Descriptive, Predictive Data at Odds in Medical Malpractice Courtroom

Because they're busy looking in different directions, "innocent until proven guilty" and "first, do no harm" don't always get along.

One day in November 1987, Ernest Kunnanz went to the emergency department with an excruciating pain in his side. The physicians examined him and quickly came to a diagnosis. Even a medical student would have recognized the telltale combination of colicky back pain and costovertebral angle tenderness. Mr Kunnanz had a kidney stone.1

Mr Kunnanz was referred to Stephen L. Edge, a urologist, who recommended a uteroscopy to remove the stone. The operation did not go well. Dr Edge’s operative report noted that Mr Kunnanz’s ureter was extremely narrow and that multiple dilations were required to pass the ureteroscope up to the renal pelvis. During this process, the kidney stone was pushed up the ureter and into the kidney, where it could not be removed. Dr Edge placed a ureteral stent, which he removed 2 weeks later.

Three weeks later, Mr Kunnanz’s condition had not gotten much better, and Mr Kunnanz went to another urologist for a second opinion. A follow-up ureteroscopy revealed 2 perforations and a submucosal fistula in Mr Kunnanz’s upper ureter. The kidney and ureter had been irreversibly damaged. Approximately 5 months after his initial visit to the hospital, Mr Kunnanz had surgery to remove the compromised kidney and ureter.

Not long after that final operation, Mr Kunnanz sued for medical malpractice, claiming that — among other things — Dr Edge had negligently performed the initial ureteroscopy. The critical question, as is typical of malpractice cases, was whether Dr Edge had breached the standard of care and caused Mr Kunnanz’s injury. During the trial, the plaintiff’s attorney got right to the heart of the matter. He asked the expert witness: “Did Dr Edge’s failure to follow accepted standards proximately cause the loss of Mr Kunnanz’s kidney?”

The defense lawyer raised an objection, and the judge sustained it. The witness was never allowed to answer the question.2

There are 2 kinds of data in the world: descriptive and predictive. The difference between them is what the names indicate: descriptive data tell you what happened in the past, whereas predictive data give some idea as to what might happen in the future. A descriptive figure is how many people contracted H1N1 influenza last year; a predictive one is the probability that H1N1 will be the dominant strain next season. One looks back, the other looks forward.

There is the same sort of distinction between the way that lawyers and doctors think about malpractice issues. Lawyers (and judges and juries and the rest of the legal system) are focused exclusively on figuring out what exactly happened in the case being tried. There’s not too much weight given to how likely the outcome was or whether it’s bound to happen again. Those notions are considered too speculative to tell us definitively what happened on the day in question. Stepping into the courtroom seems to turn everyone into Joe Friday: just the facts, ma’am.

Physicians, on the other hand, take a more expansive view. We’re not concerned with just 1 case. We’re trying to optimize performance over hundreds, if not thousands, of interactions. We have the luxury — or perhaps the obligation — to recognize that any given outcome, good or bad, might just be good (or bad) luck, and it’s what happens over the course of a larger sample size that truly counts. That’s true whether we’re talking about which patients are at greatest risk for receiving negligent treatment, or what insurance rates should be, or which physicians might benefit from remediation. It is evidence-based practice in action. Everything is future oriented.

The guiding principle of the courtroom is “innocent until proven guilty,” which is pretty stern guidance on how to think about an event that’s already come and gone. Physicians, meanwhile, are guided by the tenet “first, do no harm” — a hopeful prediction for the future. 

Because they’re busy looking in different directions, “innocent until proven guilty” and “first, do no harm” don’t always get along. The conflict is especially acute in the context of how malpractice trials handle evidence that the defendant physician had previous instances of failing to meet the standard of care. Physicians understand this to be powerful data: those who have had malpractice events in the past are likely to have more in the future, a very small percentage of physicians account for a staggering portion of patient claims, and so on. The analysis deserves some nuance and risk adjustment, but it’s certainly reasonable to think that individualized malpractice data can point the assessment of a physician’s performance in the right direction. Data are a powerful predictive tool.

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Yet that information rarely sees the inside of a courtroom. The rules of evidence that govern what testimony juries and judges can consider frame malpractice history as more likely to poison the well than uncover the truth.3 The crux of the problem, from the legal standpoint, is that, regardless of what a series of old malpractice claims might say about a physician’s tendencies, they don’t directly speak to what happened in the particular case before the bar. The data are descriptive, the courts seem to acknowledge — but the data are not descriptive of the right thing. 

In reality, all data are both descriptive and predictive, depending on how they are used; the distinction is entirely contextual. Malpractice data are not useless in the courtroom just because the data cannot prove definitively whether the standard of care was breached in any given case. The data can still describe accurately what happened in the past, and it can also make probabilistic assessments about the likelihood of similar events occurring going forward. Judges and juries should never be compelled to find a verdict solely on the basis of this evidence, but it is unclear what harm would result from allowing them to consider and balance it against all the other information presented at trial. “Innocent until proven guilty” and “first do no harm” are both valuable conceits. Why ignore either of them?

About a week before Mr Kunnanz went to the emergency department because of his kidney stone, Dr Edge performed a ureteroscopy on another patient, Cathy Kunkel.1 It didn’t go well, either. Much like Mr Kunnanz, Ms Kunkel’s ureter was perforated and she ended up having to have her kidney removed. She later sued Dr Edge for negligence and settled out of court. At Mr Kunnanz’s trial, his lawyers attempted to introduce evidence of Dr Edge’s mishandling of the Kunkel case, but the rules of evidence prohibited it. Whatever insights the Kunkel affair might have held never reached the jury’s ears, ensuring that that data were neither descriptive nor predictive. 

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  1. Kunnanz v. Edge, 515 N.W.2d 167 (N.D. 1994)
  2. Ginsberg M. Good medicine/bad medicine and the law of evidence: is there a role for proof of character, propensity, prior bad conduct in medical negligence litigation? South Carolina Law Review. 2011;63.
  3. Rule 401. Test for relevant evidence. Pub. L. 93–595, §1 (2011).

This article originally appeared on Medical Bag