Status: this page is in development.
Overview
NOTE: In this page, we use the term ‘decision logic module’ (DLM) for convenience, and it should not be taken to be a permanent name. Other names such as ‘computerised guideline module’ (CGM), ‘clinical practice guideline’ (CPG) etc are also common.
The problem
The aim of this page is to describe the form of a ‘decision logic module’ (DLM) that can be used in at least the following scenarios:
...
This achieves the same effect as the openEHR Element type, just in a simpler type system. This approach enables typical null-value rules to be defined, such that an expression such as ejection_fraction > 20% will not cause an exception even if the ejection_fraction raw value is null. Of course it is usually better to test for defined (ejection_fraction) first, if ejection_fraction was defined as Quantity?.
QUESTION: We might have to consider whether using the ‘?' declaration obscures the difference between a 'non-available’ variable (i.e. no value available from the outside world) and one that is simply null in the standard programming language sense. If we assume that the latter can happen within datasets and guidelines, we might want to allow both Type? and e.g. the use of the explicit type Data_item<T> to distinguish the two cases.
Effective time
Sometimes the clinically significant time of a data item needs to be accessed in rules. This can be done by the reference x.effective_time, e.g. ejection_fraction.effective_time returns when the ejection fraction measurement being used was taken. For a variable like is_diabetic, it means when the diagnosis was made.
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| Code Block |
|---|
dlm RCHOPS21
language
original_language = <[ISO_639-1::en]>
description
lifecycle_state = <"unmanaged">
original_author = <
["name"] = <"Dr Spock">
["organisation"] = <"Acme healthcare">
["date"] = <"2020-03-22">
>
details = <
["en"] = <
language = <[ISO_639-1::en]>
purpose = <"NHS CHOPS-21 chemotherapy guideline ....">
>
>
use
BSA: Body_surface_area
reference
paracetamol_dose: Quantity = 1g
chlorphenamine_dose: Quantity = 10mg
prednisolone_dose_per_m2: Quantity = 40mg
rituximab_dose_per_m2: Quantity = 375mg
doxorubicin_dose_per_m2: Quantity = 50mg
vincristine_dose_per_m2: Quantity = 1.4mg
cyclophosphamide_dose_per_m2: Quantity = 750mg
cycle_period: Duration = 3w
cycle_repeats: Integer = 6
input -- <time_window = "current_episode">
staging: Terminology_term «ann_arbor_staging»
currency = 30 days
has_metastases: Boolean
currency = 30 days
input
neutrophils: Quantity
currency = 3d
ranges = {
[normal]: |>1 x 10^9/L|,
[low]: |0.5 - 1 x 10^9/L|,
[very_low]: |<0.5 x 10^9/L|
}
platelets: Quantity
currency = 12h
ranges = {
[normal]: |>75 x 10^9/L|,
[low]: |50 - 74 x 10^9/L|,
[very_low]: |<50 x 10^9/L|
}
bilirubin: Quantity
currency = 12h
ranges = {
[normal]: |<20 mmol/L|,
[high]: |20 - 51 mmol/L|,
[very_high]: |51 - 85 mmol/L|,
[crit_high]: |>85 mmol/L|
}
gfr: Quantity
currency = 24h
ranges = {
[normal]: |>20 mL/min|,
[low]: |10 - 20 mL/min|,
[very_low]: |<10 mL/min|
}
ldh: Quantity
currency = 24h
ranges = {
[normal]: |>20 mL/min|,
[low]: |10 - 20 mL/min|,
[very_low]: |<10 mL/min|
}
conditions
high_ipi:
Result <- ipi_risk ∈ {|[ipi_high _risk|3], |[ipi_intermediate-_high _risk|2]}
|
| patient fit to undertake regime
|
patient_fit:
Result <- not
(platelets.in_range (very_low) or
neutrophils.in_range (very_low))
rules
prednisolone_dose: Quantity
Result <- prednisolone_dose_per_m2 * BSA.bsa_m2
rituximab_dose: Quantity
Result <- rituximab_dose_per_m2 * BSA.bsa_m2
doxorubicin_dose: Quantity
Result <- doxorubicin_dose_per_m2 * BSA.bsa_m2 *
map bilirubin.range {
[high]: 0.5,
[very_high]: 0.25,
[crit_high]: 0.0
}
prednisolone_dose: Quantity
Result <- prednisolone_dose_per_m2 * BSA.bsa_m2
|
| TODO: hepatic impairment dose modification
|
vincristine_dose: Quantity
Result <- vincristine_dose_per_m2 * BSA.bsa_m2
|
| CHECK: is low platelets and GFR dose modification
| cumulative?
|
cyclophosphamide_dose: Quantity
Result <- cyclophosphamide_dose_per_m2 * BSA.bsa_m2
* map platelets.range {
[normal]: 1,
[low]: 0.75
}
* map gfr.range {
[normal]: 1,
[low]: 0.75,
[very_low]: 0.5
}
|
| International Prognostic Index
| ref: https:|en.wikipedia.org/wiki/International_Prognostic_Index
|
| One point is assigned for each of the following risk factors:
| Age greater than 60 years
| Stage III or IV disease
| Elevated serum LDH
| ECOG/Zubrod performance status of 2, 3, or 4
| More than 1 extranodal site
|
| The sum of the points allotted correlates with the following risk groups:
| Low risk (0-1 points) - 5-year survival of 73%
| Low-intermediate risk (2 points) - 5-year survival of 51%
| High-intermediate risk (3 points) - 5-year survival of 43%
| High risk (4-5 points) - 5-year survival of 26%
|
ipi_raw_score: Integer
if age > 60
Result <- Result + 1
if staging ∈ {|stage III|, |stage IV|}
Result <- Result + 1
if ldh.in_range (normal)
Result <- Result + 1
if ecog > 1
Result <- Result + 1
if extranodal_sites > 1
Result <- Result + 1
ipi_risk: Terminology_code
Result <-
map ipi_raw_score {
|0..1| : |[ipi_low risk: 5y survival - 73%|0_risk],
|2| : |[ipi_intermediate-_low risk: 5y survival - 51%|1_risk],
|3| : |[ipi_intermediate-_high risk: 5y survival - 43%|2_risk],
|4..5| : |[ipi_high _risk:]
5y survival - 26%|3
}
terminology
term_definitions = <
["en"] = <
["paracetamol_dose"] = <
text = <"paracetamol dose">
description = <"paracetamol base dose level per sq. m of BSA">
>
["chlorphenamine_dose"] = <
text = <"chlorphenamine dose">
description = <"chlorphenamine base dose level per sq. m of BSA">
>
...
["staging"] = <
text = <"Cancer staging">
description = <"Cancer staging (Ann Arbor system)">
>
["has_metastases"] = <
text = <"Metastatic status">
description = <"Status of metastasis of cancer">
>
...
["neutrophils"] = <
text = <"neutrophils">
description = <"neutrophils level">
>
["platelets"] = <
text = <"platelets">
description = <"platelets level">
>
...
["ipi_low_risk"] = <
text = <"low risk: 5y survival - 73%">
description = <"..">
>
["ipi_intermediate_low_risk"] = <
text = <"intermediate-low risk: 5y survival - 51%">
description = <"..">
>
["ipi_intermediate_high_risk"] = <
text = <"intermediate-high risk: 5y survival - 43%">
description = <"...">
>
["ipi_high_risk"] = <
text = <"high risk: 5y survival - 26%">
description = <"...">
>
>
> |
Questions
DLM - DLM relationships
...