MedlinePlus Connect: Planning for Clinical Coding System Changes

BACKGROUND

MEDLINEPLUS.GOV & MEDLINEPLUS CONNECT

MedlinePlus.gov is a free consumer health website produced by the NLM. It provides up-to-date health information in easy to understand language. One aspect of MedlinePlus are its Health Topics. MedlinePlus has nearly 900 Health Topics that provide authoritative information on diseases, illnesses, health conditions, and wellness issues. The MedlinePlus Health Topics provide the backbone for the MedlinePlus website. Each Health Topic has its own page on MedlinePlus that provides information regarding symptoms, causes, treatment and prevention, as well as links to authoritative health information sites. The Health Topics are also available via an XML vocabulary file and include a list of synonyms, see references, and MeSH headings for some topics². The MedlinePlus Health Topics are represented within the Unified Medical Language System (UMLS) as a resource for people who need a list of consumer health terms³.

MedlinePlus Connect provides a way for Electronic Health Records or Patient Portals to link to MedlinePlus in order to provide targeted consumer health information to patients, families, and health care providers. To do this, MedlinePlus Connect accepts requests for information on diagnoses, medications, and lab tests from an electronic health record, and returns related MedlinePlus information, including Health Topics. For diagnosis or problem code requests, MedlinePlus Connect links ICD-9-CM codes and SNOMED CT CORE Problem List Subset concepts to Health Topics. MedlinePlus Connect also matches NDCs (National Drug Codes) or RXCUIs (RxNorm concept unique identifiers) to medication information and LOINC (Logical Observation Identifiers Names and Codes) to lab test information [1, 2]. The MedlinePlus Connect application programming interface (API) conforms to the Health Level 7 (HL7) Infobutton specifications.

The MedlinePlus Connect team initially created mapping guidelines (see APPENDIX D: ORIGINAL MAPPING GUIDELINES) to determine the best way to associate ICD-9-CM codes with up to three Health Topics. In 2008, the MedlinePlus Connect team worked with Lister Hill Center (LHC) researchers to increase the number of associations between MedlinePlus Health Topics and the ICD-9-CM code set. LHC researchers used an algorithm similar to the Restrict to MeSH algorithm⁴ that uses relationships within the UMLS to create mappings between ICD-9-CM and the MedlinePlus Health Topics. The MedlinePlus Connect team manually reviewed the algorithm’s resulting 2500 mappings, many of which were incorrect and therefore required extensive review. The MedlinePlus Connect team hand mapped an additional 10,000 codes. The MedlinePlus Connect team manually updates the mappings with each ICD-9-CM release. The team also monitors null responses and develops new health topic pages.

It is essential that MedlinePlus Connect support the next version of the International Classification of Disease, ICD-10-CM, by October 2013. To do so, the MedlinePlus Connect team must create mappings between the Health Topics and ICD-10-CM.

ICD-9-CM AND ICD-10-CM

MedlinePlus Connect currently returns specific Health Topics for problem code requests from two clinical vocabularies used to code medical records for diagnoses. This section focuses on one of those vocabularies, the International Classification of Disease (ICD). The ICD originated in the 1890s to classify international mortality and morbidity [14] and is currently published by the World Health Organization (WHO) to “promote international comparability in the collection, processing, classification, and presentation of mortality statistics” [3]. The WHO owns, publishes, and authorizes adaptations of ICD. The U.S. uses a clinical modification (CM) of the ICD. This clinical modification (CM) is used in the U.S. to assign codes in inpatient, outpatient, and private practices settings and is primarily associated with U.S. billing and reimbursement purposes.

The current version used in the U.S. is the International Classification of Disease – 9^th edition – Clinical Modification (ICD-9-CM). ICD-9-CM was developed by the National Center for Health Statistics (NCHS) in 1977 and adopted in 1979 for use in the United States [5, p. 15]. The Health Insurance Portability and Accountability Act of 1996 (HIPAA) made ICD-9-CM a national standard code set. ICD-9-CM is comprised of three volumes. The first two volumes include diagnosis related codes and disease and health condition codes while the third volume includes procedure codes for inpatient use. The ICD-9-CM coding system consists of a core classification of three to five-digit codes and is hierarchically structured [16]. NCHS and CMS oversee changes and updates to ICD-9-CM.

After WHO developed ICD-10 in 1992, the NCHS developed the initial draft of the clinical modification of ICD-10 for use in the US in 1997 in collaboration with “a Technical Advisory Panel and extensive additional consultation with physician groups, clinical coders, and others to assure clinical accuracy and utility” [10]. CMS maintains ICD-10-CM Volume 3 and ICD-10-PCS for inpatient procedure reporting [5, p. 5]. In 2009, Health and Human Services (HHS)/CMS required the adoption of ICD-10-CM/PCS to replace ICD-9-CM by October 1, 2013 for all covered entities⁵ [5, p. 19]. The 2011 release of ICD-10-CM⁶ is the most recent release available. The next release will occur in October 2011 when codes will be partially frozen until October 2014 [11]. The ICD-10-CM coding system is also hierarchically structured and consists of a core classification of three to seven-digit codes. The first digit of each ICD-10-CM code is designated by a letter that represents the ICD-10-CM chapter. The second and third numeric digits represent the chapter section. A decimal follows the first three digits. Zero to four alphanumeric characters come after the decimal according to the location in the ICD-10-CM hierarchy.