Determining Causation in Workplace Injuries – Q1 2023

Max Lebow, MD, MPH, FACEP, FACOEM Section Editor, Occupational Medicine

Not every employee’s injury or illness is considered related to their employment. One of the unique challenges for the Occupational Medicine provider is determining whether their patient’s injury is related to their work – often a non-clinical decision. Causation determination has repercussions in most aspects of the patient’s case from that point forward.

How Causation Determination Impacts the Workplace Injury/Illness.

  1. Causation Determines Treatment Location – Care providers with some Work Comp experience may treat work-related injuries. Non-work-related injuries will be treated by the patient’s Primary Care Provider, although a few states also allow the patient’s primary physician to be their occupational physician.
  2. Causation Determines Outcome – Work-related injuries can take up to three times longer to resolve than non-work-related injuries. 
  3. Causation Has a Direct Economic Impact on the Patient – Employees may collect Workers’ Compensation benefits to replace lost income during recovery if the injury is deemed work-related.
  4. Causation Has an Economic Impact on the Employer – Increasing the employer’s insurance rates and other indirect negative economic impacts.

Determining Causation

Determining causation is usually straightforward. For example, a butcher who sustains a finger laceration by a meat slicer leaves little question as to the work-relatedness of the injury. However, more complex cases, such as patients with pre-existing medical conditions who have a flareup at work or an injury that occurs off-site, may require the provider to understand OSHA guidance and their state legislation to help make the correct causation decision.

OSHA 1904.5: Determination of Work-Relatedness (State OSHA programs often mimic US OSHA)

OSHA states that an injury is work-related if the event or exposure is caused or contributed to the resulting condition or significantly aggravates a pre-existing injury or illness, and exemptions do not apply. These OSHA exemptions (most applicable) include:

  • An illness that surfaces at work but results solely from a non-work-related event or exposure.
  • Injury or illness results solely from voluntary participation in a wellness program, medical, fitness, or recreational activity such as blood donation, flu shot, or exercise class.
  • Illness solely the result of an employee eating, drinking, or preparing food or drink for personal consumption (unless contaminated by toxic workplace materials).
  • Injuries caused by an MVA while the employee is commuting to or from work.
  • Common cold or flu. (Note: contagious diseases such as tuberculosis, brucellosis, hepatitis A, or plague are considered work-related if the employee is infected at work.)
  • Mental illness — although there are many steps. We will explore stress and PTSD in the workplace in a later article.

Concept of AOE/COE

Another way to approach work-relatedness is consideration of AOE/COE or Arises Out of Employment and in the Course of Employment. 

Arises Out of Employment (AOE) is determined by the treating provider. After a history and physical, the provider must factor into the assessment the mechanism of injury, the patient’s job description, and the relationship between workplace risk and the resultant injury or illness. In many states, the physician will then be asked to determine, within Reasonable Medical Probability or more likely than not, that the patient’s injury is or is not work-related. Some states will then consider a percentage of contribution. In California, for example, the work injury need only contribute to 1% of the patient’s disability to be compensable.

COE-Occur in the Course of Employment is a more complex assessment often determined in a medical-legal environment. This considers factors such as where the injury occurred and whether the employee was doing work that contributed to their employer or on behalf of their employer.

Aggravation of a Pre-Existing Medical Condition.

An aggravation/exacerbation determination is whether a workplace injury/exposure worsened a patient’s pre-existing medical condition, either temporarily or permanently. This often requires the provider to review past medical records and previous treatments and other risk factors. To many occupational medicine physicians, this is the most difficult determination.

Determining aggravation is more difficult when the pre-existing medical condition is a previous work-related injury. Determining if the current incident represents a new injury, is an aggravation of a previous injury, or is unrelated to work can be a difficult but impactful decision.

The Importance of a Complete and Thorough History in Causation Determination

From the previous discussion, it is easy to see that a standard Urgent Care history is inadequate to communicate causation determination. While some cases are obvious, all patient charts should document enough information to establish the temporal relationship to the patient’s injury, a detailed mechanism of injury, and whether other causes may explain the patient’s pain or functional impairment.

This article represents an introduction to occupational medicine causation determination. The work-relatedness of psychological impairments such as stress and PTSD will be the subject of a future discussion.

You can reach Dr. Lebow at:

Medical Director | Board Certified in Occupational Medicine and Emergency Medicine
Reliant Immediate Care Medical Group, Inc.
Insight Practice Partners RCM, Inc. 
(o) 310.215.6020 |