Apportioning a Preexisting Condition with a New Trauma

By Richard H. Adler, Arthur D. Leritz

November 13, 2017

The phrase “preexisting condition” often causes some confusion for health care providers when they are asked to apportion a percentage of a patient’s condition between a preexisting condition and a new trauma.  The purpose of this article is to provide guidelines on when a provider needs to apportion injuries and how to do so.

As you may well know, the insurance industry would like you to believe that all conditions are related, whether they are active or not, and they won’t tell you the rules that apply in this situation.  They may even lull you into this concept by sending you a form asking you to confirm that the patient had a history of a similar condition, with the idea that if your patient is suffering from the same or even a similar condition that preexisted the trauma, they can refuse to pay for it.  What they don’t ask you to distinguish on the form, though, is whether your patient’s prior condition was active or inactive.

Under the law there are two types of preexisting conditions.  The first is known as an “inactive” or “dormant” preexisting condition.  The second is known as an “active” or “symptomatic” preexisting condition.  This is also sometimes referred to as a “latent” condition.    In the medical-legal context, the difference between an active preexisting condition and an inactive preexisting condition is, to use a cliché, “like night and day.”  For example, when treating a patient’s condition that involves a new trauma superimposed on an inactive or dormant preexisting condition, no apportionment of injuries is required.  On the other hand, apportionment of injuries/conditions is required when a patient has a new injury superimposed on an active preexisting condition.

Let’s start by defining an inactive preexisting condition.  In the context of an inactive preexisting condition, Washington law states that if there is no evidence that a preexisting condition is causing pain or disability before trauma is sustained, then the “lighting up” of that preexisting condition makes the at-fault party liable for all damages proximately caused to the injured person.  With inactive preexisting conditions, there is no prior pain or disability to differentiate from the injuries caused by the new trauma.  From the medical-legal perspective, the “proximate cause” of the present symptoms is the recent trauma, even though the symptoms may be worse or healing may take longer because of a preexisting condition.

So, what is “proximate cause?”  Proximate cause means a cause which, in a direct sequence, produces the injury complained of and without which such injury would not have happened.  Think of proximate cause like a metal chain – if the chain is unbroken by any new cause then the proximate cause is the injury producing event.

The concept of preexisting condition has been stated many times by the Washington courts, perhaps most eloquently by the Supreme Court in 1969, in the case of Bennett v. Messick.[1] In that case, the plaintiff was employed as a fruit picker.  Another employee was driving a forklift tractor and ran into the plaintiff.  There were several injuries, including an injury to the same ankle that the plaintiff had injured 40 years earlier while playing basketball.  The evidence showed that the prior injury healed normally and that the plaintiff suffered no pain or residuals in the ankle thereafter, until the tractor accident.  Testimony indicated, however, that a degenerative arthritic process was present in the left ankle, presumably caused by the basketball injury 40 years earlier.  The treating doctor testified that the second injury from the forklift tractor caused pain and limitation of motion within the ankle because it aggravated the dormant arthritic condition.  He further testified that without the tractor injury superimposed on the earlier injury, the chances were better than 50/50 that the plaintiff would never have had a medical problem with the ankle.  The court reaffirmed the applicable rule in this area, by stating:

The rule is that when a latent condition itself does not cause pain, suffering, or a disability, but that condition plus an injury brings on pain or disability by aggravating the preexisting condition and making it active, then the injury, and not the dormant condition, is the proximate cause of the pain and disability.  Thus, the party at fault is held for the entire damages as a result of the accident.

This was affirmed by the Washington Supreme Court in Harris v. Drake[2] in 2004.  In that case, Doris Drake rear ended Bradley Harris.  Mr. Harris, a painter by profession, underwent an IME and the physician determined that Mr. Harris’ shoulder impingement syndrome was not related to the collision, but was more probably than not from a preexisting condition.  Fortunately for Mr. Harris, that physician was excluded from testifying at trial.  In affirming the court’s prior ruling in Bennett, the Harris court stated:

Even allowing for the possibility of a preexisting condition, the defense failed to show that such condition was symptomatic prior to the accident.  When an accident lights up and makes active a preexisting condition that was dormant and asymptomatic immediately prior to the accident, the preexisting condition is not a proximate cause of the resulting damages.

How do you translate this rule of law into your practice? Here is what we suggest:

  1. Avoid notations in your chart notes that the patient had a degenerative condition. This will invite additional inquiries from attorneys and insurers, and create more paperwork for you regarding whether the degenerative condition is the cause of the pain or disability.  To avoid the additional paperwork and requests for clarification, remember . . .
  2. . . . that whenever discussing a preexisting degenerative condition in chart notes or narrative report, it is a good idea to add whether this condition was an active or an inactive condition prior to the collision.
  3. Inactive preexisting conditions will require no additional workup by the health care provider in apportioning injuries. Active preexisting conditions do require an apportionment opinion.
  4. If the patient does indicate that, prior to the recent trauma, they were having either restrictions on activities or motion, pain, or discomfort, we recommend you obtain a better understanding of the degree of change between the old condition and the new injury. You will likely be called upon to apportion or segregate a percentage of the patient’s condition between the old condition and new condition, or between multiple current traumas.

Apportioning a percentage of injury or residuals between an active preexisting condition and a new injury can seem an unsettling task.  Clinicians frequently describe the process as being more akin to “guesswork” than to forming an opinion that has certainty.  Though this area of opinion making may have grey zones, the law gives great discretion and latitude to the doctor.

For example, when called upon to give an expert opinion on apportionment, remember that your opinion need only satisfy the legal standard “more probably true than not.”  The opinion does not require the doctor to be “absolutely sure,” “scientifically certain,” or “positive beyond doubt.”  A more-probable-than-not standard simply means “more likely true than not.”  In other words, if you are 51 percent certain, even though you may be 49 percent uncertain, the legal standard allows you to state your expert opinion as “more probably true than not.”

Another key point to remember is that there is no formula, guidebook, or cookbook that instructs the provider as to which variable is more important than another in answering a question on apportionment of injuries.  Each case must be evaluated independently.

The following factors may be useful when assessing “how to” apportion an active preexisting condition with a new trauma:

  1. Ask Your Patient. Have your patient rate him/herself before and after the current trauma.  This can be accomplished in a number of ways.  For example, the doctor can ask the patient:
    • “Tell me, how much do you think your prior condition is responsible for your present condition and how much comes from the recent trauma?”
    • “On a scale of one to ten, with ten being the most pain, how would you rate yourself before this accident? How would you rate yourself now?”  If the patient says “2” before and “8” now, then this may mean a 20 percent to 80 percent apportionment for this one variable.  How does this blend in with the other information you have obtained?
    • “What percentage worse are you now from the recent motor vehicle accident?
  2. “But for” Test.  Ask yourself and ask your patient:
    • “But for this new trauma, how much longer would he/she need treatment?”
  3. Pain Questionnaire. Many providers are using pain questionnaires to assist them in monitoring the progress of patient care.  What restrictions on activities or pain problems did your patient report before the new trauma?  Administer a “like-kind” questionnaire after the new trauma and compare the results.
  4. Prior Records Evaluation. If your patient was treating with other providers prior to the new trauma, attempt to obtain and review those records to help you assess the level of symptoms, frequency of care, and treatment plan.
  5. Patient History. It is a good idea to obtain a comprehensive history from your patient about the degree of symptomatology, restrictions on activities, residuals, frequency of treatment, etc., just prior to the present trauma.  Asking the patient to complete a pain questionnaire based on how he or she was doing before the recent trauma, will provide you insights.
  6. New Injuries. Did the recent trauma cause new injuries in addition to aggravating the old condition?  Which injuries are more significant to the patient, the new ones or the prior, aggravated condition?  Compare old x-rays with a more recent series.  Are there any differences between the active preexisting condition and the new trauma?  What are the differences
  7. Prognosis.  What was the prognosis just before the recent trauma?  How has that prognosis changed?  Can you quantify that?

We hope this article provides some useful insights on the medical-legal context of preexisting conditions and apportionment of injuries.  As always, if we can be of any assistance to you, your staff, or your patients concerning personal injury issues, please do not hesitate to contact our office.


[1] The legal citation for this case is 76 Wn.2d 474 (1969).

[2] The legal citation for this case is 152 Wn. 2d 480, 99 P.3d 872 (2004).