Ask a doctor if they can be sued for what might happen in the future, and they likely will say, “Of course, it happens all the time!” Most doctors have some version of the, actually apocryphal, story of an obstetrician who was sued when a child they delivered could not get into a top university 17 years later.

The reality, though, is that an essential point of tort law is that damages must be provable at the time of the lawsuit. This is because the objective of the lawsuit is to make the plaintiff whole, not to make them better off than they would have been by piling on what may happen in some attenuated fashion in the future. Damages that derive directly from the malpractice and are certain but will only accrue in the future–such as the need for permanent supportive care that a brain-damaged child will have or the economic losses to a truck driver who is now blind in one eye due to botched cataract surgery and can no longer qualify for a license–must be proven by expert testimony and assigned an actual dollar value.

However, there is a countervailing doctrine that does address the future and what only may occur as the consequence of malpractice, and doctors should be aware of it: “loss of chance.”

A typical example would be a radiologist who is sued by a patient who claims that a mammogram the doctor read 2 years ago showed a small early cancer that was not diagnosed, and that she was therefore at stage IIIa disease, with a tumor over 2 cm and four positive lymph nodes, at the time of her diagnosis rather than at stage I. She is currently cancer-free, but in addition to her damages for the more extensive treatment that she needed, she is alleging a decrease in her chance to survive.

So, how can a currently healthy plaintiff sue for an outcome (death from cancer) that is only possible?

The answer is that she is not suing for a future damage; she is suing for one that has already accrued: the loss of a substantial chance to be cured.

“Loss of chance” is not a new doctrine.  In fact, it goes back to the 19th century, when in 1867, the Ohio Supreme Court held that “any [negligence]…which diminishes the chances of the patient’s recovery… would, in a legal sense, constitute injury.”

Then, in 1902, a Kentucky appellate court held that “the patient is entitled to the chance for better results…That the patient might have [suffered the same outcome] in spite of [proper] treatment, or that ordinarily [bad results occur]…is no excuse to the physician who neglects to give his patient the benefit of the chance.”

In 1966, in Hicks v. United States, the 4th Circuit stated that “When a defendant’s negligent action or inaction has effectively terminated a person’s chance of survival, it does not lie in the defendant’s mouth to raise conjectures as to the measure of the chances that he has put beyond the possibility of realization. If there was any substantial possibility of survival and the defendant destroyed it, he is answerable.”

The doctrine became accepted because it fits the preference that courts have for negligent parties fully compensating those they have harmed, the wholeness of the plaintiff that is sought to be rendered necessarily also encompassing their prognosis.

It is now widely applied. Although most cases are, like the breast cancer example above, about delays in diagnosis, “loss of chance” has also underpinned claims for failure to timely call emergency services, failure to timely admit to a hospital, failure to properly or timely transfer a patient, and failure to perform needed surgery.

It has also evolved over time in the interests of fairness. The rule used to be that the pre-negligence survival had to be expected to be more likely than not (ie, >50%), which is the standard to find negligence. Any harm that a plaintiff with a poorer prognosis suffered was just attributed to their disease, even if the doctor was found to have been negligent. However, this meant that doctors who happened to have been negligent on patients with worse illnesses were de facto protected. Courts, therefore, began to separate causation from damages.

As explained by the Supreme Court in Massachusetts, if a physician’s breach of duty eliminated or diminished the patient’s chance of survival or of a better outcome, that physician had “deprived the patient of something of value.” Courts in many states have, using that analysis, therefore, rejected the greater than 50% cut-off and now identify that the loss of a chance for a better outcome or a cure is actually a damages issue that is gradable on its own value, just as would be, for example, the loss of a chance to make a living due to the malpractice.

Of course, even in states that have adopted the more flexible version, there are countervailing limits.

A claim of “loss of chance” must rely on expert evidence and must follow established parameters, such as overall survival rates and survival rates at standard intervals. The expert must testify as to their specific methodology and as to the reliability (as supported by peer-reviewed research) of their opinion that there was a loss of chance and of what degree.

Further, statistics alone do not satisfy the plaintiff’s burden of proof as to whether there was a loss of chance. The expert must show that the probability of recovery of that individual plaintiff, taking into account their overall health and the specific nature of the disease, falls within the statistical range quoted for patients with that condition.

This is not, however, a requirement to prove that the plaintiff would definitely have done better without the negligence. As the 4th Circuit wrote in Hicks, “Rarely is it possible to demonstrate to an absolute certainty what would have happened in circumstances that the wrongdoer did not allow to come to pass. The law does not in the existing circumstances require the plaintiff to show a certainty that the patient would have lived had she been hospitalized and operated on promptly.”

In other words, what the plaintiff needs to prove as a threshold matter is that they were within a group likely to have done better by the amount of the lost chance.

The lost chance must also then be proven to be “substantial,” and that can be a complicated matter.

That issue was previously solved by the strict greater than 50% rule, but in states that have abandoned it, courts have not placed a different numerical value on what is deemed “substantial.”

This is actually medically realistic; after all, a 20% loss of chance is far worse when it drops from a 30% chance to a 10%  compare with when it decreases from a 70% chance to a 50%.

Ultimately, it will be case-specific and a matter for the jury. The expert will opine on a general loss of chance, but it is the jury that determines what role it really played in the context of the disease as it was at the time of the claimed negligence. For example, a 20% loss of chance due to a failure to diagnose an infant’s tumor that decreased her chance of survival from 60% to 40% was held to be substantial in Minnesota, whereas a 14% reduction of likely survival in a lung cancer case was accepted as substantial in Washington.

This is, of course, the point at which the defense will be pushing back and claiming that the disease itself overshadowed the effect of the claimed malpractice, in essence seeking to convince the jury of what the older rule simply took as a given: that below a certain level of survivability, disease pathology overshadows the effect of negligence.

The defense will also address several points to give the jury perspective on the role that a delay may have actually had in the outcome:

• Unduly high expectations: Jurors who themselves have been advised to have screening tests likely believe that earlier detection always leads to cure, so a poor outcome would be solely due to the negligence, and so the defense will focus on the intrinsic limitations created by the disease itself.
• Lead time bias: Earlier diagnosed cases appear to survive longer, so the defense will counter population statistics with where the plaintiff actually was in their own condition at the time that the alleged negligence occurred.
• Staging is not a date issue: The defense will emphasize the fact that staging is intended to be used for medical treatment decisions and is not a calendar marker.

If a loss of chance is found, damages can be set in one of two ways. In the first, the injury or death is seen as the compensable harm, so full damages are recoverable regardless of the actual percentage loss of chance. In the second, there is recovery for only the value of the reduction of the chance of survival or better outcome.

In summary: 

The “loss of chance” doctrine allows the plaintiff to be compensated for a substantial loss of a better outcome due to medical negligence. This level may be fixed at greater than 50% or be a matter for the jury. This is not a speculative damage, because it has already accrued, even though it may play out over time. To prove that the doctrine applies, the plaintiff must prove that they are part of a population likely to have benefitted from earlier care, while the defendant will emphasize the disease pathology as being the dominant feature. Damages may be complete or be scaled to the percentage of lost chance.