NURS 680B Week 8 Discussion diagnostic reasoning process

The ability to transform medical data into an actionable diagnosis is paramount to the functioning and identity of every physician. This first fundamental step in patient care is complex and prone to errors yet is infrequently considered to be a focus of potential improvement.

Given the costs and dangers of an incorrect diagnosis, improving diagnostic accuracy has been called the next frontier for patient safety. An incorrect working diagnosis can lead to treatment of a nonexistent condition as well as a delay in appropriate therapy for an existing condition. Shojania et al found that 5% of autopsies demonstrate diagnostic errors leading to lethal complications that would have been averted by treatment if the correct disease had been diagnosed. Malpractice lawsuits about diagnostic errors are more common than lawsuits about medication errors and result in larger payouts.

Knowledge and experience are the cornerstones of strong diagnostic skills, but the ongoing improvement of a clinician’s diagnostic skills requires a basic understanding of the cognitive process that underlies diagnosis and a commitment to lifelong learning and expertise principles. Decades of study on physicians’ judgment and reasoning, have yielded practical insights into how to optimize the diagnostic thought process.

In the first part of this article, we present a summary of the cognitive psychology of diagnostic reasoning. In the second part, we suggest changes that both individual clinicians and health care systems can adopt to improve diagnostic accuracy and improve patient care and safety.

The Science of Diagnostic Reasoning

Many clinical encounters require a modest number of data points for diagnosis. For example, a brief medical history from a healthy woman, age 30 years, with dysuria is largely sufficient to diagnose a urinary tract infection. Extensive listing of other diagnostic possibilities is impractical and frequently superfluous. This type of reasoning employs the intuitive system in our brain, which conducts a rapid mental comparison of the current case with an abstract prototypical picture (“illness script”) of common causes of dysuria such as a urinary tract infection. The brain performs this comparison on the basis of past experience and knowledge through a process that is largely inaccessible to conscious control or manipulation. This seemingly instantaneous process was celebrated by Malcolm Gladwell for its utility and efficacy in his best seller Blink: The Power of Thinking Without Thinking.

Common, straightforward cases dominate daily practice, but clinicians are also faced with patient encounters that do not fit previously recognized patterns. Take, for example, the case of a man, age 42 years, with back pain, a serum calcium level of 6.9 mg/dL, and a hemoglobin level of 6.3 g/dL. To make sense of such a scenario, a clinician employs the more deliberate and time-consuming method of analytic reasoning. The physician must comb through memory and knowledge stores and frequently use external information sources to derive a clinical solution. The aforementioned case does not immediately trigger a unifying diagnosis and explanation, but with extended thinking, consideration of pathophysiology, consultation with colleagues, and use of online resources, the physician might deduce that this patient’s anemia is due to malabsorption leading to vitamin D deficiency, with the ensuing osteomalacia causing bone pain. Further analysis may allow her to arrive at the underlying diagnosis of celiac disease.

Studies using functional magnetic resonance imaging suggest that intuitive and analytic reasoning correspond to the activation of separate brain structures—the ventral medial prefrontal cortex and right inferior prefrontal cortex, respectively. However, in human reasoning and decision making, the two systems are not used in isolation. Rather, they exist on a cognitive continuum: Ideas generated by intuition are subject to analytic scrutiny, and conclusions that are reached through formal analysis may be overridden by intuition (eg, “I will admit this patient with chest pain for exclusion of MI [myocardial infarction] despite the low TIMI [Thrombolysis in Myocardial Ischemia] risk score”).