINC committee is also working on expanding its content to include other clinical utilities: diagnostic studies, critical care, the history and physical, and survey instruments, clinical notes, report titles, and dental observations (USHIK, 2005).
Other areas of practice, which the LOINC committee has been interested in, include public health and veterinary medicine. Environmental and homeland security related tests are being developed and included in its content (USHIK, 2005). The use of LOINC in veterinary medicine is limited, but potentially beneficial.
Education & Research
Several research interests have been recommended by CHI, which include improvement and evaluation of the terminology models, standardized assessments, and hierarchical structure of LOINC (USHIK, 2005). The terminology models of LOINC are currently limited to laboratory tests and clinical specifications. Standardized assessments, that are used to classify different types of information, are important for data sharing. There is a need to evaluate how different standardized assessments within LOINC will promote information usage. As a result, hierarchical structure of LOINC becomes critical because of the integration of new terminology models and standardized assessment. An improvement in hierarchical structure will also ease the use of LOINC terms by the vendors and institutions.
The LOINC committee is also working on panel naming. Panel coding and test result names have been problematic. The committee is working to find solutions that will allow vendors to adopt LOINC content more efficiently.
Genomic testing is another area of interest. The LOINC committee is working on expanding “gene array and proteomic based laboratory tests (USHIK, 2005).”
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