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Malpractice Issues in Radiology |
1 Department of Radiology, Rush North Shore Medical Center, 9600 Gross Point Rd., Skokie, IL 60076; and Rush Medical College, Chicago, IL 60612.
Received January 21, 2000;
accepted after revision February 24, 2000.
Case summaries are based on actual events and lawsuits, although certain
facts have been omitted or modified by the author, who has supplied and
obtained authorization for the reproduction of the radiologic images. All
opinions expressed herein are those of the author and do not necessarily
reflect those of the American Journal of Roentgenology or the
American Roentgen Ray Society.
Introduction
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Notwithstanding treatment with surgery, chemotherapy and radiation, the patient's clinical condition steadily deteriorated. He died 16 months after the diagnosis had been established.
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The defense attorney showed the original chest radiographs to several radiology experts and sought their opinions about whether the defendant radiologist's interpretation of them conformed to the standard of care. The experts responded that once they had seen subsequent radiographs that showed the large tumor mass, they knew exactly where to look and, therefore, could retrospectively find a density on the original radiographs that probably represented the tumor. However, the experts believed that because of the subtlety of the findings and the fact that the defendant radiologist had no knowledge of subsequent radiographs at the time of initial interpretation, his reporting of normal findings on chest radiographs had conformed to the standard of care. In the meantime, the defense attorney was informed that the attorney for the plaintiff had retained radiology experts who believed that the tumor was obvious on the original radiographs and that the defendant radiologist's failure to see and report the abnormal finding constituted negligence.
As initial discovery proceedings began, the defense attorney decided to focus on two major issues: frequency of perceptual errors among radiologists and the influence of hindsight bias. With regard to errors, the radiology experts who had been consulted by the defense attorney called attention to the many articles published in the radiology literature that indicated that perceptual error rates of radiologists hovered in the 30% range [1,2,3,4]. One study the defense attorney found particularly appropriate under the circumstances was a study conducted by researchers at the Mayo Clinic, which found that up to 90% of lung carcinomas that were eventually diagnosed on radiographs could be seen on retrospective review of chest radiographs initially interpreted as showing normal findings [5]. If perceptual errors were that common among radiologists, wondered the defense attorney, could the alleged interpretive error made by the defendant radiologist in this case truly be considered negligence?
The second issue dealt with the opinions of the radiology experts retained by the plaintiff that the defendant radiologist had been negligent by missing the tumor on the initial chest radiographs. Was it likely, as had been suggested by the radiology experts consulted by the defense attorney, that the tumor on the original radiographs became obvious only after the subsequent radiographs had been reviewed? What perplexed the defense attorney was the fact that on one hand the law required a radiologist to exercise the degree of skill and care expected of a reasonably prudent radiologist acting in the same or similar circumstances at the time the care in question was rendered, while on the other hand radiology experts for the plaintiff were basing their opinions solely on their review of the initial radiographs after they had full knowledge that the radiographs obtained 3.5 years later showed an obvious tumor. The defendant radiologist was being accused of negligence because of an alleged misinterpretation of chest radiographs that had been rendered prospectively and without any knowledge of what future radiographs would disclose, and yet he was being judged by radiology experts who had full knowledge of what the future radiographs actually did disclose. Thus, concluded the defense attorney, because the same or similar circumstances at the time the care in question was given could never be reproduced, evaluation by retrospective review could never be accurate.
With these concepts in mind, the attorney for the defense commenced discovery proceedings determined to have all the radiology experts, whether retained by the attorney for the plaintiff or the attorney for the defense, concentrate on the issues of error rates and hindsight bias. However, at deposition the radiology experts retained by the plaintiff held firmly to the opinion that the tumor on the initial chest radiographs was so large and obvious that the defendant radiologist's failure to see and report the lesion was a clear breach of the standard of care. Radiology experts retained by the defense held firmly to the opposite view, stating that the mass, even if discernible on the initial chest radiographs, was so subtle and inconspicuous that failing to observe and report it did not constitute negligent conduct. With neither side retreating from its position, resolution by settlement was never seriously entertained by either party. The lawsuit thus proceeded to a jury trial [6].
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The second expert radiology witness for the plaintiff agreed, adding that "They pay us to find a mass like that and it should never have been missed." The witness went on to explain that it might still be within the standard of care for a radiologist to occasionally miss a "peasized or even a Lifesaver-sized lesion," but any radiologist who misses a tumor the size of a "grapefruit, baseball, or golf ball" would fall below the standard of care. "If I have to keep looking and looking at a film until I see something, then a radiologist might miss the finding and still be within the standard of care," opined the expert for the plaintiff. "However," continued the expert, "I had no difficulty in seeing the mass on both views immediately, and therefore the defendant radiologist who missed the tumor was negligent. If I had missed that mass," added the expert, "I also would have fallen below the standard of care."
During cross-examination of the expert witnesses for the plaintiff, the defense attorney focused on the issues of error rates and the phenomenon of hindsight bias. One of the plaintiff's radiology experts rejected the applicability of the case being tried to published studies regarding radiology error rates because all the pertinent published articles dealt with lung cancers only and not thymomas. Another plaintiff's expert likewise dismissed the validity of published studies regarding missed lung lesions, asserting that these studies dealt with masses considerably smaller than 3 cm, whereas in the present case the tumor that was missed "measured at least 3 cm."
The radiology experts for the plaintiff also flatly rejected the suggestion of the defense attorney that knowledge of what was found on subsequent radiographs biased their opinions about whether the defendant-radiologist's missing of the tumor on the initial radiographs was due to negligence. Each of the experts claimed that they had reviewed the initial radiographs before they had looked at subsequent studies and before they had been told that the case centered on an alleged missed lung tumor. "But didn't you surmise that if an X ray was brought to you for review by an attorney, that X ray would necessarily be abnormal?" asked the defense attorney. "Not at all," answered one of the radiology experts retained by the plaintiff. "The lawyer could well bring normal radiographs."
As expected, the radiology experts retained by the defense testified quite differently. As to the question of whether the defendant radiologist had been negligent in his interpretation of the initial chest radiographs, each of the defense experts testified that the defendant had not. Each claimed that the tumor was barely evident and could well have been taken for normal structures by a reasonable radiologist. Regarding the claim that articles published in the radiology literature documenting error rates among radiologists did not apply to the case being tried because the errors dealt with lung carcinomas rather than thymomas, one defense expert called such a contention "silly."
"A thymoma looks no different to a radiologist than a carcinoma," explained the defense expert, "and radiologists deal with shadows and densities, not with cell types. Differentiation of tumor type is made by the pathologist, not the radiologist." This defense expert did acknowledge, however, that published studies showing that an error rate of 30% among radiologists did not necessarily mean one can conclude that a single error committed by a particular defendant radiologist could not have been the result of negligence. The radiology expert agreed that every case in which a missed diagnosis was alleged must be considered individually and on its own merits.
Another radiology expert for the defense took issue with the plaintiff's premise that only the size of a missed tumor determined whether or not a radiologist was negligent. The expert went on to explain that conspicuity is determined by a combination of factors such as size, density, location, and overlying structures, not by any one of the factors alone. The defense expert used the analogy of a night sky to explain conspicuity:
If the air is clear and the sky is totally black because the moon is not visible, even the smallest star will be readily visible to the eye. However, if the sky is partially illuminated by the moon, or if there are small clouds present, the tiniest stars will no longer be seen but the medium and large ones will. If the sky is further illuminated or thicker clouds emerge, then even the largest stars will not be discernible.
As to whether hindsight bias influences a radiology expert's opinion regarding radiographs brought by an attorney for review, one of the defense experts asserted that it certainly did. "I've never had an attorney bring me a normal radiograph," testified the expert. "Whenever an attorney shows or sends me radiographs, the first and only question that comes to my mind is, what was missed on these films?"
At the conclusion of the trial, the opposing attorneys gave their final arguments to the jury, each emphasizing those portions of the conflicting expert witness testimony that supported his position. After 3 hours of deliberation, the jury found the defendant radiologist liable for malpractice by a 10-to-2 vote, and awarded $872,000 to the family of the deceased patient.
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As to the relationship between viewing time and probability of error raised during the trial by one of the plaintiff's radiology experts, the data are conflicting. Researchers at the University of Missouri in 1976 found that in cases in which radiologists missed findings, the average viewing time was 147 sec, whereas in cases in which radiologists reached a correct diagnosis, the average viewing time was 113 sec [8]. The findings of the Missouri researchers supported the observation that radiologists' confidence in the accuracy of their opinions vary inversely with the length of their reports. More than a dozen years later, however, Oestmann et al. [9] described contradictory results: accuracy of interpretation diminished as viewing time decreased. In their study, radiologists found 30% of "subtle" lesions in 0.25 sec of viewing time, but the number of lesions identified increased to 74% with unlimited viewing time. Radiologists found 70% of obvious carcinomas in 0.25 sec of viewing time, and this number increased to 98% with unlimited viewing time. The detectability of lesions decreased considerably as viewing time became less than 4 sec.
To what extent the missing of a lung lesion constitutes negligence remains as unclear today as it was 105 years ago when Roentgen discovered X rays. A recent decision rendered by an appellate court in Wisconsin sheds some light on this somewhat blurry distinction [10]:
The radiologist's] having failed to perceive defects that could have been perceived in radiographs does not establish that he failed to conform to acceptable standards of practice in the manner in which he read them... In determining whether a physician was negligent, the question is not whether a reasonable physician, or an average physician, should have detected the abnormalities, but whether the physician used the degree of skill and care that a reasonable physician, or an average physician, would use in the same or similar circumstances... A radiologist may review an x-ray using the degree of care of a reasonable radiologist, but fail to detect an abnormality that, on average, would have been found... Radiologists simply cannot detect all abnormalities on all x-rays... The phenomena of "errors in perception" occur when a radiologist diligently reviews an x-ray, follow[s] all the proper procedures, and use[s] all the proper techniques, and fails to perceive an abnormality, which, in retrospect is apparent... Errors in perception by radiologists viewing x-rays occur in the absence of negligence.
Notwithstanding this formal opinion of the Wisconsin court, from a practical point of view once an abnormality on a radiograph is pointed out and becomes so obvious that lay persons sitting as jurors can see it, it is not easy to convince them that a radiologist who is trained and paid for seeing the lesion should be exonerated for missing it. This is especially true when the missing of that lesion has delayed the timely diagnosis and the possible cure of a malignancy that is eventually fatal [3].
A major portion of the trial testimony in this case centered on the effect on the opinions of the radiology experts of the phenomenon known as hindsight bias. Hindsight bias is the tendency for people with knowledge of the actual outcome of an event to believe falsely that they would have predicted the outcome [11]. A classic experiment that shows how hindsight bias influences medical decisions was undertaken by a team of psychology researchers [12]. Seventy-five practicing physicians were divided into five equal groups, given the same medical case history, and then asked to assign a probability estimate to each of four possible diagnoses. The case was that of a young man who had developed pain and swelling in his knee and had undergone laboratory tests and joint fluid aspiration, the results of which were listed. The physicians in every group were asked to assign to each of four possible diagnoses (Reiter's syndrome, poststreptococcal arthritis, gout, serum hepatitis in preicteric phase) the probability that each diagnosis was the correct one. Four groups were referred to as the "hindsight" groups because in addition to receiving the basic case history, each of the groups was given additional opening sentences. The opening sentence in group 1 stated that it was a case history of Reiter's syndrome, the opening sentence for group 2 was that it was a case of poststreptococcal arthritis, and the opening sentences in groups 3 and 4 indicated that these were cases of gout and hepatitis, respectively. The second sentence in the medical case histories given to these four groups included a plea for independent assessments regardless of the preestablished diagnosis. The physicians in the fifth group, referred to as the "foresight" group, were presented with the same case history but without any indication of an established diagnosis.
The researchers found that the physicians exhibited considerable hindsight bias, but the bias was restricted to the two diagnoses assigned the lowest probability estimates by the foresight group—poststreptococcal arthritis and hepatitis. Indeed, the hindsight groups indicated that these two diagnoses were two to three times more likely to be the correct diagnosis than did the foresight group. These researchers emphasized that even though physicians are much better equipped to make informed decisions in medical matters than average people making decisions in their everyday lives, physicians remain nonetheless greatly susceptible to bias in their judgments. The researchers further explained that hindsight bias is an extremely compelling influence in the population and that people, like the physicians in this study, try to make sense out of what they know has happened rather than analyzing the available data independently. This leads, concluded the researchers, to overconfidence among physicians in assessing their own diagnostic accuracy and inadequate appreciation of the original difficulty in making diagnoses.
The exact mechanism by which hindsight bias influences judgment has been termed by one researcher as "creeping determinism," which is defined as a process in which outcome information is immediately and automatically integrated into a person's knowledge about the events preceding the outcome [11]. The process is hypothesized to be fast and below the person's level of awareness, and, thus, the outcome knowledge "creeps" into the subject's mental representation of events. Although most people are not consciously aware that they are being influenced by hindsight bias, some achieve secondary gain from the bias. One psychology researcher attributes the subconscious need for bias to motivations of wanting to appear intelligent and knowledgeable, wanting to be able to accurately predict the future because of a desire to be dogmatic and intolerant to ambiguity, and wanting to maintain a high level of public esteem (Harley E, unpublished data).
Hindsight bias is not supposed to exert influence on the determination of medical negligence. When beginning deliberations over evidence in malpractice cases, jurors are instructed to consider only whether the actions of the physician conformed to the standard of care, not whether damages occurred [13]. Even if a patient is badly injured or dies, the law holds that the injured party cannot recover damages from a physician if the physician has met the objective standard of care. However, a study conducted by two psychologists at the University of Pennsylvania indicated that the determination of negligence is influenced by whether the patient has sustained damages or harm [13]. Nonetheless, as one legal observer has pointed out, although our legal system promises not to hold defendants liable if they have conducted themselves reasonably before an injury occurs, hindsight bias ensures that some reasonably acting defendants will be unfairly subjected to adverse liability judgments when after-injury evaluation has taken place [14].
Franken [15] wrote that it is very difficult to objectively judge original radiologic interpretations retrospectively. This sentiment was echoed and then enlarged on by Berbaum [16]:
The information available within the radiograph interpreted by the retrospective reader is not the same as when interpreted by the earlier reader. The retrospective reader frequently has access to information regarding the patient's subsequent clinical course, including later radiographs demonstrating more advanced disease. Such information improves the observer's ability to perceive subtle abnormalities on a previously obtained radiograph... Perception is better if you know where to look and what to look for... We have little conscious awareness of how various sources of information are used and combined in the process of perception. It may not be possible for a retrospective reader to tell when subsequent clinical information or radiologic studies influence his or her perception of an earlier study. In general, people expect others to see what they themselves can see.
Although most radiologists may not be aware of it, hindsight bias in one form or another often plays a role to good advantage in the everyday practice of radiology in that radiologic accuracy is improved. Consider the scenario in which follow-up radiographs are taken after a patient has been diagnosed with a specific carcinoma, infectious process, or other disease. The radiologist's interpretation of the follow-up radiographs will undoubtedly be more precise once the radiologist possesses knowledge of the correct diagnosis. Elmore et al. [17] have shown how hindsight bias influences mammographic interpretations by studying the effects on the radiologist's thought processes of extraneous information such as patients' histories. These researchers found that recommendations for appropriate further diagnostic workup were altered by a patient's alerting history such as breast symptoms or family history of breast cancer. Even though the mammographic findings were objectively similar, a nonalerting history led to fewer recommended workups. These researchers also showed that when a sham clinical history was given, 40% of the radiologists changed their diagnostic interpretation about whether to recommend a biopsy in the direction of the misleading suggestion.
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As has been stated [4], the question of whether a missed radiologic diagnosis constitutes malpractice has confounded medical and legal professionals for decades, and it is not likely that the question will be resolved to the satisfaction of anyone in the foreseeable future. In the meantime, radiologists continue to be subjected to malpractice litigation more for missing radiographic diagnoses than for any other reason.
It is, of course, difficult to defend a radiologist who has failed to perceive a radiologic abnormality that in retrospect can be perceived. Nonetheless, certain defense-supporting data are available that, at times, may be offered to a jury to achieve a verdict favorable to a defendant radiologist. These data include statistics regarding frequency of radiologic errors, factors that affect conspicuity of radiographic densities, the limitations of normal human psychovisual physiology, and evidence that the radiologist had conducted himself or herself in a careful and appropriate manner. In addition, a jury might determine that testimony from radiology experts retained by the plaintiff is not compelling because of hindsight bias. Indeed, perhaps the jurors themselves might conclude that they, too, are being adversely influenced by hindsight bias.
It is, of course, not known whether a jury can be persuaded to rule in favor of a defendant radiologist who is alleged to have missed a radiographic diagnosis because of the defense-supporting factors mentioned. What is known, however, is that the number of medical malpractice cases filed against radiologists alleging a missed diagnosis continues to increase, and thus there will be ample opportunity in the future to present to juries as a defense the concepts of hindsight bias, perceptual error rates, and human psychovisual phenomena.
Acknowledgments
I thank John W. Schedler for his assistance in the preparation of this
article.
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