Knowledge or reasoning gap: how to tell

You miss a case and the first reaction is to reread the disease in the book. Sometimes that is it: you needed to know it. Other times you knew everything about the disease and it still did not make it onto your list of hypotheses. These are two different gaps, and each one calls for a type of study.

NEXO is a daily medical diagnosis game: one clinical case a day, six progressive clues, and ICD-10 proximity feedback across five levels.

This guide summarizes what the research says about the origin of diagnostic error, why knowledge and reasoning go so closely together and how to find out which of the two gaps is weighing more on your study.

Main points

• A knowledge gap is not having the information; a reasoning gap is having the information and not using it at the right moment.
• The most recent studies weigh knowledge more heavily than was thought: checklists to "think better" helped little.
• Expert reasoning is, to a large extent, knowledge well organized around cases.
• The practical way to separate the two gaps is to look at the error: was the right disease on your list or not?
• Training with varied cases helps on both sides, because it forces you to seek the knowledge starting from the clinical picture.

What each gap is

Knowledge gap

It is the lack of information: you did not know the disease, did not remember the typical finding or did not know what a test indicates. The fix is to study the content, preferably by testing your memory, and not just rereading.

Reasoning gap

It is having the information and not reaching it. The disease exists in your memory, but the clinical picture did not bring it to the surface, or it made the list and was discarded too early. The fix involves practicing with cases: summarizing the problem, generating hypotheses, comparing alternatives and reviewing the list with every new piece of data. The guide to clinical reasoning in the clinical cycle details these steps.

What the studies say about the cause of the error

Reasoning errors appear frequently

In a review of records of patients with dyspnea in five Dutch hospitals, failures in diagnostic reasoning appeared in 66% of the records analyzed, and the records with more failures had more diagnostic error and more harm to the patient (Zwaan et al., 2012). The most common cause was classified as a mistake: the doctor followed a wrong path without realizing it was wrong (Zwaan et al., 2012). This finding shows that the process matters, but it does not say whether the failure came from lack of knowledge or from poor use of knowledge.

Checklists to "think better" helped little

A trial with residents and cardiologists in training compared, in reading electrocardiograms, a checklist against cognitive biases, a content checklist and no checklist (Sibbald et al., 2019). Neither checklist improved overall performance compared with the control, not even on the tracings designed to induce bias; the authors note that they might help beginners (Sibbald et al., 2019).

A British consensus statement on the clinical reasoning curriculum reached a similar conclusion when reviewing the literature: teaching general thought processes showed little effectiveness, while strategies aimed at building knowledge and understanding brought improvement (Cooper et al., 2021).

The topic still has little space in the curriculum

In a survey with internal medicine clerkship directors in the United States, 57% of schools had no sessions dedicated to clinical reasoning, and lack of time in the curriculum was the most cited barrier (Rencic et al., 2017). According to the same directors, most students arrived at the clerkship with poor or fair knowledge of the concepts of clinical reasoning (Rencic et al., 2017).

Why the two gaps get mixed up

The expert's knowledge is organized

In a study with second- and fourth-year students and family physicians, the physicians gave more accurate diagnoses and were faster and more accurate at judging what related to each case (Rikers et al., 2004). Their best performance was on "encapsulated" concepts, those that sum up several findings in a clinical concept, which led the authors to conclude that this compact knowledge becomes the basis of case representation as experience grows (Rikers et al., 2004).

In practice, this means that much of what we call the specialist's "reasoning" is well-tied knowledge. When a student "reasons poorly", often the knowledge is there, but in loose pieces.

Connecting theory and case takes time

In a ten-week course with patient contact, third-year students improved diagnostic accuracy, became faster and began to explain pathophysiology with more correct concepts and fewer wrong links (Diemers et al., 2015). The gain was smaller on transfer cases, different from those seen in the course, and the authors recommend many varied contacts with the same underlying mechanism (Diemers et al., 2015). The text about connecting mechanism and symptom shows how to make that bridge while studying.

Intuition and analysis add up

In an experiment with electrocardiograms, beginners who received the instruction to combine analysis of the findings with the impression of similarity got more right (56% and 53%) than those who used only analysis (42%) or only first impression (41%) (Ark et al., 2006). The impression of similarity depends on cases stored in memory, that is, on knowledge; analysis depends on knowing which findings to look for. The two gaps, again, appear together.

How to separate the two gaps in your study

The most useful question after a mistake is simple: did the right disease enter your list of hypotheses?

What happened	Most likely gap	What to study
You did not know the disease or the key finding	Knowledge	The content, with questions and spaced review
You knew the disease, but it did not enter the list	Reasoning (hypothesis generation)	Varied cases with the same main complaint
The disease entered the list and left early	Reasoning (early closure)	Review the list with every new piece of data; compare the alternatives
You got it right, but you cannot say why	Both	Explain the case out loud and check it in the explanation

Two editorial examples:

• A student misses a case of abdominal pain and fever because they did not remember that a disease can start with periumbilical pain that later migrates. It is a lack of knowledge.
• Another student knew that progression well, but fixed the first hypothesis right at the start and did not return to it when the pain changed place. It is a reasoning problem, even with complete knowledge.

The error notebook offers a way to record this type of mistake and to review in a cycle.

What each gap asks of training

For the knowledge gap

Study the content by testing memory, not by rereading. The guide on testing yourself to remember explains why. Prefer learning the disease from the clinical picture: symptoms, progression and findings that set it apart from its neighbors.

For the reasoning gap

Practice with short, varied cases, in which information arrives little by little. With each new piece of data, rewrite the list of hypotheses. Compare two similar diseases side by side. The guide on differential diagnosis with clues offers exercises in this format.

For both at the same time

Return to the content after each missed case. The case gives the context and the content gives the explanation; together, they organize knowledge around clinical pictures, which is how specialists store it (Rikers et al., 2004).

How NEXO shows where reasoning changed

In NEXO, the case arrives in up to six clues, one at a time, and each guess receives proximity feedback in ICD-10 at five levels: Exact ICD, Same category, Same group, Same chapter or Different chapter. This format helps answer the question in the table above. A guess in the right chapter but the wrong group suggests that you were close and a piece of data or a detail of the disease was missing. A guess in another chapter suggests that the hypothesis started from a different place.

After the case, the clinical explanation in the result is the way back to the content. On the home screen, the distribution of correct answers per clue shows how many clues it usually takes for you to close the diagnosis, and, just below, the specialties where you get the most right answers appear. The Modes screen gives access to the Archive, with previous daily cases, to return to an area where you made a mistake. How each mode is unlocked is on the NEXO Economy page.

If you research clinical reasoning and want to study knowledge and reasoning gaps with NEXO, meet NEXO Researcher. To bring NEXO to your medical school, student league or residency, there is NEXO Closer. Doctors who review cases in their specialty take part through NEXO Curator, and those who create health content on social media can take part through NEXO Creators.

Frequently asked questions

What is the difference between a knowledge gap and a reasoning gap?

In a knowledge gap, the information is missing. In a reasoning gap, the information exists, but it is not used at the right time: the disease does not enter the list of hypotheses or leaves it too early.

Does diagnostic error come more from lack of knowledge or from bias?

The question is still under debate. A trial with checklists against biases and content checklists found little effect of either on reading electrocardiograms (Sibbald et al., 2019), and a British consensus found more gain in strategies that build knowledge than in teaching general thought processes (Cooper et al., 2021).

How do I know which gap is mine?

After each error, ask whether the right disease entered your list. If you did not know it, the gap is in knowledge. If you knew it and it did not appear, or it appeared and left early, the gap is in reasoning.

Can clinical reasoning be trained?

It is trained with practice on varied cases and with feedback on each answer. Students who had contact with patients in a ten-week course improved their accuracy and the organization of their knowledge (Diemers et al., 2015).

Does NEXO help find my gap?

NEXO shows the proximity in ICD-10 of each guess and on which clue you got it right, and brings the clinical explanation of the case in the result. This record helps answer whether the disease was close to your hypothesis. To get to know the game, read what NEXO is.

Checklist to find your gap

1. After each error, note whether the right disease entered your list.
2. Unknown disease: study the content by testing your memory.
3. Known disease that did not appear: train cases with the same main complaint.
4. Disease that left early: review the list with every new piece of data.
5. Right answer without explanation: explain the case out loud and check.
6. Learn the disease from the clinical picture, and not only from the list of criteria.
7. Compare neighboring diseases side by side.
8. Go back to the content after each case you get wrong.

Want to train with a short case a day? Play the case of the day on NEXO.

References

1. Zwaan L, Thijs A, Wagner C, van der Wal G, Timmermans DR. Relating faults in diagnostic reasoning with diagnostic errors and patient harm. Acad Med. 2012. https://pubmed.ncbi.nlm.nih.gov/22189886/
2. Sibbald M, Sherbino J, Ilgen JS, et al. Debiasing versus knowledge retrieval checklists to reduce diagnostic error in ECG interpretation. Adv Health Sci Educ Theory Pract. 2019. https://pubmed.ncbi.nlm.nih.gov/30694452/
3. Cooper N, Bartlett M, Gay S, et al. Consensus statement on the content of clinical reasoning curricula in undergraduate medical education. Med Teach. 2021. https://pubmed.ncbi.nlm.nih.gov/33205693/
4. Rencic J, Trowbridge RL Jr, Fagan M, Szauter K, Durning S. Clinical Reasoning Education at US Medical Schools: Results from a National Survey of Internal Medicine Clerkship Directors. J Gen Intern Med. 2017. https://pubmed.ncbi.nlm.nih.gov/28840454/
5. Rikers RM, Loyens SM, Schmidt HG. The role of encapsulated knowledge in clinical case representations of medical students and family doctors. Med Educ. 2004. https://pubmed.ncbi.nlm.nih.gov/15461648/
6. Diemers AD, van de Wiel MW, Scherpbier AJ, Baarveld F, Dolmans DH. Diagnostic reasoning and underlying knowledge of students with preclinical patient contacts in PBL. Med Educ. 2015. https://pubmed.ncbi.nlm.nih.gov/26611188/
7. Ark TK, Brooks LR, Eva KW. Giving learners the best of both worlds: do clinical teachers need to guard against teaching pattern recognition to novices? Acad Med. 2006. https://pubmed.ncbi.nlm.nih.gov/16565197/