Reframing diagnostic error: maybe it's content, and not process, that leads to error.

Dr. Ritter identifies a key task required of emergency physicians (EPs), the ability to diagnose life-threatening conditions in undifferentiated patients within the chaotic environment of the emergency department. Studies demonstrate that EPs simultaneously care for greater than five patients (range, 2 to 16) at a time, while being interrupted 10 to 20 times per hour. Thus, diagnostic reasoning (and by implication diagnostic error) has become an increasingly important topic in medicine in general and in emergency medicine (EM) in particular. Research in medical education has focused on the process of clinical reasoning in an attempt to develop strategies to prevent diagnostic error. Theories of clinical reasoning include dual processing theory, which involves an unconscious, heuristic-based System 1 and a conscious, analytical System 2; cognitive continuum theory, which argues for a continuum between pure intuition and pure analysis with the clinical problem determining the degree of “quasirationality” required; and fuzzy trace theory, which suggests there are two types of memory that inform decision-making, verbatim (literal facts) and gist (representative or relational facts). While a full description of the merits of each of these theories is beyond the scope of this commentary, a dominant argument in the literature is that intuitive or unconscious reasoning (System 1) is the main source of diagnostic error, as a consequence of the cognitive biases presumed inherent in this nonanalytical approach. Therefore, it is argued that diagnostic errors can be reduced by understanding and limiting the influence of cognitive biases on the reasoning process. These strategies are collectively referred to as “cognitive forcing strategies. ” However, our research suggests that cognitive forcing strategies, which provide metacognitive approaches to self-monitoring the diagnostic process, are ineffective. While these studies have been criticized for using medical students, who may lack sufficient clinical experience to use automatic, System 1 reasoning and thus do not require inoculation against cognitive biases, these are the only studies to our knowledge that have experimentally evaluated the educational benefit of metacognition to prevent diagnostic error. Other studies from our research group challenge more broadly the assumption that automatic, unconscious, heuristic, System 1 reasoning is the source of diagnostic error (with System 2 failing to correct it). Our research suggests that rapid diagnosis (a surrogate for unconscious, nonanalytical System 1 reasoning) is associated with fewer errors. Conversely, encouraging residents to slow down and pay attention (allowing more time for deliberate, analytical System 2 reasoning) did not reduce error; it simply made residents slower. These findings have been replicated and extended in a multicenter, randomized trial that specifically incorporated EM trainees and physicians and, showed, not surprisingly, that EPs were both faster and more accurate than trainees. Conversely, specific strategies to encourage conscious, reflective, System 2 reasoning had no effect on accuracy, although the strategies increased diagnostic processing time by a factor of 3. There is some evidence that deliberate, intensive reflection, directed at a critical examination of the relation between signs, symptoms, and diagnoses (and not at identification of cognitive biases), can lead to reduction in errors, but such a strategy, while it may have educational benefits, is not feasible in the clinical practice of EM. With regard to the effect of interruptions, a recent study, which incorporated distractions to mimic authentic clinical practice, showed that diagnostic accuracy correlates with clinical experience and (again) is not affected by instructions to slow down and be consciously systematic (i.e., System 2 reasoning) in the diagnostic process. Perhaps surprisingly, the effect of multiple distractions was to add a few seconds to the diagnostic processing time of each case, but again there was no negative effect on accuracy. While these studies have been criticized for the use of written cases, which lack face validity to mimic actual diagnostic processes in clinical practice, other studies of medical students have demonstrated that performance on written cases is equivalent to performance on both simulated cases and real patients. In any case, with the exception of a few retrospective studies of causes of error, the entire empirical basis for the purported effect of cognitive bias on cognitive reasoning is derived from written cases, both within and outside of medicine (and entirely from first-year undergraduate psychology students in the latter case). The authors have no relevant financial information or potential conflicts of interest to disclose. A related article appears on page 940.