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2DR.S.H.HASHEMI

(Occupational medicine practice guidelines)

WORK-RELATEDNESS

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Occupational physicians often are asked for an opinion as to whether or not a problem is work related.

Determining whether a symptom, illness, or injury is due to work, is important to: Patient Other workers exposed to similar conditions Employer

A determination that a symptom, injury, or illness was caused by work can lead to immediate preventive assessments or protective efforts .

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Medical causation and legal causation are different concepts, and it is important that the occupational medicine physician understand the differences.

Medical causation is physical or biological in nature [ i.e. a physician may conclude that a substance in a

workplace is likely to be the cause of a pulmonary adenocarcinoma]

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Legal causation, generally has two components: Cause in fact Proximate cause

Cause in fact exists when the occurrence of an event brings about a result. [i.e. prior close contact with a patient with meningitis may

be deemed the cause in fact of a patient's meningococcemia]

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Proximate cause relates to concepts such as the predictability or remoteness of an event. [i.e. suppose a physician prescribes a patient a medication,

which is consumed later at home by the patient's child, who dies as a result. A court may find that prescribing the medication was the cause in fact, but not the proximate cause, of the child's death. ]

Legal cause exists only when both cause in fact and proximate cause have been proven.

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DEFINITIONS OF CAUSATION AND RELATED TERMS

While assessing causation can be relatively straightforward, as it is commonly in direct trauma, determining whether a complaint is related to work often requires careful analysis and weighing all associated or apparently causal factors operative over time.

The commonly seen statement "in the absence of other obvious causes, the problem is work related" should not be used. Such language is not reflective of the scientific basis, it

mostly shows financial and legal responsibility.

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DEFINITIONS OF CAUSATION AND RELATED TERMS … In general, if there is no clear mechanism of injury

and the physical examination is negative, it is preferable to provide analysis, reassurance, and recommendations regarding prevention rather than give a vague tissue diagnosis suggesting an "injury."

It is often helpful to involve the patient in the analytic process and in his or her causation analysis.

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Single, Multiple, or Competing causation The physician may determine and state whether a

workplace factor is the only cause, one among several contributing causes, or one of several possible causes, each of which could independently produce the disorder.

Single causation : A direct cause can generally

be attributed if both the immediate trauma and the effect are clearly observable.

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Single, Multiple, or Competing causation . . .

Multiple causation : Health problems may develop as the result of a combination

of factors, only some of which may be work related. [i.e. hearing loss may occur as a result of aging as well as

occupational noise exposure ]

Occupational and nonoccupational exposures may have a combined effect. [i.e. Carpal tunnel syndrome : physical exposures, personal

risk factors such as DM or RA ]

Personal factors also can be part of the "web of causation." [i.e. tall individuals have a greater probability of

developing back pain in certain settings ]

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Single, Multiple, or Competing causation . . .Competing causation: Competing causation differs from combined causation

in that either a workplace factor or a nonoccupational factor, but not both, can be responsible independently for the adverse health effect.

[i.e. because pregnancy, diabetes, myxedema, tobacco, and stereotypical high-force motions have been independently associated with carpal tunnel syndrome, a patient with diabetes who does very little stereotypical work will most likely develop carpal tunnel syndrome due to the diabetes, not the nature of his or her work.]

a

MEDIANNERVE

CARPALLIGAMENT

TENDONSBONES

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Recurrence, Exacerbation, and Aggravation

The distinction between a recurrence, exacerbation, and an aggravation of a condition also is important medically and legally.

A recurrence of an ongoing condition arises from the same etiology as the preexisting condition, which may be a prior work injury.

Recurrence generally involves the reappearance of signs or symptoms attributable to a prior injury with minimal or no provocation (i.e., in the absence of a clearly definable injury or precipitating factor). [ i.e. radicular pain that develops after minimal effort in a

patient with a previously documented work-related disk herniation. ]

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Recurrence, Exacerbation, and Aggravation . . . .

Exacerbation : Transient worsening of a prior condition by an injury or

illness With the expectation that the situation will eventually

return to baseline

Aggravation : Permanently worsens an existing condition New event

Aggravations can include those situations in which a process was without symptoms until the precipitating event occurred.

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Recurrence, Exacerbation, and Aggravation . . . .

If an underlying condition is aggravated or exacerbated at work, it is important to document the impairment, pain, and activity limitation .

Restoring prior activity levels is a principal goal of treatment.

When and if that goal is reached, the exacerbation will be said to have ceased.

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Recurrence, Exacerbation, and Aggravation . . . Because an aggravation of a prior condition has led

to a permanent alteration in the patient's underlying condition, the work injury cannot be described as cured; regardless of whether a full return to work occurs, there is potential for future recurrence of symptoms.

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Methods for Determining Work-relatedness NIOSH six-step process:

Evidence of Disease: What is the disease? What certainty is there that the diagnosis is correct?what evidence supports or fails to support that diagnosis?

Epidemiology: What is the epidemiological evidence for that condition? Is there support for a relationship with work?

Evidence of Exposure: What evidence, particularly objective, is there that the level of exposure is of the frequency, intensity, and duration of exposure to rise to the level that would support a work-relatedness determination?

Consideration of Other Relevant Factors: What other factors are present in this case? For example, is the worker with carpal tunnel syndrome (CTS) pregnant or obese?

Validity of Testimony: Is there information that suggests that the information above is inaccurate, for example, from a collateral source?

Conclusions: This step is a synthesis of the above five steps.

Did the employee experiencean injury or illness?

Is the injury or illnesswork related?

Is the injury or illnessa new case?

Update the previouslyrecorded injury or illness if necessary.

Does the injury or illness meet thegeneral recording criteria or the

application to specific cases?

Do not need to recordthe injury or illness.

Recordthe injury or illness.

NO

NO

NO

NO

YES

YES

YES

YES

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Criteria for the evaluation of epidemiologic evidence

Temporal association between the exposure or work factor and the health concern (i.e., the exposure must precede the disease).

Strength of the association (e.g., how large is the relative risk or odds ratio that compare the exposed with the unexposed workers?)

Dose-response

Consistency of the association among epidemiological studies

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Criteria for the evaluation of epidemiologic evidence . . .

Predictive performance of the association in predicting future health problems .

Experimental evidence from animal models . Analogy (e.g., evidence of effects from a chemical

with analogous structure) . Specificity of the association in showing that the

exposure causes one problem rather than a large group of unrelated problems .

Plausibility of the purported exposure-disease relationship .

Reversibility (e.g., that the tissue abnormalities resolve with cessation of exposure).

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HISTORY (Initial and interval)

A careful medical history, essential in establishing the work-relatedness of a complaint.

Elicit a description of activity limitations and pain levels both before and after a work injury or aggravation.

It also is beneficial to obtain a psychiatric history in situations where the patient presents with psychiatric or stress-related complaints.

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HISTORY (Initial and interval) . . .

One link between exposures and health effects is their temporal relationship.

The clinician may determine the time course of events, carefully documenting the time of potential exposures or trauma and of symptom onset.

While the onset of subacute or chronic conditions may be gradual, the patient can generally provide time estimates.

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HISTORY (Initial and interval) . . .

Also of relevance is whether or not symptoms decrease overnight or during weekends, holidays, or other times the patient is not exposed. Where one would ordinarily expect to see some degree of

symptom resolution once exposure to the injurious factor has ceased.

Determining temporal causality might be difficult with certain psychiatric problems such as PTSD because the onset of symptoms may be delayed temporally for quite some time relative to the trauma causing them.

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HISTORY (Initial and interval) . . .

Workplace exposures also need to be quantified as much as possible in the history.

The patient can describe his or her typical workday and any unusual events preceding the onset of complaints.

Unusual events might include: Changes in workload Physical or chemical processes Absence or breakdown of :

Engineering controls Personal protective equipment

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HISTORY (Initial and interval). . .

Psychiatric or stress-related complaints require assessing worksite exposure to acute stresses, such as:Workplace violenceMismatched workloadSkills and abilitiesRole ambiguityLack of control

Interpersonal relationships with supervisors and coworkers may be documented as well.

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HISTORY (Initial and interval). . .

The inquiry includes relevant : Personal habits

substance use(tobacco, alcohol, and others with adverse health effects)

Coexisting disease states Family history

The patient also can be asked about similar occupational or nonoccupational problems and their resolution in the past.

Carefully address nonwork activities,(recreational activities or hobbies) that could precipitate similar symptoms.

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HISTORY (Initial and interval). . . .

In short, when taking the worker's history, the goal should always be to obtain answers to the following questions: Was there a temporal relationship between the exposure

and the effect?

Was the amount (duration, dose, strength) of the exposure sufficient to cause an effect in most workers?

Could other causes (personal, comorbid, or nonoccupational) possibly account for the symptom, illness, or injury in question?

Could the exposure have been mitigated by engineering controls, personal protective equipment, immunization, or other means?

Is the health effect causing functional impairment? Is it causing work exclusion?

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WORKPLACE environment assessment Information about:

Workplace ergonomic exposures Typical job duties Maximal effort needed to perform the job

Specific descriptions and comparisons being more useful than general descriptions such as "heavy”.

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WORKPLACE environment assessment . . . The clinician might inquire about:

Total force used Local concentration of force (a forcefully applied grasp

on a sharp tool handle edge) Frequency of specific motions or tasks Awkward postures Job satisfaction Other factors (cold and vibration)

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WORKPLACE environment assessment . . . Summaries of health effects from material safety

data sheets (MSDSs) may prove useful in guiding the clinical inquiry and subsequent literature searches.

Use the appropriate measure for chemical, physical, and biologic agents (time-weighted averages versus peak exposures).

If possible, measurements should be concurrent with the time course of the problem, rather than using current measurements to impute previous exposure.

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WORKPLACE environment assessment . . . A worksite visit by the occupational physician may be useful.

Measurements by an ergonomist or an industrial hygienist, depending on the issue, may be needed to quantify exposure.

Area or personal monitoring data are more useful to prove and quantify exposure .

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SUMMARY

Determining work-relatedness is important to: Assure delivery of appropriate workers' compensation

benefits Prevent exacerbations and recurrences of the condition

Preventive efforts also are needed to be sure that other workers do not experience similar problems.

If work causes or contributes to illness and the exposure cannot be controlled, reassigning the worker may be necessary.

THE END

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