UKCPRS Programme:
                    NHS Dosage Syntax
                         for use with
          NHS dictionary of medicines and devices
                        (NHS dm+d)

                             submitted by
                       Emma Madden on behalf of the
                        UKCPRS Programme Board

                           re-submission in support of
                                 conversion of
                              Conditional Approval

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                 Page 1 of 16
                                       Document History:
                   ISB Requirement Submission for Operational Standard —
                                       NHS Dosage Syntax
                for use with NHS dictionary of medicines and devices (NHS dm+d)

Document Location

This document is only valid on the day it was printed.

Change History
File name: ISAB Submission-RO_DST-v3-00.rtf

     Date         Version                                       Changes
 2004/05/27 –       0.01     UKCPRS Internal drafts with file name format: ISAB
  2004/06/04          -      Submission-RO_MDS-vN-NN.rtf.
                    0.13     Deletion of most redundant ISB guidance matter.
  2004/06/04        0.20     Draft submitted to UKCPRS Project Manager for checking and to ISAB
                             Manager for information.
 2004/06/09 –       0.30     Product name and board members amended in response to comment from
  2004/06/10          –      UKCPRS Project Manager.
                    0.37     UKCPRS Project Manager consulted about remaining details of editing.
                             Completed text, but awaits formal confirmation of Sponsor information (to be
                             included in final v1.00).
  2004/06/10        0.40     Submitted to NHS ISAB Manager for distribution to ISAB for consideration at
                             meeting 2004-07-07, copied to ISB Manager, ISAB Chairman, UKCPRS
                             Project Manager, UKCPRS Senior Supplier.
  2004/06/24        1.00     Completed text, with confirmed Sponsor information, submitted to NHS ISAB
                             Manager for distribution to ISAB, copied to ISB Manager, ISAB Chairman,
                             UKCPRS Project Manager, UKCPRS Senior Supplier. File name amended to
                             better reflect title: ISAB Submission-RO_DST-v1-00.rtf.
  2004/07/14        1.01     Incorporates changes to address ISAB Outcome requested actions Req 1, 2,
      —               -      3, 4, 5, 6, 7, 8 and Draft 1, (2), (3), 8.; and address Disposition points WQ1, 2,
  2004-07-22        1.02     3, 4, 5, 6, 7, 8, 9, (11), 16, VQ1, 2, RQ 2, 3, 4, 5, 6.
                             Circulated and commented in UKCPRS team.
  2004/07/22        2.00     Changes consolidated and submitted to Project Manager for distribution – cc
                             to ISAB managers for information only.
  2004/07/23        2.01     Minor additions and all changes marked in ‘Dark teal‘
  2004/07/26        3.00     Accept all changes to document

         For further copies of this document, contact Stuart Holtom - stuart.holtom@nhsia.nhs.uk

Programme Manager:                 David Tutcher                       david.tutcher@nhsia.nhs.uk
Project Manager:                   Emma Madden                         emma.madden@nhsia.nhs.uk

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                            Page 2 of 16
NHS Information Standards Board          Requirement Submission for Operational Standard      NHS Dose Syntax


        NHS Dosage Syntax
        — for use with the NHS dictionary of medicines and devices (NHS dm+d),
        is Submitted by Emma Madden on behalf of the UKCPRS Programme
        UKCPRS (now NHS dm+d) was approved as a Fundamental Standard in
        March 2003.
        The NHS Dosage Syntax is being implemented and delivered by the NHS
        Information Authority within the context of its UKCPRS Programme. For
        further information please visit the NHS dictionary of medicines and
        devices (dm+d) website: (www.dmd.nhs.uk).
        The content is closely, in areas in which NHS staff and contractors have
        leadership, related to the provisions of HL7 v3.

        The NHS Dosage Syntax is sponsored as follows;
        UKCPRS Programme Sponsor, is:
        Mike Bainbridge mike.bainbridge@npfit.nhs.uk
                      Head of Clinical Application Design,
                      NPfIT Design Authority

        In order to fully communicate information about administration and/or
        supply of a medication to a patient for therapeutic purposes, there must be
        a clear and unambiguous description of both the medicine itself, and the
        prescriber‘s instructions for its use (as distinct from the
        manufacturers/licensees data sheet text).
        The first of these is addressed by the NHS dm+d, which provides standard
        textual descriptions and electronic identifiers for all medicines used in
        healthcare in the realm1.
        The second of these, the ―prescriber‘s instructions for use‖ can be termed
        the ―dosage‖. It is this that is being addressed in this submission. The
        NHS Dosage Syntax will provide a standard grammar (syntax, structure)
        and the supporting vocabularies for use in the structure, to describe and
        unambiguously communicate dosage instructions for medicines, and to
        allow these dosage instructions to be machine readable for electronic
        decision support. The Syntax will therefore deal with concepts such as
        ―how much‖ of the medicine, ―how often‖ to give it, ―where and how‖ to

    Note that, subject to Editorial policy, anything prescribed more than 3 times in a year will be included in dm+d
    as a medicine or device. Recall that the dm+d ISB Requirement submission stated that medicines in this
    context are not necessarily licensed as medicinal products.

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                           Page 3 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

     administer it, and for ―how long‖. (See also the high-level draft model
     In England, the NHS Dosage Syntax will be used in conjunction with the
     dm+d, which will describe the medicinal product itself. However, the
     Syntax is being developed so as to take into account both of the variety of
     ways that a medicinal product may be described, and of international
     requirements and therefore it will not be restricted for use only with the
     dm+d as the medication descriptor. It should be suitable for use in any
     communication of dosage information.
     Thus the NHS Dosage Syntax will therefore be the NHS standard for
     communication of dosage information (instructions for use of medicines),
     for example as specified in the ETP message specifications accepted by
     the NPfIT. It will therefore replace the current practice both for paper and
     electronic communication, which is based on the use of text strings or Latin
     abbreviations and where each clinical information system supplier
     provides their own individual ―proprietary‖ syntax.
     Currently, in a text-based environment (including also text where it is
     generated electronically), representations of dosage instructions do not
     support computational processing and re-use of information across
     applications. Consequently, all dosage instructions require human
     reading and interpretation, and transcription between different systems;
     both of which offer a variety of opportunities for patient-critical error to
     occur. The facility to provide decision support into the dosage process is
     also unavailable.
     Therefore, having a representation of dosage instructions in a format to
     support electronic use is a key requirement to enable, e.g.:
     §      consistent data entry into prescription, dispensing and medication
            administration systems, using the standard syntax and vocabularies;
     §      medication dosage decision support systems such as calculation of
            expected length of duration of supply, dose range alerts;
     §     drug utilisation monitoring, facilitating calculation of supply
           amounts/periods, for robotic dispensing, ward re-stocking,
           compliance monitoring etc.
     It is also fundamental to the building of federated electronic healthcare
     records, such as NHSCRS, since information from all authorised sources
     must be stored in a format that is both reliably retrievable and useful for the
     Many clinical systems managing medicines have local vocabularies to
     produce dosage instructions; however these are non-standard in both
     content and structure.
     In order to reach many of the goals stated above, there is a need for a
     standard representation of dosage instructions to be used across all
     sectors of care. This need for standardisation is also recognised
     internationally, and this project is designed to provide a core part of the
     deliverable of an international initiative in this domain (HL7).
     Improving Patient Safety is at the heart of all of the NHS IT initiatives being
     driven forward by Government. It is estimated that medication errors cost
     the NHS about £500 million per year in additional days spent in hospital.
     The National Patient Safety Agency (NPSA) has emphasised the
     importance of ‗designing solutions that prevent harm‘. Electronic
     prescribing and improved computer prescribing and dispensing systems
     have a vital part to play in reducing medication errors and transcription
     errors by providing clear, unambiguous, timely information.
     These technical developments underpin the overall NHS Quality and

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                    Page 4 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

     Safety Agenda. The NHS Dosage Syntax will contribute to the wider
     benefits to patients and healthcare professionals through the provision of
     consistent textual descriptors and standard electronic codes and structure
     for communicating instructions for use for medicines, in prescribing,
     dispensing and administration leading to safer systems (less prescribing
     and dispensing errors and enhanced decision support).
     Until now there has been no common, standardised syntax for medicines
     dosage. Clinical applications dealing with medicines, such as GP
     systems, Community Pharmacy systems and Hospital Pharmacy systems
     have each developed their own patterns, vocabularies and abbreviations,
     usually based on the ―historic‖ Latin terms to describe dosage. These
     have then been communicated as text strings. This situation does not
     allow interoperability between diverse clinical systems, or allow effective
     decision support through linkage of knowledge to data. The case for
     change is driven at a strategic level by the need to underpin and support
     key national initiatives by providing a unique and unambiguous syntax.
     The NHS Dosage Syntax is required to enable communication of
     information about the prescriber‘s instructions for use of medicinal
     products in the treatment of human patients.
     The NHS Dosage Syntax should cover all domains (primary, secondary,
     tertiary care) in which medications are used, including the core clinical
     specialties that have particular dosage information requirements
     (chemotherapy, child health, anaesthesiology, etc.).
     The ―Dosage Syntax‖ should offer support to the scheduling of medicines
     administration, as well as the description of dosage information.
     A very high-level, and preliminary, model of its scope is given below.
     Point and nature of use:

     Example uses -
     Typical high level uses are as follows:
     §    Point of care in support of decision-making, prescribing, clinical
          documentation, dispensing and administration;
     §    Materials management in support of stock control and costing where
          ―machine readable‖ dosage information is a requirement;
     §      Service management in support of performance improvement and
            adverse drug reaction reporting;
     §      Electronic data interchange in support of safe interoperability
            between computerised information systems.

     Clinical and administrative NHS and DoH users in the context of -
     §    Electronic healthcare records;
     §    Electronic prescribing;
     §      Clinical electronic data interchange;
     §      Decision support;
     §      Stock control;
     §      Costing;
     §      Adverse drug reaction reporting;
     §      Performance management;

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                    Page 5 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard      NHS Dose Syntax

     §      Care delivery systems.
     Community pharmacy users in the context of -
     §  Electronic prescribing;
     §  Clinical electronic data interchange;
     §      Stock control;
     §      Costing.
     Information systems providers in the context of -
     §    Electronic healthcare records;
     §      Electronic prescribing;
     §      Clinical electronic data interchange;
     §      Decision support;
     §      Stock control;
     §      Care delivery systems.
     Current thinking suggests that the vocabularies for NHS Dosage Syntax
     will be distributed with the dm+d; these will therefore be routinely available
     and have an in-built update facility. The Syntax itself will be described
     using appropriate technical documentation. However, once developed, it
     is anticipated that the amount of updating required will be limited, since
     instructions for medicines use do not change dramatically over time. This
     issue will be considered in more depth in Draft standard submission.
     Use scenario:

         Initial High Level Dose
               Syntax Model
                   Feb 2004

                                           How much to be used
                                             [Quantity; Units]

                                                                          In that Where, How to
                                             Where to be used
                                                                                  be used

              A Medicine

                                                                          In that When, For how
                                             When to be used
                                                                              long to be used

                                              Why to be used

                                               Supply Amount
                                              [Quantity; Units]

       Primary Care Dosage Syntax Example Storyboard
       Justine Thyme goes to see her GP, in Tops Surgery in Toytown,

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                          Page 6 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

       because she has a nasty cough and is producing ill smelling green
       phlegm. Dr Indiana Jones, on clinical examination, decides that Justine
       has a bacterial chest infection, meriting treatment with antibiotics.
       He checks Justine‘s electronic medical record ―Risks and Warnings‖
       section for any allergies, but none are present, and he checks with
       Justine herself also, but she has never experienced any medication
       allergies. He therefore decides to use amoxicillin, and moves to the
       ―prescribing‖ application in his clinical system, where his initial action is
       to select Amoxycillin 250mg capsules. He then moves to the dosage
       section, where he is offered a default dosage text that reads ―one
       capsule to be taken 3 times daily, for 5 days‖. He accepts this default
       and the next default, which suggests a supply quantity of 15 capsules.
       The GP clinical system processes the information that Dr Jones has
       entered through the prescribing screen and, using SNOMED-CT, the
       dm+d, and the Dosage Syntax, it runs its decision support, establishes
       both the medication and the dosage is suitable for the patient with this
       condition and then it electronically sends the information for the
       prescription to Justine‘s nominated high street pharmacy.
       Once in town Justine enters the Potions Pharmacy on the High Street
       and presents her ‗electronic prescribing token‘. The dispenser scans her
       token into the pharmacy‘s local system, which already has her
       prescription in it.
       The pharmacy system ―reads‖ the coded information in the prescription
       and automatically builds a complete ‗patient ready‘ dispensing label for
       the item, using the dm+d and the Dosage Syntax. No information
       transcription is required.
       The display and table text for the dosage reads ―Take one capsule three
       times a day, at regularly spaced intervals, for the next five days, until all
       the medication has been used up.‖
       The system also runs a set of clinical checks on the prescription, for
       example, a dose range check, again using the Dosage Syntax to
       ―understand‖ the dosage in a calculable form and compare this to the
       information held in its medicines knowledgebase dose check
       Peter Potion checks the prescription, then, as he hands her the
       medication, checks with Justine that she is both clear about when to take
       the medication and that she has no unanswered questions. Justine then
       leaves the Pharmacy. She takes the medication and her chest infection
       recovers well.

       Secondary Care Dosage Syntax Example Storyboard
       Mr James Bond has been admitted to Good Health Hospital as an
       emergency for pinning of a compound fracture of his left tibia and fibula

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                    Page 7 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

       after a skiing accident. His post-operative pain relief has been
       prescribed by the Registrar who orders Aspav tablets (aspirin and
       papaveretum), two tablets to be administered regularly every 6 hours to
       control the pain adequately with its mixture of NSAID and analgesic.
       Aspav Tablets are a ―non-stock‖ item on James‘ ward, so an alert is
       generated by the clinical system for pharmacy, which notes that it was
       the Registrar ordering the medication, and therefore a non-stock item
       can be supplied. Using the dosage information from the prescription, an
       initial 5 day supply of 40 tablets is dispensed and sent up to the
       Orthopaedic ward.
       The nursing system notes the receipt of the Aspav tablets, and the
       dosage instructions of the prescription. The next drug round is due at
       12.00hrs, which the application has calculated is appropriate for
       administration of a ―6 hourly‖ administration regimen. Therefore, the first
       administration of James‘ Aspav tablets is shown on the administration
       screen for this round, and will then be displayed on the subsequent
       appropriate screens for that 6 hourly regimen, until it is discontinued.
       The Pharmacy system, that could calculate from the dosage, the
       expected duration of the supply quantity that they issued, will ―check‖ in
       four days‘ time whether the medication is still current, in which case
       further supplies of the medication will be needed for ongoing use.
     Performance characteristics:
     In order to be a trusted clinical tool the NHS Dosage Syntax must be
     It must deliver the elements and structures required to communicate
     dosage information unambiguously electronically between systems and
     into and out of the Electronic Health Record, and to allow electronic
     decision support to process this dosage information for the purposes of
     safety and suitability checking. It must be applicable for dosage
     information in all domains of medicinal product use (primary, secondary
     and specialist care).
     It is to be expected that 95% of the examples tested be messaged
     correctly and consistently by the model. The remaining 5% will take longer
     to resolve and will be managed by retaining some support for narrative
     dosage in the interim.
     One should note that the quantification of percent coded to equate to
     success is however, difficult to define. To arbitrarily state 95% of all
     examples must ―work‖ is not necessarily a useful exercise, as the easier
     95% will be easier to code and by definition these will be the dose
     instructions less likely to cause issue. It is the more complicated dose
     instructions that will be more prone to produce error and thus more
     important to code correctly. If these are the 5% that fail the test process
     then even though the 95% threshold would imply success, the workstream
     objectives stated above cannot be seen to have been achieved

     Out of scope:
     The NHS Dosage Syntax will not include description of the instructions for
     use for medicinal devices, or therapies other than medicinal products (e.g.
     radiotherapy dosages).

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                    Page 8 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard     NHS Dose Syntax

     The NHS Dosage Syntax will not ―mandate‖ the use of the core descriptive
     concepts from the standard supporting vocabularies in all clinical systems;
     some ―synonymy‖ of terms will be allowed to support two particular
     business needs:
     §       language translation; e.g. dosage entered using a Welsh vocabulary
             in a clinical system is communicated electronically and then
             displayed in English in the pharmacy system;
     §       context translation; e.g. dosage entered using ―clinician
             understandable‖ vocabulary (likely to be the one used for the core
             descriptive concepts) is communicated electronically and then
             displayed using ―Patient Friendly‖ descriptors in the pharmacy
             labelling system and on the printed dispensing label.

     Strategic Fit
     The availability of ‗UKCPRS‘ (now NHS dm+d) and hence the NHS
     Dosage Syntax is assumed by NPfIT ICRS-OBS2-2
     mmeArticle/fs/en?CONTENT_ID=4071618&chk=FzV2Cm ) which states:

       113 – Prescribing and pharmacy
       Prescribing and administering drugs to patients is a key care process. Both processes, if
       inadequately informed, can also cause serious risks to patient safety. This module
       describes the core functionality required to allow and support the safe prescribing of
       drugs by Clinicians, as well as assisting in managing the dispensing and administration
       of drugs (mainly in the hospital setting), and monitoring and presenting each patient's
       drug history and compliance.
       The scope of this module includes all prescribing and drug use across the NHS: in
       Primary Care; in the Acute Care sector; and by community practitioners, as well as
       provision of drugs in the community. …
       Other Requirements
       A national drug database covering all sectors - The service shall comply with the
       UKCPRS (which will be a component of SNOMED CT).
       790 – Standards
       The purpose of this module is to document the standards that shall be used in relation to
       the NPFIT. These standards have been arrived at through discussion with NDA, NHSIA,
       STEP, ISB and third parties. This document has been developed following close
       consideration of STEP, ISB and e-GIF and aims, where possible, to strategically align
       with the standards certified and documented by the above bodies. The requirements
       detailed in this module reflect the need for LSPs and the ICRS NASP to adhere to
       current legislation and observe standards as they evolve and emerge. This will include
       being able to embrace new legislation and standards and upgrade existing standards
       without undue delay as required by the Authority.

       Detailed Requirements
       All new systems shall support the UKCPRS standard.
       All existing systems should support UKCPRS.

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                       Page 9 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard     NHS Dose Syntax

       The Overview text in Section 790 of the OBS (see above) explicitly requires integration
       of the dm+d into the NHS Business Architecture as it is understood as being critical to
       the safe operation of the ICRS. These standards have been taken forward in the
       contracts signed with NASP and LSP consortia.
       In making the submission of the Requirement for an Operational
       standard for NHS dm+d in January 2004 it was stated by Tim Jones
       ―I would have expected that the DA/TO could not have made a more definite statement
       of support than having put it into the OBS and that a further statement is unnecessary.
       and by Jeremy Thorp (2004-01-30):
       ―I am writing on behalf of the Design Authority to confirm our support for this work. The
       submission already describes how the requirement (expressed using the former title of
       UKCPRS) has been incorporated into NHS Care Record Services contracts. It also
       describes how dm+d forms an important component of SNOMED CT - together these
       will provide the clinical language foundation for the future.

     Operational Fit
     In all instances the NHS Dosage Syntax will be presented in a NHS dm+d
     context that is compatible with that already used by clinical applications in
     a manner familiar to the users. Most clinical applications use some form of
     proprietary dosage syntax, therefore implementation of a standard syntax
     and supporting vocabularies will not be a totally new concept for
     developers or users of applications to manage.
     It will also be supplied with information on how to use it with the HL7 V3
     messaging structures that are required for all National Programme
     communications about medicines, including their ―instructions for use‖ or
     dosage information.
     Similarly, confidentiality, security, legal and professional issues are not
     expected to change materially; if anything the improved consistency of
     communication could be expected to improve legal and professional
     liability matters.
     Strengths and Weaknesses
     If implemented as described above then the strengths, benefits and
     weaknesses are as follows:
     Strengths when implemented:
     §    Provides a single system of describing medicines dosage;
     §    Provides the whole NHS (in hospitals, primary care and the
          community) with a means of sharing descriptions of medicines
     Benefits when implemented:
     §   Facilitates structured description of medicines dosage such that the
         granularity of description currently used in free-text communication is
         fully supported;
     §        Enables reduction of medication errors and transcription errors by
              providing clear, unambiguous, timely medicines dosage information;
     §        Enables point of care support for decision-making, prescribing,
              clinical documentation, dispensing and administration;
     §        Enables electronic data interchange in support of safe medicines

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                      Page 10 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

            dosage interoperability between computerised information systems;
     §      Enables materials management in support of stock control and
     §      Enables service management in support of                              performance
            improvement and adverse drug reaction reporting.
     A number of benefits of having a standard dosage representation available
     can therefore be expected:
     §    Standard representation of medicines information in health records;
     §      A reduction in errors from interpretation of dosage information; all
            clinicians will become familiar with the standard, full documentation
            will be available to support any queries;
     §      A reduction in errors from transcription and calculation of dosage
            information; systems will be able to communicate seamlessly,
            therefore transcription should not be required; this includes
            communication from clinical application to administration devices
            and systems such as infusion pumps etc.
     §      A reduction in clinical errors in the medication process as decision
            support can perform checks on dosage information;
     §      Efficiency improvements in medication processes due to seamless
            information transfer.
     Weaknesses when implemented:
     None identified if implemented as planned.
     Except for availability of medication information when a social services
     professional has appropriate clearance to access health records there is
     no anticipated use for the NHS Dosage Syntax in the Social Care sector.

     §      Software Development Effort Higher than Expected:
            Software development has a propensity to require more effort than
     §      Test Case Examples Inadequate:
            This can be mitigated by widely circulating a list of categories of
            dosage information, and soliciting ―difficult cases‖. This may be
            through the NHS-IA UKCPRS programme website but may also
            involve the professional literature.
     §      Timescales, Availability and Operational Requirements:
            The requirements for this work are urgent, since a significant amount
            of Phase 1 implementation in the National Programme requires this
            to be in place.
            Due to other pressures from other projects, reasonable staff
            availability cannot be taken as a given. In the Project Plan, the
            availability is generally minimised in an attempt to give realistic
            delivery timescales.

     Risks when not implemented:
     Note that these are shared with the same risks for dm+d itself.
     §    No common, standardised vocabulary for clinical products;
     §    No interoperability between clinical systems;

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                   Page 11 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

     §      No consistent decision support possible;
     §      No exchange of comparable information on medicines and devices;
     §      No consistent reduction in medication errors and transcription errors
            by providing clear, unambiguous, timely information;
     §      No widespread support of materials management in stock control
            and costing;
     §      No common service management in support of performance
            improvement and adverse drug reaction reporting possible.
     Issues when implemented:
     §      Migration from existing fragmented systems could be hampered by
            commercial will, cost, complexity and availability issues. These have
            the following mitigation aspects.
           1. Commercial will
              a The use of the (UKCPRS) NHS dm+d, in total, is mandated
              by the NSP and LSP contracts for ICRS service provision;
              b Costs of system integration will be reduced by availability of a
              common standard NHS Dosage Syntax.
           2. Cost
              a The NHS dm+d and the NHS Dosage Syntax is freely
              available to registered (free) systems suppliers, service providers
              and users;
              b Costs of system integration will be reduced by availability of a
              common standard NHS Dosage Syntax.
           3. Complexity
              a The complexity of the NHS Dosage Syntax is no greater than
              that the variety of existing ad hoc systems and indeed the
              selection methods are directly comparable with those in current
              use – even to the number of ‗levels‘ of granularity;
              b No supplier/ service-provider maintenance (other than
              enabling pass-through updating) is required. By having the NHS
              Dosage Syntax standard, costly and risky mapping of proprietary
              systems between each other is avoided.
           4. Availability
              The NHS Dosage Syntax structure, vocabulary and technical
              documentation will be freely available via the NHS dm+d website.
              Vocabulary will also be available from standard terminology
     §      Use (widely in both primary and secondary care) by clinical
            professionals could be perceived as ‗slow‘ when compared with
            current hand-written free-text documentation (but no worse than with
            current use of proprietary computerised systems). The mitigation for
            this is that ‗whole-task‘ (selection, prescription, dispensing,
            administration, contraindication checking and logistics) use of the
            structured NHS Dosage Syntax requires less interpretation and is
            hence prone to error – reducing both risks of harm to patients and
            direct and indirect costs to the NHS.

     Existing work by the NHS IA, the literature in this area, (both in the UK and
     internationally (e.g. ENV 13697, NCPDP, G-Standard)) has been reviewed
     and while previous the work done is of great interest, no work has been
     identified that meets all the requirements of this project.

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                   Page 12 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

       Analysis of dosage syntax in existing clinical systems, such as in primary
       care and community pharmacies revealed no consistency or
       standardisation. The majority are text format, even if using ―codes or
       abbreviations‖ (e.g. t.d.s).
       During the Literary Review stage existing standards were considered and
       rejected primarily because of their development for mainly Primary Care
       requirements, making them not suitable for all Secondary Care
       Both the US NCPDP Script Standard and the Dutch G-Standaard are also
       primary care based dosage descriptions.
       ENV 13607, ―Health informatics - Messages for the exchange of
       information on medicine prescriptions‖ which includes structured dosage
       information, was reviewed. Regrettably it was concluded that as it was
       also developed for mainly for Primary Care and therefore does not meet
       Secondary care requirements. Of particular concern was the lack of
       supporting vocabulary accompanying ENV 13607, therefore it was unclear
       ―how‖ the structure proposed by the standard might be implemented in
       practice, particularly for more ―complicated‖ phrases.
       The NHS Dosage Syntax is based upon the provisions of NHS dm+d and
       is linked to SNOMED CT and integrated with HL7 v3.
       Thus, there is no known national or international alternative to the
       proposed UKCPRS NHS Dosage Syntax approach.2
       Since all messaging of medication information will be using HL7 V3, and it
       will be this messaging that will provide information into the NHSCRS, there
       is a functional requirement to ensure that the structure and vocabulary
       map into the V3 Medication messaging model.
       The mapping of the elements of the dosage syntax model to the
       appropriate structures in the V3 Domain Message Information Model
       (DMIM) is therefore a requirement. This will be a ―field to field‖ and
       ―definition to definition‖ mapping. It is envisaged that this will be delivered
       in a similar manner to the HL7 V3 ballot package and consist of a ―Dosage
       DMIM‖ (a specific subset from the Pharmacy DMIM) with textual
       walk-through and supporting vocabulary tables, and one or more RMIMs
       (Refined Message Information Models) and schemas for specific example
       The dm+d is related to (but not dependent on) the SNOMED-CT Core, and
       the provisions of the HL7 v3 Reference Information Model, as contributed
       by HL7-UK and the HL7 Pharmacy Special Interest Group.
       As illustrated in the section on ‗Strategic Fit‘ the establishment of a
       clinically safe integrated care record service (ICRS) is dependent on the
       ability of contributing applications to populate record components from a
       single unambiguous terminological source.

       The identified interdependencies do not impose critical path limitations
       upon development of the NHS Dosage Syntax; so tight integration of time
       scales is not an issue.
       The core deliverables of the NHS Dosage Syntax will consist of:

    Literature Review Document can be made available to ISB if required.

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                   Page 13 of 16
NHS Information Standards Board        Requirement Submission for Operational Standard        NHS Dose Syntax

     §      an information model describing dosage information;
     §     this is then translated into a physical deliverable;
     §     that is initially populated with suitable vocabularies.
     These are to be supported by documentation that includes formal
     definitions and concept population policy (―Editorial Policy‖).
     Existing functionality of systems migrating to NHS Dosage Syntax will be
     reviewed prior to Draft Standard submission. A decision has been made
     that legacy data will not be translated into the NHS Dosage Syntax due to
     the number of varying methods of noting dosage, which would make it
     clinically unsafe to do so.
     Once NHS Dosage Syntax is introduced for ETP and PSIS records, all
     existing proprietary and informal dose syntaxes will be superseded.
     The deliverables can then be validated against the needs and
     The budget for this work has been identified within UKCPRS Budget
     2004/2005, which will adequately cover the development of this standard.
     The Pharmacy Team at NHS IA will undertake any maintenance under
     funding arrangements already in place through the business case for the
     maintenance of the dm+d.
     The proposed (and subject to refinement) test plan is as follows:
       The testing process should investigate both the model and the vocabulary for fitness for
       Testing should be conducted in two initial stages, alpha and beta, with some
       development of testing tools in between.
       The alpha testing will involve the collection of a relatively small number of sample
       dosage instructions to use in building the model and initial population of the vocabulary.
       A structure and vocabulary that can support these examples will then exist.
       From this, and having completed the mapping of the structure and vocabulary to the HL7
       V3 messaging, an information entry interface should be developed. This will allow entry
       of dosage data into a piece of test software, which will use the structure and vocabulary
       and ―translate‖ the information through into the V3 schema (xsd). This can be ―sent‖ as if
       it were a message, to a second piece of test software, which receives the information,
       then displays it back as information on screen (or writes it to a results sheet). This is the
       equivalent of writing information to an EHR or sending it to another medication system.
       The input information and the output information must then be compared and analysed
       by a domain expert, external to the project team.

       This process can be shown diagrammatically as follows:

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                          Page 14 of 16
NHS Information Standards Board          Requirement Submission for Operational Standard      NHS Dose Syntax

          Dosage Model and
           Syntax Testing                          Model and
          Process Diagram                          Vocabulary

                       Data Entry   Web-based       HL7 V3         Translation    Display    Text Data Out
        Text Data In                                                             Interface
                        Interface    Software                       Software

                                                   Domain Expert

       The beta testing will therefore involve taking a larger sample of dosage information and
       putting it through this process, and analysing the results obtained.
       All of this testing process should be web based to enable widespread access and
       The results of initial testing should be available in a format of ―text in‖ and ―text out‖ to
       allow comparison by a domain expert. An example of input and output might be ―Give
       exotocillin 400micrograms/kg/hour over 6 hours by Intravenous infusion‖ and
       ―Exotocillin - 400microgram per kg per hour - for 6 hours duration - by infusion
       intravenous‖; these would be judged to be clinically equivalent, and therefore a
       successful use of the model.
       To avoid bias in interpretation of the results, a domain expert external to the project (a
       member of the NHS-IA Pharmacy authoring team) will undertake the analysis of the
       results of the beta testing.
       The analysis will involve comparison of input and output text strings, and judging
       whether they are semantically identical in content and meaning.
       If the results of the analysis are positive the model and vocabulary are judged initially fit
       for purpose, and the project board will decide what if any next steps are required. By
       using a web-based data entry interface, it will be possible to offer the package for wider
       (beta) testing by the clinical community, with the resultant feedback enriching the project
       If the results of the analysis reveal deficiencies in the model and vocabulary further
       development of the model to accommodate the areas of deficiency can be undertaken.
     It is not anticipated that the introduction of NHS Dosage Syntax will raise
     new training or human and behavioural issues but because it will, at the
     point of use, replace an existing ad hoc analogue of the new syntax, a risk
     assessment will be undertaken.
     The importance of maintaining the accuracy of the prime resource and
     ensuring end-to-end audit to assure and maintain accurate and full
     implementation has been considered and will be addressed when the
     maintenance plans are drawn up prior to the Draft Standard submission.
     Depending on the outcome of this application for approval of a
     Requirement, and within the scope of the UKCPRS Strategic Framework
     Standard already approved, a Draft Standard submission of NHS Dosage
     Syntax as an Operational Reference Source Standard is anticipated in Q3


3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                            Page 15 of 16
NHS Information Standards Board       Requirement Submission for Operational Standard   NHS Dose Syntax

     In addition to the support of the DoH Information Policy Unit and the
     Prescription Pricing Authority, the UKCPRS and resulting NHS dm+d
     (including NHS Dosage Syntax), have the active support of the following:
     Senior Suppliers
     Paul Frosdick,               Head of Professional Networks,
                                  NHS Information Authority
     Christine Dalton,            Director of Pharmaceutical Policy and Services,
                                  NHS Prescription Pricing Authority
     Senior Users
     Dr. Colin Price,             Assistant Director Healthcare Networks,
                                  NHS Information Authority
     Nick Scholte,                Chief Executive Officer,
                                  NHS Prescription Pricing Authority
     Ian Arrowsmith               Consultant - Health Information Design,
                                  NPfIT Design Authority
     Dr Felicity Harvey           Head of Medicines, Pharmacy & Industry Group,
                                  Department of Health
     These individuals are all members of the Programme Board and as such
     ensure that the Programme is aligned with the requirements of the ICRS
     The Senior Users, as UKCPRS Board members, represent the views of
     the primary users of this standard, i.e. the clinical and administrative NHS
     and DH staff and system providers. Editorial Board members also
     represent the interests of the Royal Colleges.
     Other sources of support include;
     Medicines and Healthcare Product Regulatory Authority – for recording
     information on product safety and adverse events;
     National Patient Safety Agency – for recording information on medication
     errors and mishaps, and to minimise errors in clinical practice;
     Purchasing and Supply Agency – to move forward the eCommerce
     FDB (Decision Support Supplier to BT NASP) have volunteered their
     support and will be involved throughout the development of the NHS
     Dosage Syntax. In addition the NHS Dosage Syntax is represented at and
     receives feedback from NPfIT Terminology Meetings (chaired by Mike
     Cooke) and at a sub group - the Medicines Terminology Sub-Group
     Meetings (chaired by Mike Bainbridge). The NASP and LSPs are actively
     represented at both these meetings.

3552fab7-bd6a-474c-8280-e2ad06981c53.rtf                                                   Page 16 of 16

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