Causation Assessment - The Basics
Many clinicians focus on aspects of clinical care for their patients, i.e. what is appropriate evaluation and treatment, and may not be formally trained in causation analysis or epidemiology, nor may they be familiar with the most current science. Therefore, it useful to review the current science and the process of determining whether a condition is work-related. In the AMA Guides series of publications, the Guides to the Evaluation of Disease and Injury Causation provides guidance on the process of causation and apportionment analysis. This publication provides guidance on understanding work-relatedness, methodology, causality examination, and provides chapters dealing with specific regions.
Causality requires determination that each of the following has occurred to a reasonable degree of medical certainty:
Causation analysis must be based on facts and scientific evidence. The premise of causation is that a given cause (A) and effect (B) are etiologically associated with a reasonable degree of medical probability or certainty, ie, more than 50% probability. The premise that, within a reasonable degree of medical probability, A and B are causally related assumes that all 3 of the following criteria are true (medically probable):
1. The cause (A) is medically probable: more likely than not the patient experienced a trauma or exposure (A).
2. The effect (B) is medically probable: more likely than not the patient has the injury or illness.
3. A and B probably are causally related: more likely than not the trauma caused the injury or the exposure caused the illness.
This is the premise physicians are asked to analyze and to support or refute when assessing causality: that a probable cause (A) and effect (B) likely are etiologically related. If any 1 of the 3 criteria is possible, but not probable, causation has not been established. Further, 2 or more possible causes or effects do not equal a probable one (they are not additive).
It appears that some physicians opine that certain work events caused or aggravated a condition on the basis of a temporal relationship, without a scientific basis to support these conclusions, and these opinions are accepted by fact finders without further analysis. This results in faulty decisions on these cases and a failure of the patient to understand the true nature of the condition.
In 1965, Bradford Hill identified 9 criteria to consider when assessing whether the purported relationship between a cause and an effect was one of causation or simply association. This causation analysis checklist is sometimes referred to as the Bradford Hill criteria.
Medical apportionment is an estimate of the extent to which two or more probable factors caused an injury or disease. When apportioning responsibility for an injury or disease, one must first consider all potential causes and then determined whether each is probable or possible. A compensable injury or disease may exacerbate or aggravate a pre-existing condition, but may also be temporarily or partly worsened by subsequent trauma or exposure. Many illnesses are multifactorial in etiology. Physicians must be aware of the current medical literature to determine the causes for a condition, including occupational and nonoccupational causes and the significance of these causes.
Causality requires determination that each of the following has occurred to a reasonable degree of medical certainty:
- A causal event took place.
- The patient experiencing the event has the condition (eg, impairment).
- The event could cause the condition.
- The event caused or medically contributed to the condition within medical probability.
Causation analysis must be based on facts and scientific evidence. The premise of causation is that a given cause (A) and effect (B) are etiologically associated with a reasonable degree of medical probability or certainty, ie, more than 50% probability. The premise that, within a reasonable degree of medical probability, A and B are causally related assumes that all 3 of the following criteria are true (medically probable):
1. The cause (A) is medically probable: more likely than not the patient experienced a trauma or exposure (A).
2. The effect (B) is medically probable: more likely than not the patient has the injury or illness.
3. A and B probably are causally related: more likely than not the trauma caused the injury or the exposure caused the illness.
This is the premise physicians are asked to analyze and to support or refute when assessing causality: that a probable cause (A) and effect (B) likely are etiologically related. If any 1 of the 3 criteria is possible, but not probable, causation has not been established. Further, 2 or more possible causes or effects do not equal a probable one (they are not additive).
It appears that some physicians opine that certain work events caused or aggravated a condition on the basis of a temporal relationship, without a scientific basis to support these conclusions, and these opinions are accepted by fact finders without further analysis. This results in faulty decisions on these cases and a failure of the patient to understand the true nature of the condition.
In 1965, Bradford Hill identified 9 criteria to consider when assessing whether the purported relationship between a cause and an effect was one of causation or simply association. This causation analysis checklist is sometimes referred to as the Bradford Hill criteria.
- Temporal relationship
- Strength
- Dose-response relationship
- Consistency
- Plausibility
- Consideration of alternate explanations
- Experiment
- Specificity
- Coherence
Medical apportionment is an estimate of the extent to which two or more probable factors caused an injury or disease. When apportioning responsibility for an injury or disease, one must first consider all potential causes and then determined whether each is probable or possible. A compensable injury or disease may exacerbate or aggravate a pre-existing condition, but may also be temporarily or partly worsened by subsequent trauma or exposure. Many illnesses are multifactorial in etiology. Physicians must be aware of the current medical literature to determine the causes for a condition, including occupational and nonoccupational causes and the significance of these causes.