Occupational Disease Occupational Disease DeterminationDetermination

An Occupational Physician’s Perspective

Dennis Stumpp, MD, MSDennis Stumpp, MD, MS

• Board certified, residency trained Board certified, residency trained Occupational medicineOccupational medicine

• Current PositionCurrent Position– Staff physician Valley Medical Center Staff physician Valley Medical Center

Occupational Health Services - Auburn Occupational Health Services - Auburn 30 hours/week 30 hours/week

– IME’s and consultingIME’s and consulting

Legal DefinitionsLegal 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 AllowanceCriteria For Allowance

• Physician opinion more probable than Physician opinion more probable than not that work conditions are the cause not that work conditions are the cause of or have temporarily or permanently of or have temporarily or permanently aggravated a pre-existing conditionaggravated a pre-existing condition

• Supporting objective medical findingsSupporting objective medical findings

• Arose naturally and proximately out of Arose naturally and proximately out of employmentemployment

““Naturally”Naturally”

• A natural consequence of distinctive A natural consequence of distinctive conditions of employment conditions of employment OROR

• A natural consequence of work conditions A natural consequence of work conditions rather than conditions in everyday life or all rather than conditions in everyday life or all employment in general employment in general OROR

• A natural consequence of conditions of A natural consequence of conditions of employment rather than conditions employment rather than conditions occurring coincidentally in the workplaceoccurring coincidentally in the workplace

““Proximately”Proximately”

• There existed no intervening There existed no intervening independent and sufficient cause for independent and sufficient cause for the disease so that the disease the disease so that the disease would not have been contracted would not have been contracted but but forfor the distinctive condition existing the distinctive condition existing in the … employmentin the … employment

• not required to be the only causenot required to be the only cause

Statute of LimitationsStatute of Limitations

• Injury - 1 year from diagnosisInjury - 1 year from diagnosis

• Disease - 2 years from Disease - 2 years from diagnosisdiagnosis

Categories of Categories of Occupational DiseaseOccupational Disease

• Cumulative traumaCumulative trauma

• Other musculoskeletal disordersOther musculoskeletal disorders

• DermatitisDermatitis

• Respiratory diseaseRespiratory disease

• Neurological diseaseNeurological disease

• Other systemic disordersOther systemic disorders

Cumulative traumaCumulative trauma

• Epidemiolologic controversyEpidemiolologic controversy

• Science v. administrative acceptanceScience v. administrative acceptance

• Non work factors Non work factors

• Crossover with injuriesCrossover with injuries

• Discrete syndromes v. regional painDiscrete syndromes v. regional pain

Epidemiologic controversyEpidemiologic controversy

• Common in general populationCommon in general population

• lack of clear dose-response lack of clear dose-response relationshiprelationship– force, frequency, postures, vibrationforce, frequency, postures, vibration

• Anthropometric variabilityAnthropometric variability

• multifactorial causationmultifactorial causation

Science v. administrative Science v. administrative acceptanceacceptance

Non work factors Non work factors

• Sporting or hobby activitiesSporting or hobby activities

• Prior injuryPrior injury

• Systemic diseaseSystemic disease

• Psychosocial stressorsPsychosocial stressors

Crossover with injuriesCrossover with injuries

• Acute strain v. repetetive traumaAcute strain v. repetetive trauma

• Objective findings the sameObjective findings the same

• Coding and Diagnosis Coding and Diagnosis

• e.g. Wrist strain vs tendonitise.g. Wrist strain vs tendonitis

Points of ViewPoints of View

• Injured workerInjured worker

• Employer Employer

• Attending ProviderAttending Provider

• SpecialistSpecialist

• Claims managerClaims manager

Causal InferenceCausal Inference

• Qualitative plausibilityQualitative plausibility

• Quantitative plausibilityQuantitative plausibility

• Temporal relationshipTemporal relationship

• Elimination of alternative Elimination of alternative explanationsexplanations

Temporal RelationshipTemporal Relationship

• Exposure precedes diseaseExposure precedes disease

• Symptoms occur in proper relationship to Symptoms occur in proper relationship to exposureexposure– Acutely during exposure, disappearing after Acutely during exposure, disappearing after

exposure ceases, better on evenings, exposure ceases, better on evenings, weekends and holidaysweekends and holidays

– Chronologicaly appropriate duration and Chronologicaly appropriate duration and latency periodlatency period

Qualitative PlausibilityQualitative Plausibility

• Is the disease/symptoms consistent with Is the disease/symptoms consistent with the known toxic effects of the substance?the known toxic effects of the substance?

• In the absence of adequate literatureIn the absence of adequate literature– Are there others similarly exposed Are there others similarly exposed

experiencing the same diseaseexperiencing the same disease

– Does the offending substance share chemical Does the offending substance share chemical or structural characteristics with other or structural characteristics with other substances known to cause the diseasesubstances known to cause the disease

Quantitative PlausibilityQuantitative Plausibility

• Was the exposure level sufficient to Was the exposure level sufficient to cause the disease?cause the disease?

• Comparison of the individual’s Comparison of the individual’s exposure to published toxicology exposure to published toxicology and epidemiology literature.and epidemiology literature.

Alternative causationAlternative causation

• Is there a more likely or preferable Is there a more likely or preferable explanation of causation?explanation of causation?– Natural course of pre-existing diseaseNatural course of pre-existing disease

– new disease onset of other causenew disease onset of other cause

– concurrent disease process resulting in concurrent disease process resulting in some of symptomssome of symptoms

– multifactorial causemultifactorial cause

Occupational DiseasesOccupational Diseases

• Acute vs. chronic exposureAcute vs. chronic exposure

• Transient vs. cumulative exposureTransient vs. cumulative exposure

• Exposure often remote from diseaseExposure often remote from disease– cumulative exposures - Cadmium, lead, cumulative exposures - Cadmium, lead,

asbestosasbestos

– latency periods - Cancer, asbestosislatency periods - Cancer, asbestosis

Reconstruction of Reconstruction of ExposureExposure

• DurationDuration

• Nature of agentNature of agent

• ControlsControls

• IntensityIntensity

• Personal protective equipmentPersonal protective equipment

• Engineering controlsEngineering controls

Sources of InformationSources of Information

• Patient historyPatient history

• Medical Records - outside PMD’s, present and priorMedical Records - outside PMD’s, present and prior

• Medical surveillanceMedical surveillance

• MSDS’sMSDS’s

• Industrial hygiene measurementsIndustrial hygiene measurements

• Human resourcesHuman resources

• Worksite walk throughWorksite walk through

Epidemiology and Toxicology Epidemiology and Toxicology of Occupational Diseaseof Occupational Disease

• Study QualityStudy Quality– Variety of Study TypesVariety of Study Types

– Animal v. human dataAnimal v. human data

– Similar type and route of exposureSimilar type and route of exposure

– Random variationRandom variation

– BiasBias

– Statistical v. clinical significanceStatistical v. clinical significance

Epidemiology Epidemiology InterpretationInterpretation

• Strength of AssociationStrength of Association

• Consistency between studies and groupsConsistency between studies and groups

• Specificity - exposures and diseaseSpecificity - exposures and disease

• Dose -Response relationshipDose -Response relationship

• Coherence and PlausibilityCoherence and Plausibility

• TemporalityTemporality

ProspectiveCohort

RetrospectiveCohort

Case Control

Cross Sectional

Ecological Study

Proportionate Mortality

Consecutive Case SeriesCase Reports

Single Case Report

Study Design Pyramid

Relative Value