Occupational Disease Determination

1. Occupational Disease Determination An Occupational Physician’s Perspective

2. 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

3. 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.

4. 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

5. “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

6. “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

7. Statute of Limitations • Injury - 1 year from diagnosis • Disease - 2 years from diagnosis

8. Categories of Occupational Disease • Cumulative trauma • Other musculoskeletal disorders • Dermatitis • Respiratory disease • Neurological disease • Other systemic disorders

9. Cumulative trauma • Epidemiolologic controversy • Science v. administrative acceptance • Non work factors • Crossover with injuries • Discrete syndromes v. regional pain

10. Epidemiologic controversy • Common in general population • lack of clear dose-response relationship • force, frequency, postures, vibration • Anthropometric variability • multifactorial causation

11. Science v. administrative acceptance

12. Non work factors • Sporting or hobby activities • Prior injury • Systemic disease • Psychosocial stressors

13. Crossover with injuries • Acute strain v. repetetive trauma • Objective findings the same • Coding and Diagnosis • e.g. Wrist strain vs tendonitis

14. Points of View • Injured worker • Employer • Attending Provider • Specialist • Claims manager

15. Causal Inference • Qualitative plausibility • Quantitative plausibility • Temporal relationship • Elimination of alternative explanations

16. 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

17. 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

18. Quantitative Plausibility • Was the exposure level sufficient to cause the disease? • Comparison of the individual’s exposure to published toxicology and epidemiology literature.

19. 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

20. Occupational Diseases • Acute vs. chronic exposure • Transient vs. cumulative exposure • Exposure often remote from disease • cumulative exposures - Cadmium, lead, asbestos • latency periods - Cancer, asbestosis

21. Reconstruction of Exposure • Duration • Nature of agent • Controls • Intensity • Personal protective equipment • Engineering controls

22. 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

23. 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

24. Epidemiology Interpretation • Strength of Association • Consistency between studies and groups • Specificity - exposures and disease • Dose -Response relationship • Coherence and Plausibility • Temporality

25. Prospective Cohort Retrospective Cohort Case Control Cross Sectional Ecological Study Proportionate Mortality Consecutive Case Series Case Reports Single Case Report Study Design Pyramid Relative Value