Fig. 1 Data exchange using the markup language
1. What is the MML?
The MML is the specification for optimum exchange of clinical data between different clinical institutions. The database can be considered to be a kind of table. Each institution uses a uniquely defined table. Therefore, the exchange of a simple data set such as that includes address, name, diagnosis, etc. may lead to different sequence of data between institutions. If such data is transmitted as is, the data sequence changes. To allow for proper exchange, the database for all clinical systems should be integrated into the same structure. However this is impractical as all systems currently operating throughout the country world have to be rewritten. The MML (Medical Markup Language) is a standard format for data exchange which we have studied for the purpose above. The latest version MML has been developed via XML technology. To ensure that the specification is available for multiple electronic medical chart systems, the data is converted into MML documents (MML instances) for data exchange with other institutions. (Fig. 1) The institution receiving the data converts the MML data into its own format for mapping to the database. This allows for the data exchange for clinical institutions throughout the country while maintaining the uniqueness of each institution. Each system is designed by each vendor on a competitive basis. The principle of competition will lead to the development of a better system of operation.
Fig. 1 Data exchange using the markup language
Another advantage of using MML is that each system only has to prepare one interface for the standard format. (Fig. 2) If a different interface for data exchange between different systems had to be prepared, the number of interfaces would be numerous. It would be impossible to prepare such a number of interfaces.
The MML idea was first born at the Seagaia Meeting (Annual Meeting of The Japan Association for Medical Informatics "Electronic Health Record Research Group") held in Miyazaki in May, 1995. At that time, the method using SGML was reviewed. The data exchange method with the SGML (Standard Generalized Markup Language) was taken over by the Research Group (consisting of members from the Electronic Health Record Research Group) of the Electronic Medical Chart Development Project of the Ministry of Health and Welfare which started in 1996. Currently, an MML working group from the Electronic Health Record Research Group is carrying out ongoing development of the method.MML uses a description method similar to that of HTML (Hyper Text Markup Language) for the creation of Internet web pages. In general, this kind of description method is called a "markup language". HTML tags contain information such as <center>, <H1>, <p> (centering, header 1, paragraph, respectively) for layout of characters. It is easy to send clinical information in HTML format. However layout of the data must be acceptable to the end user visually.
If the following HTML information
<left>James Bond</left><p>
<left>Gastric cancer</left><p>
is sent to another institution, the data is displayed with left aligned as shown below.
James Bond
Gastric cancer
This information is easily recognizable by human as name and diagnosis. In order to be recognized by a computer and to map the diagnosis and the name in a database, for processing purposes, it is better to use tags with medical terms like:
<name>James Bond</name>
<diagnosis>Gastric cancer</diagnosis>
The technology for transmission of medical information with tags like <name> or <diagnosis> in the example above is the MML. We have reviewed the logical structure of the medical chart and detailed the medical categories (diagnosis, symptom, etc.) used in the charts. We then defined such categories as tags with a medical meaning. With these tags, the DTD (Document Type Definition) may be formed using the SGML. The DTD is a definition format for the SGML document structure or tags. The MML is equivalent to the DTD of the SGML. When the data is exchanged between medical facilities, medical information can be properly sent if converted into an MML document (the SGML document in a broad sense). From version 2.2.1, the MML is described in the XML (eXtensible Markup Language) format which is a language developed from the SGML. Considering that medical information is mainly exchanged between databases, XML technology, which is well-suited to databases, is employed. The current tendency world wide is the use of XML as a standard technology for data exchange. We are proud that we have taken the logical choice.
2. MML latest version
The latest version 2.2.1 is based on previous versions using SGML. SGML has now completely changed to XML. Changes from the previous versions are as follows:
MML Part 1
1) The structure was separated (into modules) with NameSpaces. This has allowed development of individual modules for each medical department. In upgrading to a newer version, the effect on the entire program has been minimized.
- Modules for repeated structures
- Modules of sections that can be separated for terminology
2) Addition of surgery record module
3) Details of clinical summary module
MML Part 2
We have defined the draft related to the electronic message including search, addition and deletion.
With the above changes, the MML is separated into the frame structure (white block) and the modules (blue block) used in the structure as shown below. In actual operation, modules (sub DTD) are used as necessary. The MML is responsible for the range of modules, up to and including those defined here. Other functions may be added in the future according to requests from users.
Fig. 3 Basic structure of MML 2.2.1
3. What does MML do?
MML has been prepared as the specification for exchange of clinical information. With MML, the following applications are available.
3.1 Medical data exchange between different systems
It is not an easy task to exchange data for electronic medical charts that have different database structures. Usually, a compatible interface is prepared for the specified counterpart. However, this interface is not useful for data exchange with other medical institutions. When each system has installed the MML interface and then sends information in the MML format, the MML interface analyzes this data and stores the data into the particular database. Then, medical staff can refer to the data from their own electronic medical chart system that the staff has been accustomed to.
3.2 Data backup in the facility (electronic medical
chart for long-term storage)
The electronic medical chart system stores large quantities of data such as order information, medical information, etc. In addition to the clinical data, it includes various data (flags, history records, etc.) for operation. The information is not limited to clinical data only. As a result, it is difficult to store the data for a long period time. Therefore, the data is separated into two categories: active data, such as reservation information that may be changed, and fixed data that does not have to be changed. The fixed data is described in the MML format and is stored in a separate database.This allows efficient long-term storage of clinical data. (Fig. 4) This is very useful if the system vendor changes in the future. When the MML interface is installed on a new vendor's system, the clinical data can be described on the new electronic medical chart system from the long-term database. Miyazaki Medical College is scheduled to operate this long-term storage medical database in the year 2000. This database has an MML interface; it is not necessary to develop a special method for data exchange with other systems.
3.3 Common database for local medical institutions
Ideal practice would be that each medical institution in the local area would install the MML interface on the medical chart system for data exchange. Problems still exist; inadequate internet infrastructure, economical problems for continued access, and difficulty of maintaining a fully-fledged electronic medical chart system for a small clinical facility. In fact, it is difficult for each institution to install the MML. Therefore, the medical institutions in the local area will collectively prepare the MML-compliant database for common use. Each medical institution should send the MML document to this database. In this way, the medical institutions and patients who have memberships can share the data. The system at each medical institution may be different, but each system must install the MML interface. Private general practitioners or patients who do not have a special medical chart system can gain access to the WWW interface on the common database via a normal PC and see medical charts via a WWW browser.This experiment started in 1998 in Miyazaki prefecture. 9 medical institutions including 3 prefectural hospitals, the university hospital and clinics have already gained access to the database. These medical institutions are interconnected via the VPN (Virtual Private Network) for exchange of information in a safe environment.
3.4 Remote backup and certification of authenticity clinical data
The method described in the previous section also functions as a remote backup of important data for medical institutions. When the common database is managed by a reliable third-party institution, authenticity of clinical data (legal proof that the data has not been altered) can be certified. Such legal proof is, therefore, convincing enough at this time. In the near future, a "medical data bank" that trades medical information, not just a provider, may appear on the market.
4. Reference information: for further reading
1) MML 2.2.1 Standardhttp://www.seagaia.org/MML_E1028.pdf2) Seagaia Meeting homepage (latest MML information, Japanese-written page)
http://www.seagaia.org/3) MML contact address
E-mail: sg-office@seagaia.org4) Seagaia Mailing list: seagaia-ml@seagaia.org
Electronic medical chart research group/The Seagaia Meeting is managing the mailing list for popularization of the electronic medical chart and further information. Anyone can join this main list. If you are interested, please register your address.
Contact for mailing list registration: sg-office@seagaia.org5) Past materials for MML development
Report of Electronic Medical Chart Development Structure Technology Core Team of the Ministry of Health and Welfare/ April 12, 1996 (Japanese-written document)
http://www.miyazaki-med.ac.jp/medinfo/SGmeeting/document/health/health_00.htmlMML ver. 1.0 _3 (Electronic Health Record Research Group, Japan Association for Medical Informatics, Japanese-written document), 1997
http://www.miyazaki-med.ac.jp/medinfo/SGmeeting/document/SG97/02Ohe/ohe.htmlStandardization of Exchange Procedures of Clinical Information, and an Experiment of Clinical Data Exchange Using Medical Markup Language (MML), JJMI; 17(Suppl.): 203-207, 1997
http://www.miyazaki-med.ac.jp/jjmi/17_3s/17_3s_05.html
Medical Markup Language (MML) - An SGML DTD for Medical Records Information, 1998
http://www.miyazaki-med.ac.jp/199805MMLFrance/
MML Version 2.0 (MML Working Group, Electronic Health Record Research Group, Japan Association for Medical Informatics, Japanese-written document), 1999
http://www.miyazaki-med.ac.jp/medinfo/SGmeeting/SGmeeting99/doc/MMLV2/MML_v2.htmlMML 2.0 Standard (Japanese-written document), 1999
http://www.miyazaki-med.ac.jp/mmlv2/index.htm
Epilogue
The above provides a general description of MML. Hopefully, the XML technology represented by MML will become ever more popular and that adequate medical services will be provided to all patients. (Written by: Hiroyuki Yoshihara, MML-WG, Electronic Health Record Research Group, Nov. 15, 1999)