Under apportionment, which factor is used to determine allocation among conditions?

• A. Medical report
• B. Causation
• C. Pathology
• D. Preexisting condition

Answer: (B)

Causation determines how you allocate impairment among multiple conditions. When more than one condition is involved, the amount of disability or costs assigned to each condition is based on the causal contribution of that condition to the overall impairment. Medical evidence, including reports and tests, is used to establish how much each condition was caused or aggravated by the work-related event, and then that portion of disability is attributed accordingly. Pathology describes tissue changes and informs the investigation, but it’s the determination of whether the work event caused or contributed to each condition that drives the apportionment. A preexisting condition may influence the attribution, but the key factor in dividing the allocation is the causal relationship to the work-related injury.