Dose to Text Translation
This section details the logic required for a system to generate a suitable, clinically safe, complete medication plus dosage string from the coded structures.
Research References
This guidance is aligned with;
Common User Interface (CUI) Medications line recommendations, England, May 2010
National guidelines for on screen display of medicines information, Australia, December 2017
Common Principles
The following applies to the presentation of any component part of the dosage instruction;
Always express units of measure using the full description, e.g.
milligram
notmg
.Important: The above principal does not apply to units of measure as part of pre-coordinated dm+d concept descriptions, e.g.
Ramipril 5mg capsules
.Always express a time-based unit of measure in the plural when applicable, e.g.
2 hour
becomes2 hours
.Do not express other units of measure in the plural as this introduces complications with units such as
microgram per millilitre
ormicrogram per kilogram per hour
.Where multiple statements are allowed, e.g. when or event structures, then separate each statement with a comma plus whitespace. Replace the last comma separating the final two statements with the word " and ", e.g.
on Monday, Wednesday and Friday
.
Component Part Separator
In most cases, each component part of the medication instruction is separated by space-dash-space, e.g. " - ".
Oxytetracycline 250mg tablets
-
1 tablet-
4 times a day-
oralOxytetracycline
-
250 milligram-
4 times a day-
oral
Exceptions are as follows:
Use a single whitespace after a
method
, e.g. Apply...Use a single whitespace to separate between a
dayOfWeek
andtimeOfDay
, e.g. on Monday at 10:30
Logical Display Order
The order in which the structures within the Resouce should be listed.
- Medication Name
- Medication Form (if not implied within a VMP/AMP name)
- Trade Family Name (if not implied within an AMP name)
Then for each dosageInstruction
;
- method
- doseAndRate.doseQuantity / .doseRange
- doseAndRate.rateRatio / .rateQuantity / .rateRange
- duration, durationMax
- frequency, frequencyMax, period and periodMax
- offset, when(s)
- dayOfWeek(s)
- timeOfDay(s)
- route
- site
- asNeededCodeableConcept / asNeeded
- boundsDuration / boundsRange
- count, countMax
- event(s)
- maxDosePerPeriod / maxDosePerAdministration / maxDosePerLifetime
- additionalInstruction(s)
- patientInstruction
Translation Logic: Medication
Medication name
CUI recommends the medication name is formatted in bold. The text narrative supports XHTML mark-up therefore the medication name could be marked-up within <b> ... </b>
HTML tags.
If using a VTM concept, the name will just be the name of the VTM.
- Paracetamol
If using a VMP concept the name will include the strength and form. The unit of measure associated with the strength may use an abbreviated term as this is part of the dm+d standard.
- Paracetamol 1g tablets
If using an AMP concept the name will be the AMP description which includes the supplier name. The unit of measure associated with the strength may use an abbreviated term as this is part of the dm+d standard.
- Paracetamol 1g tablets (Dawa Ltd)
Medication form
If the form is not implied within a VMP or AMP name, then no additional formatting is required.
Trade family name
Although not supported yet within FHIR profiled resources, when available, format into UPPER case.
- ZOMORPH
Translation Logic: Dosage
Element: method
No additional formatting required.
Element: doseAndRate.doseQuantity
Express as:
{quantity} {units}
50 milligram
2 tablets
Element: doseAndRate.doseRange
Express as:
{low} to {high} {high_units}
- 20 to 40 millilitre
Where only a doseRange.high
is defined, express as:
up to {high} {high_units}
- up to 40 millilitre
doseRange
with only a low
value and an omitted high
value.
Element: doseAndRate.rateRatio
When the denominator value is 1 (one) express a rateRatio
as:
at a rate of {numerator_value} per {denominator_unit}
Otherwise express as:
at a rate of {numerator_value} every {denominator_value} {denominator_unit}
Express the time-based units in plural when required.
at a rate of 30 millitre per hour
at a rate of 30 millitre every 2 hours
Element: doseAndRate.rateRange
Express as:
at a rate of {low_value} to {high_value} {high_units}
- at a rate of 1 to 2 liter per minute
Element: doseAndRate.rateQuantity
Express as:
at a rate of {value} {units}
- at a rate of 1 microgram per kilogram per hour
microgram per kilogram per hour
.
Elements: duration
/ durationMax
Express a duration
as:
over {value} {units}.
Express the time-based units in plural when required.
Where a durationMax
is defined, append with
(maximum {max_value} {max_units}).
over 8 hours
over 4 hours (maximum 6 hours)
Elements: frequency
/ frequencyMax
/ period
/ periodMax
Express the combination of frequency
and period
as:
{frequency} times every {period_value} {period_unit}`
- 3 times every 8 hours
Where a frequencyMax
is defined, express as:
{frequency} to {frequencyMax} times every {period_value} {period_unit}
- 2 to 3 times every 8 hours
Where a periodMax
is defined, express as:
{frequency} times every {period_value} to {periodMax_value} {period_unit}
- 3 times every 6 to 8 hours
Where both frequencyMax
and periodMax
are defined, express as:
{frequency} to {frequencyMax} times every {period_value} to {periodMax_value} {period_unit}
2 to 3 times every 6 to 8 hours
Where a frequencyMax
is defined without a frequency
then express as:
up to {frequencyMax} times
up to 3 times a day
up to 4 times every 8 hours
up to 6 times every 3 to 4 weeks
frequency
and frequencyMax
when either a period
or periodMax
is present is allowed as per cardinality rules but should be prevented in practice as does not result in a logical timing instruction.
Special Cases
When period
is 1 (one) without a frequency
, express as:
daily, weekly, monthly, or annually depending on the
periodUnit
.
In theory, the periodUnit
could be s
(seconds) or min
(minutes); however, the use of these without an associated frequency
is illogical.
When frequency
is 1 (one) without a period
, express as:
once
When frequency
is 2 (two) defined without a period
, express as:
twice
When frequency
is greater than 2 (two) and defined without a period
, express as:
{frequency} times
- 3 times
When frequency
and period
are both 1 (one) express as:
once a {period_unit}.
- once a week
When frequency
is 1 (one) and period
is greater than 1 (one) express as:
every {period_value} {period_unit}
or
every {period_value} to {periodMax_value} {period_unit}
every 8 hours
every 6 to 8 hours
When frequency
is 2 (two) and period
is 1 (one) express as:
twice a {unit}.
- twice a day
When frequency
is greater than 2 (two) and period
is 1 (one) express as:
{frequency} times a {unit}.
- 4 times a day
When frequency
is 2 (two) and period
is greater than 1 (one) express as:
twice every {period_value} {period_unit}
or
twice every {period_value} to {periodMax_value} {period_unit}
twice every 8 hours
twice every 6 to 8 hours
Elements: offset
/ when
Any offset
will be defined as a number of minutes. If this equates to a whole number of hours or days then express as the number of hours (=60 minutes) or days (=1440 minutes). Use the singular or plural expression of time when required. Separate multiple statements with a comma and use the word "and
" to separate the final two statements.
The FHIR event timing value-set used for when
should have descriptions modified to make them more human readable.
Remove the text "event occurs [offset]" and "(from the Latin...)" from the descriptions.
Simplify the following value-set definitions;
- Display: "After Sleep" - Use definition "once asleep"
- Display: "HS" - Use definition "before sleep"
- Display: "WAKE" - Use definition "upon waking"
- Display: "C" - Use Definition "at a meal"
- Display: "CM" - Use Definition "at breakfast"
- Display: "CD" - Use Definition "at lunch"
- Display: "CV" - Use Definition "at dinner"
Express as:
{offset_value} minute(s) / hour(s) / day(s) {modified_when_value-set}
at breakfast
30 minutes before a meal
1 hour before sleep
2 hours after breakfast
in the morning and in the evening
at night
event.timing
suggests using the during preposition, which differs to the examples above.
Prepositions are interchangeble in the English language (e.g.
during
, in
or at
), and care should be taken to ensure that the appropriate preposition is used in the dosage instruction, for the person administering the medication.
Element: dayOfWeek
Express as:
on {dayOfWeek}
using the full description from the FHIR value-set, i.e. mon
= "Monday
".
Separate multiple statements with a comma and use the word "and
" to separate the final two statements.
on Monday
on Monday, Wednesday and Friday
Element: timeOfDay
Express as:
at {timeOfDay}
Separate multiple statements with a comma and use the word "and
" to separate the final two statements. If a time is expressed with :00
seconds then express just in terms of hours and minutes. Sending systems should always provide times using the 24 hour clock.
Receiving systems may apply local preferences for display, i.e. 15:00
or 3:00pm
.
at 10:00
at 10:00 and 15:00
Element: route
No additional formatting required.
Element site
No additional formatting required.
Elements: asNeededCodeableConcept
/ asNeeded
Express the asNeededBoolean
statement as:
as required
Express the asNeededCodeableConcept
as:
as required for {coded_value_description}
- as required for Migraine
Elements: boundsDuration
/ boundsRange
Express the units in plural when required.
Express boundsDuration
as:
for {value} {units}.
- for 7 days
Express boundsRange
as:
for {low} to {high} {high_units}
- for 2 to 4 hours
Where only boundsRange.low
is defined, express as:
for at least {low} {low_units}
- for at least 2 hours
Where only boundsRange.high
is defined, express as:
for up to {high} {high_units}
- for up to 2 hours
Elements: count
/ countMax
take X times
but a phrasing of take x doses
or use X times
may be preferrable for some use cases.
If count
is 1 (one) then express as:
take once
If count
is 2 (two) then express as:
take twice
Otherwise express count
as:
take {count} times
Where a countMax
is defined, insert with:
to {countMax}
take once
take twice
take 3 times
take 3 to 5 times
Element: event
Express event
statements as:
on {event_value}
Separate multiple statements with a comma and use the word " and " to separate the final two statements.
Local preferences can be used to display the date in dd/mm/yyyy
or dd-mmm-yyyy
format.
on 25/01/2019
on 25-Jan-2019
on 25/01/2019, 25/02/2019 and 25/03/2019
Elements: maxDosePerPeriod
/ maxDosePerAdministration
/ maxDosePerLifetime
Express a maxDosePerPeriod
statement as:
up to a maximum of {numerator_value} {numerator_unit} in {denominator_value} {denominator_unit} Express the time-based units in plural when required.
- up to a maximum of 1000 milligram in 24 hours
Express a maxDosePerAdministration
statement as:
up to a maximum of {value} {unit} per dose
- up to a maximum of 2 milligram per dose
Express a maxDosePerLifetime
statement as:
up to a maximum of {value} {unit} for the lifetime of patient
- up to a maximum of 60 milligram for the lifetime of patient
Element: additionalInstruction
Separate multiple statements with a comma and use the word "and
" to separate the final two statements.
Do not stop taking this medicine except on your doctor's advice
Dissolve or mix with water before taking
and
Contains aspirin
Element: patientInstruction
No additional formatting required.
Multi-Sequence Instructions
When a complete dosing instruction is described by multiple Dosage
elements, the translated dose strings can be concatinated.
Sequential Instructions
Separate sequential instructions (where each sequence
has an incremental value) can be concatinated separated by , then
.
- Anydrug - 50 milligram - once a day - oral - for 1 week
, then
100 milligram - once a day - oral - for 3 weeks
Concurrent Instructions
Separate parallel instructions (where sequence
has the same value) can be concatinated separated by , and
.
- Anydrug - 50 milligram - once a day - in the morning - oral
, and
100 milligram - once a day - in the evening
Open Source & Test Tool
An open source TypeScript function based on this guidance is available from the NHS Digital Github.
A user-facing end-point based on this guidance has been incorporated into the NHS Digital EPSAT testing tool.