"Causal Relationship"

Causal relationship involves establishing a connection between the condition -- ie. injury -- and your employment. This factor is based entirely on medical evidence provided by physicians who have examined and treated the employee. Opinions of the employee, supervisor or witness are not considered, nor is general medical information contained in published articles.

A. Kinds of Causal Relationship. An injury or disease may be related to employment factors in any one of four ways:

(1) Direct Causation. This term refers to situations where the injury or factors of employment result in the condition claimed through a natural and unbroken sequence.

(2) Aggravation. If a pre-existing condition is worsened, either temporarily or permanently, by a work-related injury, that condition is said to be aggravated.

(a) Temporary aggravation involves a limited period of medical treatment and/or disability, after which the employee returns to his or her previous medical status. Compensation is payable only for the period of aggravation established by the medical evidence, and not for any disability caused by the underlying disease. This is true even if the employee cannot return to the job held at time of injury because the pre-existing condition may be aggravated again. For example, if exposure to dust at work temporarily aggravates an employee's pre-existing allergy, compensation will be payable for the period of work-related disability but not for any subsequent period, even though further exposure in the work place may cause another aggravation.

(b) Permanent aggravation occurs when a condition will persist indefinitely due to the effects of the work-related injury or when a condition is materially worsened by a factor of employment such that it will not return to the pre-injury state.

(3) Acceleration. A work-related injury or disease may hasten the development of an underlying condition, and acceleration is said to occur when the ordinary course of the disease does not account for the speed with which a condition develops.

(4) Precipitation. This term refers to a latent condition which would not have manifested itself on this occasion but for the employment. For example, an employee's latent tuberculosis may be precipitated by work-related exposure.

B. Medical Evidence. The issue of causal relationship almost always requires reasoned medical opinion for resolution. This opinion must come from a physician who has examined or treated the employee for the condition claimed. Where a pre-existing condition involving the same part of the body is present, the physician must provide rationalized medical opinion which differentiates the effects of the employment-related injury or disease from the pre-existing condition. Such evidence will permit the proper kind of acceptance (temporary vs. permanent aggravation, for instance).

To establish causal relationship, additional medical opinion may be requested of OWCP's District Medical Director/Adviser or from a specialist in the medical field pertinent to the injury or disease. In a claim for a psychiatric condition, a report from a psychiatrist or clinical psychologist will be required. In claims for hearing loss and pulmonary disease, OWCP will refer the employee for examination by an appropriate specialist after exposure to the hazardous condition or substance has been established. Chapter 6 contains further information about medical examinations.

C. Consequential and Intervening Injuries. Sometimes an injury occurring outside the performance of duty affects the compensability of a work-related injury.

(1) A consequential injury is a new injury which occurs as the result of a work-related injury (for example, because of weakness or impairment caused by a work-related injury). Included in this definition are injuries sustained while obtaining medical care for a work-related injury. Consequential injuries are compensable.

(2) An intervening injury is one which occurs outside the performance of duty to the same part of the body originally injured. The resulting condition will be considered related to the original injury unless the second injury and any other factors unrelated to the original injury are established as its cause.

For instance, an employee with an accepted claim for back strain later begins to have pain which suggests disc involvement. Later, while at home, he suffers pain in his back when he leans over the tub to clean it. Unless the incident at home is medically competent to cause the resulting condition, and it breaks the chain of causation of an earlier injury, OWCP will consider the resulting condition to be causally related to the original injury.

Information taken from the Publication CA 810