Occupational Disease
Determination
An
Occupational
Physician’s
Perspective
Dennis Stumpp, MD, MS
• Board certified, residency trained
Occupational medicine
• Current Position
– Staff physician Valley Medical Center
Occupational Health Services - Auburn 30
hours/week
– IME’s and consulting
Legal Definitions
RCW 51.08.100
"Injury."
•
"Injury" means a sudden and tangible happening, of a traumatic nature,
producing an immediate or prompt result, and occurring from without, and
such physical conditions as result therefrom.
RCW 51.08.140
"Occupational disease."
•
"Occupational disease" means such disease or infection as arises naturally
and proximately out of employment under the mandatory or elective adoption
provisions of this title.
Criteria For Allowance
• Physician opinion more probable than not
that work conditions are the cause of or
have temporarily or permanently
aggravated a pre-existing condition
• Supporting objective medical findings
• Arose naturally and proximately out of
employment
“Naturally”
• A natural consequence of distinctive
conditions of employment OR
• A natural consequence of work conditions
rather than conditions in everyday life or all
employment in general OR
• A natural consequence of conditions of
employment rather than conditions
occurring coincidentally in the workplace
“Proximately”
• There existed no intervening independent
and sufficient cause for the disease so
that the disease would not have been
contracted but for the distinctive
condition existing in the … employment
• not required to be the only cause
Statute of Limitations
• Injury - 1 year from diagnosis
• Disease - 2 years from diagnosis
Categories of Occupational
Disease
• Cumulative trauma
• Other musculoskeletal disorders
• Dermatitis
• Respiratory disease
• Neurological disease
• Other systemic disorders
Cumulative trauma
• Epidemiolologic controversy
• Science v. administrative acceptance
• Non work factors
• Crossover with injuries
• Discrete syndromes v. regional pain
Epidemiologic controversy
• Common in general population
• lack of clear dose-response relationship
– force, frequency, postures, vibration
• Anthropometric variability
• multifactorial causation
Science v. administrative
acceptance
Non work factors
• Sporting or hobby activities
• Prior injury
• Systemic disease
• Psychosocial stressors
Crossover with injuries
• Acute strain v. repetetive trauma
• Objective findings the same
• Coding and Diagnosis
• e.g. Wrist strain vs tendonitis
Points of View
• Injured worker
• Employer
• Attending Provider
• Specialist
• Claims manager
Causal Inference
• Qualitative plausibility
• Quantitative plausibility
• Temporal relationship
• Elimination of alternative explanations
Temporal Relationship
• Exposure precedes disease
• Symptoms occur in proper relationship to
exposure
– Acutely during exposure, disappearing after exposure
ceases, better on evenings, weekends and holidays
– Chronologicaly appropriate duration and latency
period
Qualitative Plausibility
• Is the disease/symptoms consistent with the
known toxic effects of the substance?
• In the absence of adequate literature
– Are there others similarly exposed experiencing the
same disease
– Does the offending substance share chemical or
structural characteristics with other substances
known to cause the disease
Quantitative Plausibility
• Was the exposure level sufficient to
cause the disease?
• Comparison of the individual’s exposure
to published toxicology and epidemiology
literature.
Alternative causation
• Is there a more likely or preferable
explanation of causation?
– Natural course of pre-existing disease
– new disease onset of other cause
– concurrent disease process resulting in some
of symptoms
– multifactorial cause
Occupational Diseases
• Acute vs. chronic exposure
• Transient vs. cumulative exposure
• Exposure often remote from disease
– cumulative exposures - Cadmium, lead,
asbestos
– latency periods - Cancer, asbestosis
Reconstruction of Exposure
• Duration
• Nature of agent
• Controls
• Intensity
• Personal protective equipment
• Engineering controls
Sources of Information
• Patient history
• Medical Records - outside PMD’s, present and prior
• Medical surveillance
• MSDS’s
• Industrial hygiene measurements
• Human resources
• Worksite walk through
Epidemiology and Toxicology of
Occupational Disease
• Study Quality
– Variety of Study Types
– Animal v. human data
– Similar type and route of exposure
– Random variation
– Bias
– Statistical v. clinical significance
Epidemiology Interpretation
• Strength of Association
• Consistency between studies and groups
• Specificity - exposures and disease
• Dose -Response relationship
• Coherence and Plausibility
• Temporality
Study Design Pyramid
Prospecti
ve
Cohort
Retrospective
Cohort
Case Control
Cross Sectional
Ecological Study
Proportionate Mortality
Consecutive Case
Series
Case Reports
Single Case Report
Relative Value