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

1df5ba15-2fc9-426b-9fcd-599451577fa2.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

1df5ba15-2fc9-426b-9fcd-599451577fa2.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.

1df5ba15-2fc9-426b-9fcd-599451577fa2.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

1df5ba15-2fc9-426b-9fcd-599451577fa2.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;

1df5ba15-2fc9-426b-9fcd-599451577fa2.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,

1df5ba15-2fc9-426b-9fcd-599451577fa2.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

1df5ba15-2fc9-426b-9fcd-599451577fa2.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).

1df5ba15-2fc9-426b-9fcd-599451577fa2.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.

1df5ba15-2fc9-426b-9fcd-599451577fa2.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

1df5ba15-2fc9-426b-9fcd-599451577fa2.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;

1df5ba15-2fc9-426b-9fcd-599451577fa2.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.

1df5ba15-2fc9-426b-9fcd-599451577fa2.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.

1df5ba15-2fc9-426b-9fcd-599451577fa2.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:

1df5ba15-2fc9-426b-9fcd-599451577fa2.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


1df5ba15-2fc9-426b-9fcd-599451577fa2.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.

1df5ba15-2fc9-426b-9fcd-599451577fa2.rtf                                                    Page 16 of 16

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