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https://snomed.atlassian.net/browse/IHTSDO-796

JIRA IHTSDO-796 (artf6364) Occupational disorder modeling Documentation Review

 

Amendment History

Review Timetable

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Table of Contents
1 Glossary
1.1 Domain Terms
2 Introduction
2.1 Purpose
2.2 Audience
2.3 Summary Recommendation
3 Statement of the problem or need
3.1 Summary of problem or need, as reported
3.2 Summary of requested solution
3.3 Statement of problem as understood
3.3.1 Further exploration of the problem
3.4 Analysis of reported problem, including background
3.4.1 Defining 'Occupational disorder'
3.4.2 Background in Epidemiology
3.4.3 Current definition of occupational disorders in SNOMED CT
3.4.4 The SNOMED CT user business case – Occupational health interventions, occupational disease reporting and surveillance
3.4.5 Extent of problem in SNOMED CT – quantification
3.4.6 Summary of classification issues
3.4.7 Causality/causation in disorders and findings in SNOMED CT
4 Risks / Benefits
4.1 Risks of not addressing the problem
4.2 Risks of addressing the problem
5 Requirements: criteria for success and completion
5.1 Criteria for success/completion
5.2 Strategic and/or specific operational use cases
6 Solution Development
6.1 Initial Design
6.1.1 Solution 1: Full definition of occupational disorders using Due to (attribute)
6.1.2 Solution 2: Don't attempt wholesale full definition
6.2 Design Risks
7 Recommendation
7.1 Detailed design final specification
7.2 Content for review as part of 7.1
8 Quality program criteria
8.1 Quality metrics
8.1.1 Quality metric 1
8.1.2 Quality metric 2
8.2 Use case scenarios
9 Project Resource Estimates
9.1 Scope of elaboration phase
9.2 Projection of overall project size and resource requirements
9.2.1 Expected project resource requirement
9.2.2 Expected project impact and benefit
9.3 Scope of construction phase
9.4 Projection of remaining overall project resource requirements
9.4.1 Expected project resource requirement category
9.4.2 Expected project impact and benefit
9.4.3 Indicative resource estimates for construction, transition and maintenance:
10 References

Glossary

Domain Terms

Introduction

Purpose

The purpose of this project is to consider improving the modeling of the concept 115966001 Occupational disorder (disorder) so as to fully define it and hence to appropriately subsume all thus defined occupational disorder content.

SNOMED CT projects transition from Inception Phase  Elaboration Phase  Construction Phase  Transition Phase. This document combines the documentation of the Inception and Elaboration Phases.
The Inception Phase focuses on understanding the problem and its scope, identifying stakeholders and their requirements, and identifying risks.
The purpose of the Elaboration Phase is to develop, document and test one (or more) possible technical solutions, and to reach a recommendation and provide a detailed specification of a preferred solution to be taken forward to the construction phase.

Audience

The audience for this document includes all standards terminology leaders, implementers and users but is especially targeted at those stakeholders from the epidemiology and occupational health domains and others needing to record and report on disorders with an occupational cause so that public health policy and legislation can benefit (and ultimately the general population). The technical nature of the issue and of the possible solutions makes securing public health insight difficult and of questionable value at the inception phase. As enhancement of definition is beneficial or at least neutral then, if this can be done in a way that does not adversely affect other content, there is no need for wider consultation at this point.

Summary Recommendation

The recommended solution is to not attempt wholesale full definition of disorders for their work-relatedness but instead to use a situation concept to record occupational history: 705133000 | History of exposure to occupational risk factor (situation) such that this coding complements the primary diagnosis record. The solution is set out in detail in Sections 6 and 7 but involves one new Event concept and some modeling of content not previously modeled (but in line with current policy not an extension of it).

Statement of the problem or need

Summary of problem or need, as reported

Artifact artf6364 in the IHTSDO Tracker list initiated by Kent Spackman in 2010 describes the problem thus:
Occupational disorder does not have a clear model, and might be something that should be post-coordinated.
E.g. "occupational asthma" is not currently under "asthma".
And occupational disorder is primitive. It needs to become fully defined.
The item does not have any 'Associations' or 'Dependencies' identified in the Tracker in respect of other projects.

Summary of requested solution

As above, the proposal is that a model is developed to allow for occupational disorders to be fully defined. No detail is available on possible models that meet this requirement.

Statement of problem as understood

The statement in the Tracker artifact "'occupational asthma' is not currently under 'asthma'" is no longer true; this anomaly has been corrected with the concept now a subtype of 424199006 | Substance induced asthma (disorder). However, there has been no advance in modeling the concepts through other defining attributes.
The problem can be summarised as a concern that a) not all disorders defined as subtypes of 115966001 | Occupational disorder (disorder) are sufficiently classified by etiology and pathology and that b) not all occupational disorders in SNOMED CT can be found by the list of stated subtypes of 115966001 | Occupational disorder (disorder).

Further exploration of the problem

Whilst all disorder concepts containing the word 'occupation(al)' can be reliably classified, some disorders with an occupational component may not be worded as 'occupational'. Further, some concepts have 'occupation(al)' references in synonymous descriptions but not in their FSN and are not found under Occupational disorder (disorder).
e.g. 15488007 | Melanodermatitis toxica lichenoides (disorder) has a synonymous description:
'Occupational melanosis' but is not defined in SNOMED CT as an occupational disorder.
There is no explicit reference in the Tracker item on why this exercise is worthwhile except as an appropriate exercise in precise classification; nevertheless it is possible to elaborate a strong use case for this piece of work to allow secondary Public Health data collection and analysis. The value to the patient record and treatment course is less obvious but is explored in section 3.4.4 below.
The problem of reliable classification can be remedied by a systematic review of content for occupational causation and by work to appropriately define content by supertype. However, because this 'single point in time' approach lacks continuity there is a risk of inadequate classification of new content and slow drift away from reliability. Therefore, to ensure a sustainable model, a means of modeling content through other defining attributes is suggested in the tracker item.

Analysis of reported problem, including background

Defining 'Occupational disorder'

Bernardino Ramazzini (1633 – 1714), often called the 'father of Occupational Medicine', proposed that physicians should extend the list of questions that Hippocrates recommended they ask their patients by adding: "What is your occupation?"
The World Health Organization describes an occupational disease as "any disease contracted primarily as a result of an exposure to risk factors arising from work activity". "Work-related diseases have multiple causes, where factors in the work environment may play a role, together with other risk factors, in the development of such diseases."
An "occupational risk factor" is defined by Karjalainen (see below) as "a chemical, physical, biological or other agent that may cause harm to an exposed person in the workplace and is potentially modifiable".
"People at work face a variety of hazards owing to chemicals, biological agents, physical factors, adverse ergonomic conditions, allergens, a complex network of safety risks, and many and varied psychosocial factors. In addition to injuries, more than 100 occupational diseases have been classified according to the tenth revision of the International Classification of Diseases and Related Health Problems (ICD-10). Broadly, these include respiratory, musculoskeletal, cardiovascular, reproductive, neurotoxic, skin and psychological disorders, hearing loss and cancers".
Karjalainen, A: Comparative Quantification of Health Risks Ch21 p1653 World Health Organization http://www.who.int/healthinfo/global_burden_disease/cra/en/
However, as Karjalainen states: "The absence of unified diagnostic criteria, coding systems and classifications reduces the compatibility and comparability of national statistics on occupational diseases."

Background in Epidemiology

In 1900, the three top causes of death in the U.S. were pneumonia, tuberculosis, and gastroenteritis. In 1990, the top causes of death in the U.S. were heart disease, cancer, stroke, accidents and chronic obstructive lung disease and remain so today. This shift from acute infectious cause of death to chronic disease has led to a more contemporary model of disease causation being applied to epidemiology including multiple risk factors, long latency periods, and differences in individual responses to disease causing agents.

Current definition of occupational disorders in SNOMED CT

115966001 | Occupational disorder (disorder) is defined as an environment related disease and is Primitive:

The SNOMED CT user business case – Occupational health interventions, occupational disease reporting and surveillance

The importance of reporting and surveillance of occupationally related disease is well documented. It is beyond the scope of this document to describe this in any detail. However, it is worth noting that occupational repiratory disease surveillance is particularly well organised and established around the world.
"Classifications of occupational diseases have been developed mainly for two purposes: (1) notification for labor safety and health surveillance and (2) compensation." Karjaleinen
"An occupational disease is not characterised merely by the disease itself, but by a combination of a disease and an exposure, as well as an association between these two." ibid
This is a key point. It means that SNOMED representations of both disease and exposure need to be considered.
In looking at SNOMED issues in this matter we may be straying into classifications territory. ICD-10 relies largely on primary diagnoses in notifications where the notification itself gives the occupational context. However most of the content found in SNOMED describing 'occupational disorder' comes from ICD. What is defined in ICD is not automatically what should be defined in SNOMED and the case needs making. In general, there may be no histopathological features to distinguish an occupational case of a disorder from a non-occupational one. Many specified ICD derived lung diseases under 'Extrinsic allergic alveolitis/Hypersensitivity pneumonitis' appear to be only different words for the same thing with a risk factor exposure element added on. Whether it should be left to ICD or to the notification context it might be argued that this can then be left out of scope of SNOMED CT. The requirements for secondary data collections are distinct and separate from those expected of clinical diagnosis. However, to argue the contrary: it may well be germane to the course of care to identify the causal exposure along with the disorder so that the exposure can be removed (if it is still present), limited or mitigated in some way. This does not prevent a cross-map to a less granular ICD-10 primary diagnosis code for notification purposes. It may also be important from an individual perspective to gain a definitive diagnosis that clearly associates the disorder with an occupational exposure for reasons of legal action, compensation or retirement, pensions, care costs etc. even where the course of treatment is the same whether occupational or non-occupational in origin. Where the individual is still working in the same environment then occupational health interventions could be identified and coded to remedy or mitigate the risk and even in cases where the individual has moved on or retired there still remain sound reasons for recording the origin of the condition to their or others' advantage. It may simply be that, despite it not affecting the clinical treatment course, "ars longa…" makes going the extra distance to record the causative or at least associated environmental factor worthwhile and the diligent clinical historian may be thanked by posterity.

Extent of problem in SNOMED CT – quantification

The Tracker item presents the possibility of diseases with an occupational component not being classified as such and conversely the risk of some subtypes of 115966001 Occupational disorder (disorder) not being additionally classified by their pathology/aetiology in some way.

Content classified under 115966001 Occupational disorder (disorder)

The (July 2015 Edition) list of 100 subtypes of 115966001 Occupational disorder (disorder)

: