Hindsight bias

Characteristics of Radiologists Serving as Medical Malpractice Expert Witnesses for Defense Versus Plaintiff

PURPOSE

Previous studies have reported higher qualification characteristics for anesthesiologists, neurosurgeons, orthopedic surgeons, and otolaryngologists serving as defense (versus plaintiff) medical malpractice expert witnesses. We assessed such characteristics for radiologist expert witnesses.

METHODS

Using the Westlaw legal research database, we identified radiologists serving as experts in all indexed medical malpractice cases between 2010 and 2019. Online databases were used to identify years of practice experience and scholarly bibliometrics. Using Medicare claims, individual radiologist practice types and mixes were ascertained. Radiologists testifying at least once each for defense and plaintiff were excluded from our defense-only versus plaintiff-only comparative analysis.

RESULTS

Initial Boolean searches yielded 1,042 potential cases; subsequent manual review identified 179 radiologists testifying in 231 lawsuits: 143 testified in one case (58 defense, 85 plaintiff) and 36 testified in multiple cases (10 defense-only, 14 plaintiff-only, 12 both). The 68 defense-only experts had fewer years of practice experience than the 99 plaintiff-only experts (28.3 versus 31.8 years, P = .02), but the two groups were otherwise similar in both practice type (44.6% versus 54.9% academic, P = .62) and mix (63.8% versus 65.8% practiced as subspecialists, P = .37) and as well as numbers of publications (60.5 versus 62.8, P = .86), citations (1,994.1 versus 2,309.2, P = .56), and h-indices (17.2 versus 16.8, P = .89).

CONCLUSIONS

In contrast to other specialists, radiologists serving as medical malpractice expert witnesses for defense and plaintiff display similar qualifications across various characteristics. Published practice parameter guidelines and experts' ability to blindly review archived original images might together explain this interspecialty discordance.

The Role of the Expert Witness in Radiology: Challenges and Strategies for Overcoming Them

Expert witnesses provide an important service in malpractice cases in the United States because they educate the jury on the standards of care relevant to a particular case. In cases in which the defendant physician is a radiologist, the decision often rests on whether a retrospectively detected abnormality should have been perceived and reported, an "error of omission." Errors of omission are usually termed "perceptual" in the literature and are the most common cause of malpractice suits in radiology. Allegations often hinge on whether these errors represent a breach of duty by the defendant radiologist and whether they resulted in an injury to the plaintiff or patient. In short, jurors are asked to decide if the radiologist performed below the "standard of care," generally defined as that which a minimally competent, reasonable, or ordinary physician in the same field would do under similar circumstances. The authors describe challenges associated with being an expert witness and provide guidance to radiologists on how to address cases involving alleged perceptual errors.

The Effect of Visual Hindsight Bias on Radiologist Perception

RATIONALE AND OBJECTIVES

To measure the effect of visual hindsight bias on radiologists' perception during chest radiograph pulmonary nodule detection.

MATERIALS AND METHODS

This was a prospective multi-observer study to assess the effect of hindsight bias on radiologists' perception. Sixteen radiologists were asked to interpret 15 postero-anterior chest images containing a solitary lung nodule each consisting of 25 incremental levels of blur. Participants were requested initially to detect the nodule by reducing the blur of the images (foresight). They were then asked to increase the blur until the identified nodule was undetectable (hindsight). Participants then repeated the experiment, after being informed of the potential effects of hindsight bias and asked to counteract these effects. Participants were divided into two groups (experienced and less experienced) and the nodules were given different conspicuity ratings to determine the effect of expertise and task difficulty. Eye tracking technology was also utilised to capture visual search.

RESULTS

Wilcoxon analysis demonstrated significant differences between foresight and hindsight values of the radiologists (p = 0.02). However, after being informed of hindsight bias, these differences were no longer significant (p = 0.97). Friedman analysis also determined overall significance in the hindsight ratios between nodule conspicuities for both phases (phase 1: p = 0.02; phase 2: p = 0.02). There was no significance difference between the experienced and less experienced groups.

CONCLUSION

This study demonstrated that radiologists exhibit hindsight bias but appeared to be able to compensate for this phenomenon once its effects were considered. Also, visual hindsight bias appears to be affected by task difficulty with a greater effect occurring with less conspicuous nodules.

Analysis of medical malpractice claims to improve quality of care: Cautionary remarks

Medical malpractice claims can be analysed to gain insights aimed at improving quality of care. However, using medical malpractice claims in medical research raises epistemological and methodological concerns related to certain features of the litigation process. Medical research should therefore approach medical malpractice claims with caution. Taking one recent study as a an example, this article insists on three areas of concern: (a) the quantity of legal materials available for analysis; (b) the content of the legal materials available for analysis; and (c) the ways in which the content of the legal materials should be analysed and the types of inferences that it can support. The article concludes with general recommendations for future medical research that would incorporate medical malpractice claims. These recommendations centre around recognizing the qualitative dimension of legal reasoning.

Threshold of metabolic acidosis associated with newborn cerebral palsy: medical legal implications

Obstetricians and gynecologists belong to 1 of the medical specialties with the highest rate of litigation claims. Among birth injury cases, those cases with cerebral palsy outcomes account for litigation settlements or judgments often in the millions of dollars. In cases of potential perinatal asphyxia, a threshold level of metabolic acidosis (base deficit ≥12 mmol/L) is necessary to attribute neonatal encephalopathy to an intrapartum hypoxic event. With increasing duration or severity of a hypoxic stress resulting in metabolic acidosis, newborn infant umbilical artery base deficit increases. It may be alleged that, as base deficit levels increase beyond 12 mmol/L, there is an increased likelihood and severity of cerebral palsy. As a corollary, it may be claimed that an earlier delivery (by minutes) would reduce the base deficit and prevent or reduce the severity of cerebral palsy. This issue is of relevance to obstetricians as defendants, because retrospective "expert" analysis of cases may suggest that optimal management decisions would have resulted in an earlier delivery. In addressing the association of metabolic acidosis and cerebral palsy, base deficit should be measured as the extracellular component (base deficit_{extracellular fluid}) rather than the commonly used base deficit_blood. Studies suggest that, beyond the base deficit threshold of 12 mmol/L, the incidence and severity of cerebral palsy does not significantly increase (until ≥20 mmol/L), although the risk of neonatal death rises markedly. Thus, among most infants with hypoxia-associated neonatal encephalopathy, the occurrence of cerebral palsy is unlikely to be impacted by delivery time variation of few minutes, and this argument should not serve as the basis for medical legal claims.

Systematic error and cognitive bias in obstetric ultrasound

Linked Comment: Ultrasound Obstet Gynecol 2019; 53: 454-464.

Redefining the Practice of Peer Review Through Intelligent Automation Part 1: Creation of a Standardized Methodology and Referenceable Database

Conventional peer review practice is compromised by a number of well-documented biases, which in turn limit standard of care analysis, which is fundamental to determination of medical malpractice. In addition to these intrinsic biases, other existing deficiencies exist in current peer review including the lack of standardization, objectivity, retrospective practice, and automation. An alternative model to address these deficiencies would be one which is completely blinded to the peer reviewer, requires independent reporting from both parties, utilizes automated data mining techniques for neutral and objective report analysis, and provides data reconciliation for resolution of finding-specific report differences. If properly implemented, this peer review model could result in creation of a standardized referenceable peer review database which could further assist in customizable education, technology refinement, and implementation of real-time context and user-specific decision support.

Error and discrepancy in radiology: inevitable or avoidable?

Errors and discrepancies in radiology practice are uncomfortably common, with an estimated day-to-day rate of 3-5% of studies reported, and much higher rates reported in many targeted studies. Nonetheless, the meaning of the terms "error" and "discrepancy" and the relationship to medical negligence are frequently misunderstood. This review outlines the incidence of such events, the ways they can be categorized to aid understanding, and potential contributing factors, both human- and system-based. Possible strategies to minimise error are considered, along with the means of dealing with perceived underperformance when it is identified. The inevitability of imperfection is explained, while the importance of striving to minimise such imperfection is emphasised.

TEACHING POINTS

• Discrepancies between radiology reports and subsequent patient outcomes are not inevitably errors. • Radiologist reporting performance cannot be perfect, and some errors are inevitable. • Error or discrepancy in radiology reporting does not equate negligence. • Radiologist errors occur for many reasons, both human- and system-derived. • Strategies exist to minimise error causes and to learn from errors made.

Minimising the impact of errors in the interpretation of CT images for surveillance and evaluation of therapy in cancer

Radiological error is inevitable and usually multifactorial. Error can be secondary to radiologist-specific causes, including cognitive and perceptive errors or ambiguity of report, or system-related causes, including inadequate, misleading, or incorrect clinical information, poor imaging technique, excessive workload, and poor working conditions. In this paper, we discuss a systematic approach to reduce errors in oncological radiology reporting, thus reducing risk to the patient. Rather than attempt to discuss all types of error, we concentrate on the most important and commonly occurring errors that we have encountered over 20 years of practice, based on weekly discrepancy reviews of our practice and independent reviews of clinical and research imaging from other institutions. This review focuses on computed tomography (CT) reporting for staging, surveillance, and response assessment of cancer patients, but the messages apply to all imaging methods.

Outcomes Knowledge May Bias Radiological Decision-making

RATIONALE AND OBJECTIVES

This research investigates whether an expectation of abnormality and prior knowledge might potentially influence the decision-making of radiologists, and discusses the implications for radiological expert witness testimony.

MATERIALS AND METHODS

This study was a web-based perception experiment. A total of 12 board-certified radiologists were asked to interpret 40 adult chest images (20 abnormal) twice and decide if pulmonary lesions were present. Before the first viewing, a general clinical history was given for all images: cough for 3+ weeks. This was called the "defendants read." Two weeks later, the radiologists were asked to view the same dataset (unaware that the dataset was unchanged). For this reading, the radiologists were given the following information for all images: "These images were reported normal but all of these patients have a lung tumour diagnosed on a subsequent radiograph 6 months later." They were also given the lobar location of the newly diagnosed tumor. This was called the "expert witness read."

RESULTS

There was a significant difference in location-based sensitivity (W = -45, P = 0.02) between the two conditions with nodule detection increasing under the second condition. Specificity increased outside the lobe of interest (W = 727, P = < 0.0001) and decreased within the lobe of interest (W = -237, P = 0.03) significantly in the "expert witness" read. Case-based sensitivity and case-based specificity were unaffected.

CONCLUSIONS

This study showed evidence that increased clinical information affects the performance of radiologists. This effect may bias expert witnesses in radiological malpractice litigation.

Hindsight Bias

Hindsight bias occurs when people feel that they "knew it all along," that is, when they believe that an event is more predictable after it becomes known than it was before it became known. Hindsight bias embodies any combination of three aspects: memory distortion, beliefs about events' objective likelihoods, or subjective beliefs about one's own prediction abilities. Hindsight bias stems from (a) cognitive inputs (people selectively recall information consistent with what they now know to be true and engage in sensemaking to impose meaning on their own knowledge), (b) metacognitive inputs (the ease with which a past outcome is understood may be misattributed to its assumed prior likelihood), and (c) motivational inputs (people have a need to see the world as orderly and predictable and to avoid being blamed for problems). Consequences of hindsight bias include myopic attention to a single causal understanding of the past (to the neglect of other reasonable explanations) as well as general overconfidence in the certainty of one's judgments. New technologies for visualizing and understanding data sets may have the unintended consequence of heightening hindsight bias, but an intervention that encourages people to consider alternative causal explanations for a given outcome can reduce hindsight bias.

Expert witness blinding strategies to mitigate bias in radiology malpractice cases: a comprehensive review of the literature

Like all physicians, radiologists in the United States are subject to frequent and costly medical malpractice claims. Legal scholars and physicians concur that the US civil justice system is neither precise nor accurate in determining whether malpractice has truly occurred in cases in which claims are made. Sometimes, this inaccuracy is driven by biases inherent in medical expert-witness opinions. For example, expert-witness testimony involving "missed" radiology findings can be negatively affected by several cognitive biases, such as contextual bias, hindsight bias, and outcome bias. Biases inherent in the US legal system, such as selection bias, compensation bias, and affiliation bias, also play important roles. Fortunately, many of these biases can be significantly mitigated or eliminated through the use of appropriate blinding techniques. This paper reviews the major works on expert-witness blinding in the legal scholarship and the radiology professional literature. Its purpose is to acquaint the reader with the evidence that unblinded expert-witness testimony is tainted by multiple sources of bias and to examine proposed strategies for addressing these biases through blinding.

Biases in radiologic reasoning

OBJECTIVE

The purpose of this article is to outline common biases in medical reasoning that contribute to avoidable errors in diagnostic and therapeutic decision making.

CONCLUSION

By recognizing and understanding common biases in medical reasoning, we can more effectively counteract them.

The legal implications of error in radiology

Evaluation of the legal implications of error in radiology and therefore the assessment of criminal and civil liability in the practice of the profession requires an analysis of how the public perception of the right to health has radically changed. This change has initiated a defensive approach to medicine and radiology that tends to be oriented towards precautionary measures, with a proliferation of often unnecessary imaging studies. In radiology, errors of omission or commission are frequent. A critical appraisal of the different types of error in radiology will help practitioners undertake the essential corrective measures. Through analysis of several cases derived from legal or insurance proceedings brought against radiologists, the most common forms of error are described, and their implications for criminal and civil liability are illustrated, although it is emphasised that the existence of an error does not always translate into the presence of malpractice.

A true screening environment for review of interval breast cancers: pilot study to reduce bias

PURPOSE

To retrospectively assess the feasibility of an uninformed review process to evaluate interval breast cancers and to compare the number of false-negative cancers detected at uninformed review with the number detected at standard informed review.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study, and informed consent was waived. Mammograms showing interval cancer were included in the daily work of radiologists in a high-volume screening center. Each of three experienced radiologists read studies in the normal screening environment, without knowledge that identifiers had been changed to conceal the fact that studies were not current (ie, uninformed review). Results were compared with the standard review procedure, in which mammograms showing interval cancers were mixed with normal mammograms and read in a panel of 17-20 interval cancers per 80 normal studies by radiologists who were aware that they were participating in a review process (ie, informed review).

RESULTS

Of 21 interval cancers, six (29%) were interpreted as positive more often by the informed radiologists than by the uninformed radiologists. For 14 (67%) cancers, there was no difference in detection rate between the two groups, and one cancer (5%) was seen by one of the uninformed radiologists but by none of the informed radiologists. The screening environment review process was found to be feasible at the low volumes tested.

CONCLUSION

The number of false-negative cancers was higher in the informed review than in the uninformed review. This result suggests that bias exists with the informed review process.

Medical malpractice and anesthesiology: literature review and role of the expert witness

PURPOSE

To provide a narrative review of the physician experience of medical malpractice litigation applied to an anesthesiology case with particular emphasis on the role played by medical expert witnesses.

SOURCES

Literature searches were conducted of English-language medical publications published between 1996 - 2006 using both Medline and Pubmed databases. Key words included: "medical malpractice"; "medical malpractice litigation"; "medical expert witness"; "expert witness liability", "expert witness bias"; "hindsight bias"; and "outcome bias".

PRINCIPAL FINDINGS

Patient injury resulting from medical care is common but most injured patients do not sue. Implicit review of medical files is biased to an important degree by the occurrence of severe injury; care is more often deemed substandard when the resulting injury is severe. Expert analysis of medical mal-occurrences is influenced by both hindsight and outcome bias. Compensation for those who do sue is influenced by the severity of injury and the degree of disability. The activity of experts is not commonly subject to review by peers, professional groups or licensing authorities.

CONCLUSIONS

The legal process for resolving patient claims against physicians is well delineated and transparent; its operational features are complex and prejudiced by severe outcomes. Bias is pervasive in the analysis of medical occurrences and may result in findings against caregivers which are unfair.

Identification of systems failures in successful paediatric cardiac surgery

Patient safety will benefit from an approach to human error that examines systemic causes, rather than blames individuals. This study describes a direct observation methodology, based on a threat and error model, prospectively to identify types and sources of systems failures in paediatric cardiac surgery. Of substantive interest were the range, frequency and types of failures that could be identified and whether minor failures could accumulate to form more serious events, as has been the case in other industries. Check lists, notes and video recordings were employed to observe 24 successful operations. A total of 366 failures were recorded. Coordination and communication problems, equipment problems, a relaxed safety culture, patient-related problems and perfusion-related problems were most frequent, with a smaller number of skill, knowledge and decision-making failures. Longer and more risky operations were likely to generate a greater number of minor failures than shorter and lower risk operations, and in seven higher-risk cases frequently occurring minor failures accumulated to threaten the safety of the patient. Non-technical errors were more prevalent than technical errors and task threats were the most prevalent systemic source of error. Adverse events in surgery are likely to be associated with a number of recurring and prospectively identifiable errors. These may be co-incident and cumulative human errors predisposed by threats embedded in the system, rather than due to individual incompetence or negligence. Prospectively identifying and reducing these recurrent failures would lead to improved surgical standards and enhanced patient safety.

The "saw-it-all-along" effect: demonstrations of visual hindsight bias

The authors address whether a hindsight bias exists for visual perception tasks. In 3 experiments, participants identified degraded celebrity faces as they resolved to full clarity (Phase 1). Following Phase 1, participants either recalled the level of blur present at the time of Phase 1 identification or predicted the level of blur at which a peer would make an accurate identification. In all experiments, participants overestimated identification performance of naive observers. Visual hindsight bias was greater for more familiar faces--those shown in both phases of the experiment--and was not reduced following instructions to participants to avoid the bias. The authors propose a fluency-misattribution theory to account for the bias and discuss implications for medical malpractice litigation and eyewitness testimony.

Error in radiology

Literature review indicates high levels of error within radiology. The aetiology of radiological error is multi-factorial. While individuals have a duty to progressively improve their performance, the experience of safety cultures in other high-risk human activities has shown that a system approach of root cause analysis is the method required to reduce error significantly.