Inadequate clinical reasoning can lead to errors in daily clinical practice  and impact patient safety , . In an earlier study, our group found that about 50% of diagnoses made by intermediate and advanced medical students working with virtual patients were incorrect . Diagnostic errors made by medical students were divided into eight different categories : errors caused by a lack of diagnostic skills, lack of knowledge, premature closure, misidentification, faulty context generation, faulty triggering, over- and underestimating, and no hypothesis. The first three were the most common errors.
To improve the clinical reasoning process of students and decrease the rate of misdiagnoses, different instructional approaches have been tested. Instructions that help students approach clinical cases are defined as scaffolding , . Scaffolding during the diagnostic process seems to improve clinical reasoning, although the results are contradictory.
One type of scaffold is a representation prompt. Representations (or case summaries) can help students and experts to solve clinical cases , , , and practicing representations while diagnosing cases correlates with a correct solution . In a previous study, we used representation prompts to foster clinical reasoning by medical students , . Students were prompted to imagine a ward round setting and write down how they would present their patient to a colleague. Representation improved students’ diagnostic efficiency but did not improve accuracy.
Structured reflection is another type of scaffold. One such approach is to ask participants to think about the three most-likely diagnoses in a case and to write down all the information that supports and refuses their diagnoses. They are also asked to think about information that is missing in the case but would support their differential diagnoses . Structured reflection can foster the diagnostic accuracy of medical students (including at a 1-week delayed assessment)  but these results are not seen in all studies . It is unknown how structured reflection might affect the time spent on a case and if the causes of diagnostic errors are influenced by structured reflection.
While there have been many studies on structured reflection and feedback (on diagnosis) and a few studies on representation, no data are available about the effects of representation scaffolds in combination with feedback. Also, the long-term effects of representation scaffolds have not been tested. Finally, there is no direct comparison of the effects of representation and reflection. Another important aspect in daily clinical practice is diagnostic efficiency. Due to limited time and resources in daily clinical practice, it is crucial to diagnose efficiently. Diagnostic efficiency can be defined as the number of (correctly) solved cases divided by the time needed for diagnosis . Representation scaffolds can improve diagnostic efficiency in certain settings but it is unclear how feedback and structured reflection influence it.
Based on the literature and previous studies, we hypothesize the following:
Scaffolding with feedback is superior to scaffolding without feedback in improving diagnostic accuracy.
Representation scaffolding in a learning phase should lead to a more efficient diagnostic process in an immediate and delayed assessment than a reflection scaffold.
Reflection scaffolding is superior to representation scaffolding for improving diagnostic accuracy. The effects of structured reflection are still measurable with 1-week delay.
Both scaffolding methods (with or without feedback) are superior to a control group regarding diagnostic accuracy, efficiency, and rate of premature closure.
We chose a 2×2 design (representation or reflection scaffold with or without feedback) with a control group (no scaffold and no feedback) in a prospective, randomized, double-blinded setting to answer these questions.
Materials and methods
One hundred and fifty fourth and fifth year medical students from different medical schools in Germany who had successfully completed their courses in internal medicine participated in this study in June 2017. Participants received €30 for participating. Informed consent was obtained from all individuals included in this study. The study was approved by the Ethical Committee of the Medical Faculty of LMU Munich (No. 75-16).
Participants were randomly assigned to one of five groups (each n=30): a representation scaffold group (R0), a representation scaffold group with feedback (RF), a structured reflection group (S0), a structured reflection group with feedback (SF), and a control group (00). All participants analyzed five learning cases except the control group which immediately started working on the assessment cases. After the learning phase, the four intervention groups completed assessment 1 (five cases) and after 1 week, assessment 2 (five cases). The dependent variables were: accuracy (binary variable of correct or incorrect diagnosis), time on task (tracked by the electronic learning platform CASUS) , and diagnostic efficiency (correct diagnoses divided by time spent on task).
The nature of diagnostic errors was assessed by coding students’ written explanations and by tracking and analyzing the diagnostic steps as published previously . One investigator (KB) coded all the explanations. A second rater (LB) coded 15% of the explanations. The interrater coefficient analyzed with Cohen’s kappa was k=0.88. Both raters were blind to the group assignment. Both were familiar with the cases and with the coding scheme from the earlier study . First, a prototypical error for all eight categories was defined. The raters read the explanations and any errors were assigned to one of eight categories. The categories are defined in the following:
Figure 1 shows the course of the study. First, students were randomly assigned to one of the five groups. After an introduction video (which explained how to proceed through the cases and how the diagnostic tests can be selected), the students completed a questionnaire regarding socio-demographic characteristics. They also completed a pre-test on knowledge about dyspnea (consisting of 15 single-choice questions). They then worked within the electronic case simulation platform CASUS  on 15 clinical cases. All cases were structured identically. They started with a history including the chief complaint, history of present illness, medical history, and medication and drug use. This was followed by a full and standardized physical examination. Subsequently, participants could freely select among 10 diagnostic tests from a patient record in each case. The case history was compatible with at least three diagnoses. The contents of each patient record supported one diagnosis but the records also purposely included incidental and distracting findings such as slightly elevated laboratory parameters. The patient record information was well-matched to the pre-existing conditions and comorbidities of the patients [e.g. poor lung function in a patient with chronic obstructive pulmonary disease (COPD) as pre-existing illness]. The time spent analyzing information was not restricted. Finally, participants were free to decide when to close the case by naming and explaining their final diagnosis. The cases were developed by the study authors LB and KB based on anonymized material from real cases and were reviewed by four physicians. Diagnostic accuracy was binary coded (correct or incorrect) according to an expert solution of the case that was determined in advance. In a pilot phase, 10 students tested the feasibility of the study procedure and assessed the difficulty of the cases.
The cases in the learning phase pertained to dyspnea (see Figure 2). In assessment 1, two of the cases carried the identical diagnosis as in the learning phase. Another two of the cases shared possible differential diagnosis with the cases in the learning phase (myocarditis→heart failure, asthma→hyperventilation). The final case had abdominal pain as the primary symptom. In assessment 2, two cases had the same diagnosis as in the learning phase, two cases shared differential diagnoses, and one case had different content.
In the representation scaffold (R) group, the CASUS system interrupted case processing after the medical history, physical exam, and initial test results with the following case representation prompt: “Please sum up the case in 1–2 sentences as you would present it to your attending expert.”  In the structured reflection (S) group, the case processing was also interrupted at the same stage. Students had to write down their leading diagnosis and their differential diagnoses and had to explain which information supported their diagnosis and which information was contrary to it .
The feedback groups received a standardized feedback after giving their diagnosis in each case. The feedback was identically structured for all five cases: about 100 words long, explaining the important symptoms of the history and the key findings of the physical examination in addition to an explanation about the important diagnostic tests and important differential diagnoses (see Appendix). The no-feedback groups did not receive feedback or the correct solutions of the cases.
In an a priori power analysis for chi-squared (χ2) tests with df=4, we calculated that overall at least 100 participants should be tested in order to find a difference between the groups, assuming a small to medium effect (power: 1−β=0.80, Type I error: α=0.05, Cohen’s d=0.4). Gaussian distribution was tested by the Kolmogorov-Smirnov test. Due to a lack of normal distribution, differences between groups were tested by the Kruskal-Wallis test. p-Values were adjusted with the Bonferroni method, and p-values of ≤0.006 were considered to indicate statistical significance.
Characterization of the participants and learning phase
One hundred and forty-eight of 150 participants (108 women) processed all cases and were included in the data analysis. Table 1 shows the characteristics of the study population. There were no statistically significant differences between the five groups’ demographic variables. Prior knowledge with respect to dyspnea did not differ between the groups [χ2 (4)=4.81, p=0.31].
The learning time (see Table 2) was not different between the groups [χ2 (3)=8.62, p=0.04]: the representation groups needed mean=66.1 [standard deviation (SD)=20.9] min (without feedback) and mean=65.9 (SD=27.1) min (with feedback) to solve the five cases, whereas the reflection group needed mean=78.5 (SD=24.2) min (without feedback) and mean=62.3 (SD=24.9) min (with feedback). The participants solved between 2.7 and 3.1 of the five learning cases correctly; there was no significant difference between the groups [χ2 (3)=1.59, p=0.66]. The diagnostic efficiency did not differ between the groups in the learning phase [χ2 (3)=2.97, p=0.40]. The groups that received feedback spent between 30 and 60 s in each case reading the feedback.
Assessment: accuracy, efficiency, and diagnostic errors
Structured reflection is not superior to representation scaffold and is not superior to control (no scaffolding) with respect to accuracy (Table 3). All groups solved the same number of cases correctly [between 2.2 and 3.3 cases in the first assessment, χ2 (4)=8.40, p=0.08]. The assessment cases that had the same diagnoses as the cases in the learning phase were not solved more often by the scaffolding groups. The accuracy in all 15 cases is shown in Table 4.
Diagnostic efficiency did not differ between the groups [χ2 (4)=6.54, p=0.16]. None of the groups worked more efficiently than the others. However, during assessment 1, time on task was significantly shorter in the interventional groups compared to the control group [χ2 (4)=40.24, p=<0.001] with a strong effect size of Cohen’s d=1.16. Whereas the control group needed 45 min (SD=14), the other groups just needed between 24 and 30 min (SD=10–18) (see Table 5).
The diagnostic error distribution was different between groups (Table 3). Participants misdiagnosed 814 out of 2080 cases. In the first assessment, the error distribution differed between the groups. A lack of skills was the most common error in the two scaffolding groups without feedback. In the groups with feedback, misidentification and premature closure were the most frequent causes for diagnostic errors. In the control group, multiple error types were equally frequent. The most common diagnostic errors with regard to the medical content are shown in Table 6.
In assessment 2 (after a 1-week interval from assessment 1), the accuracy was similar in all groups [χ2 (4)=5.21, p=0.27] as was diagnostic efficiency [χ2 (4)=4.70, p=0.32]. Regarding time on task, the differences seen with the first assessment were no longer apparent [χ2 (4)=2.52, p=0.64]: All groups needed between 30 and 36 min (SD=7–20) to solve the cases. In assessment 2, the most important errors in all five groups were a lack of knowledge and premature closure (Table 7).
Result 1: Structured reflection is not superior to representation scaffold and not superior to control with respect to accuracy
While the degree of difficulty was sufficient to detect differences between the groups, diagnostic accuracy was similar across conditions. Neither representation nor structured reflections with or without feedback improved diagnostic accuracy. Why? There are many variables that can influence diagnostic accuracy and only a few of them are modified by scaffolding. To solve clinical cases, an adequate knowledge base , good diagnostic skills (e.g. interpretation of an electrocardiogram), and the correct interpretation and combination of clinical findings are obligatory . The feedback did not improve diagnostic accuracy. It is possible that the feedback was too short, too standardized, or that the students did not pay enough attention to it. Feedback has not been consistently effective in improving diagnostic accuracy .
Representation scaffolds and structured reflections did not improve diagnostic accuracy in the case scenarios we used. This corresponds to findings from other studies, which showed that groups which received instructional interventions are not more accurate than those that wrote down their first diagnostic idea . In a previous study, representation did not improve accuracy but did improve the diagnostic efficiency of medical students . The different results compared to another study  which studied the effects of reflection might be explained by a different degree of complexity of the cases. Our cases were quite complex, as they included 10 different diagnostic tests and distractors. In addition, our participants received the structured reflection prompt twice during case processing, while in the other study, the students used structured reflection only once at the end of the case.
Result 2: Representation scaffold is not superior to structured reflection and control with respect to efficiency
The time spent on the assessment cases was shorter in the scaffolding groups, but the shorter time on task did not translate into less accuracy. It has been shown that time pressure leads to less diagnostic accuracy , but simply solving cases faster without external pressure to do so does not cause more diagnostic errors.
The habituation to the learning environment in the learning phase may explain the shorter time on case in the scaffolding groups. The control group was as fast as the other groups in the second assessment. It is possible that it is not the interventions themselves but rather the learning with cases is helpful to decrease the time spent on a case.
Result 3: Diagnostic error distribution is different between groups
The distribution of the diagnostic errors was modified by the scaffolding in the first assessment. Groups that received feedback made more errors due to premature closure and misidentification. It is possible that the feedback led to increased confidence so that the students felt quite sure about their diagnoses in the assessments. Blissett and Sibbald pointed out that “collecting limited information may be described as efficient when the diagnosis is correct and as PCB (premature closure bias) when the diagnosis is incorrect” . We could not show an association between premature closure and time on task or efficiency in our study. The groups that received scaffolding and feedback misdiagnosed the most due to premature closure. In our study, students tend to collect almost all of the offered information, but information that is contradictory to their initial diagnosis cannot correct their diagnostic conclusions.
In the second assessment, the scaffolding did not influence the distribution of errors but specific cases were associated with certain kinds of errors. Diagnostic errors are at least partly content-dependent . This finding might be useful for further studies. If certain cases are associated with certain errors (for example, premature closure), those cases could be used for teaching purposes. Similar to the time spent on the cases, the effects on diagnostic error distribution were not reproduced in the second assessment.
As we used a laboratory setting with only one short intervention, we cannot comment on the transfer into educational field conditions. The feedback may not have been extensive enough to improve diagnostic performance. These scaffolding methods might be helpful in other expertise levels .
Conclusions and outlook
This is the first study that compared representation and reflection scaffolds and the influence of feedback on clinical reasoning in comparison to a control group.
All interventions failed to improve accuracy and efficiency in immediate and delayed assessment. This is an important finding: scaffolding methods, which have been successful in certain cases and settings, are not automatically effective in cases of a different complexity. The efficacy of scaffolding is likely influenced by the learner and the case. There is a lack of knowledge on how to adapt scaffolding to these circumstances. Prospective studies are needed to observe the influence of long-lasting courses with scaffolding. It remains unclear if the causes for diagnostic errors can be influenced by scaffolding.
In further studies, longer interventions and cases of differing complexity should be utilized.
In summary, in this randomized, controlled laboratory study of clinical reasoning in fourth and fifth year medical students, representation and reflection scaffolds did not improve diagnostic accuracy or reduce premature closure.
We are thankful to Laura Handgriff (Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, LMU) and Peter Musaeus (Centre for Health Sciences Education, Aarhus, Denmark) for critically proofreading the manuscript.
Anamnesis: Here it is important to pay attention to existing B-symptoms. There are also various risk factors for tuberculosis: immunosuppression, old age, travel to certain countries or the country of origin (Eastern Europe). Immunosuppressed patients are prone to reactivation of tuberculosis. The chronic course excludes acute pneumonia.
PE: Particular attention should be paid to the body temperature (sub-febrile) and the basally damped knocking sound, which suggests an infiltrate.
Patient record: In this case, an x-ray should be taken (DD: lung carcinoma). One can see here a miliary tuberculosis, which can occur especially in immuno-compromised patients. The lab indicates an infection. With the help of bacteriological examination the pathogen can be detected. The positive Ziehl-Neelsen stain is typical of mycobacteria.
The 61-year-old Mr. Hartmann complains of morning cough with whitish ejecta for a few months. In addition, he suffered from low breathlessness during physical exertion. Fever and night sweats are denied. Pre-existing conditions include hypertension treated with ramipril and a thiazide diuretic and simvastatin-treated hypercholesterolemia. He regularly drinks alcohol (2 beers/week) and has been smoking for over 40 years (about 60 packs per year).
In the physical examination, you make the following findings:
Awake, fully oriented, cognitively inconspicuous 61-year-old patient in good general condition and adipose nutritional status (100 kg, 1.86 m, BMI 30 kg/m2), affectionate and friendly, adequate verbal reaction.
Vital signs: blood pressure 150/95 mmHg, heart rate 82/min, respiratory rate 17/min, body temperature (ear) 36.6°C
Cardiovascular system: Heart sounds pure, rhythmic, no heart noises, no auscultated flow noises on the carotid. No jugular venous stasis, subtle peripheral edema. Peripheral pulse (A. radialis, A. dorsalis pedis, A. tibialis posterior) palpable.
Respiratory system: No chest deformities. Slight lip cyanosis. Hypersonic knocking sound on both sides, depending on respiration, 2 cm displaceable lung borders. Quiet breathing, bronchial breathing, no wet or dry secondary breath sounds. Thoracic spine not bumpy.
Abdomen: inspection unobtrusive. Bowel sounds vividly over all four quadrants, no abdominal flow noises. Soft abdominal wall, not painful palpation, no palpable resistance. Percussion normal knocking sound. Liver at inspiration with soft margin of the liver and without pain 3 cm caudal to the costal arch palpable, percussion 11 cm in the MCL. Spleen not palpable. No hernias. No kidney pox pain. Lumbar spine not bumpy.
Lymph nodes: no pathologically enlarged cervical, axillary, or inguinal lymph nodes palpable.
|Hemoglobin||14.0 g/dL||12.0–16.0 g/dL|
|Leukocytes||7.0 G/L||4.0–11.0 G/L|
|Thrombocytes||220 G/L||150–440 G/L|
|Creatinine||0.8 mg/dL||0.5–1.0 mg/dL|
|Sodium||139 mmol/L||135–145 mmol/L|
|Potassium||4.5 mmol/L||3.5–5.0 mmol/L|
|CRP||0.3 mg/dL||<0.5 mg/dL|
|SGOT||52 U/L||<33 U/L|
|SGPT||74 U/L||<35 U/L|
|γ-GT||45 U/L||<38 U/L|
|aPTT||28 s||23–35 s|
|Glucose||152 mg/dL||70–115 mg/dL|
|Urea||6.0 mmol/L||2.0–8.0 mmol/L|
|TSH||1.5 mU/L||0.4–2.5 mU/L|
|Chloride||98 mmol/L||96–110 mmol/L|
|Magnesium||1.05 mmol/L||0.70–1.20 mmol/L|
|Calcium||2.41 mmol/L||2.15–2.60 mmol/L|
|BSG||12 mm/h||Between 15 mm and 20 mm/h|
|Bilirubin||0.9 mg/dL||<1.0 mg/dL|
|Cholesterol/TAG||280 mg/dL||150–220 mg/dL|
|Ferritin||110 μg/L||23–217 μg/L|
|CK-MB||3 μg/L||<5 μg/L|
|Troponin T||0.08 ng/mL||<0.1 ng/mL|
|Uric acid||6.4 mg/dL||2.5–7.0 mg/dL|
|D-Dimer||220 ng/mL||<500 ng/mL|
|PCT||0.02 μg/L||<0.05 μg/L|
|Lactate||2.52 mmol/L||0.63–2.44 mmol/L|
Awake, fully oriented, cognitively inconspicuous 61-year-old patient with adequate verbal response.
No focal neurological deficit recognizable.
Motor skills: no latent or overt paresis with normal muscle tone
Reflexes: equally medically releasable (PSR, ASR, BSR) without widened reflex zones, Babinski negative
Sensitivity: intact in all qualities
Cranial nerves: cranial nerves intact, oculomotor unremarkable, no nystagmus
Gear and coordination: age-appropriate unremarkable
Cognition: MMST 30/30
Blood gas analysis
|pO2||58 mmHg||75–98 mmHg|
|pCO2||50 mmHg||35–45 mmHg|
|Standard bicarbonate||24||20–28 mmol/L|
|BE||−1||−2 to +2 mmol/L|
Lung function test
Aortic root normal wide. AK: age-related, opening movement normal, no insufficiency, no stenosis. RA: moderately enlarged (visually assessed). LA: moderately enlarged. RV: normal size, walls moderately thickened, normal RV function. LV: normal size, walls moderately thickened. Systolic global function low-normal (planimetric EF ~55%). No reg. Contraction disorders. Diastolic function normal. MK: age-related, movement normal, low insufficiency, no stenosis. TK: age-related, movement normal, low insufficiency, dpmax RV/RA=25 mmHg. VCI not dilated, breath modulated.
Summary: LVEF low-normal, visually assessed moderately enlarged RA, no relevant vitals, normal diastolic function.
Liver: image quality good. Size, normal, surface: smooth, echo pattern: condensed, no sound attenuation, vessel structures: normal, low-grade fat deposits (ICD-K76.0).
Gallbladder: well assessable, orthotopic, inconspicuous wall conditions, intraluminally no pathological echo structures, normal organ size.
Pancreas: body can be assessed with limited sensitivity, head and tail cannot be assessed during meteorism. Shape/contour: smooth, echo pattern: hypoechoic, pancreatic duct unrepresentable.
Spleen: Well assessable, normal size, echonormal homogenous internal reflex pattern, no focal changes, hilum free. Organ size: 105 mm×59 mm×42 mm, volume 136 mL.
Right kidney: easy to assess, orthotopic position, normal organ size, normal shape, age-related parenchyma, smooth organ contour, no urinary retention, no concrements. Size: 93 mm×55 mm×40 mm, volume 107 mL.
Left kidney: Well assessable, orthotopic position, normal organ size, normal shape, age-related parenchyma, smooth organ contour, no urinary retention, no concrements. Size: 94 mm×50 mm×37 mm, volume 91 mL.
Bladder: Well assessable, orthotopic, inconspicuous wall conditions, intraluminal no pathological echo structures, normal organ size.
Peritoneum: no ascites.
Prostate: normal findings.
Inconspicuous findings of the following abdominal organs: abdominal. Lymph nodes. Not assessable were: biliary tract.
Liver: low-grade fat deposits (ICD-K76.0)
Pancreas in strong air overlay only partially visible in the body. Other sonographic findings inconspicuous.
Material: sputum microscopy
Gram-positive cocci: negative Erythrocytes: negative Detritus: negative Leukocytes: negative Oral flora: +++
Evaluation: negative microbiological findings
Material: blood culture
Evaluation: negative microbiological findings
Amounts are: +++ a lot, ++ moderate amount, + little, (+) very little
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About the article
Published Online: 2019-02-18
Published in Print: 2019-06-26
Author contributions: LB contributed to the conceptual design of the study, the analysis and interpretation of the data, and the drafting of the manuscript. KB contributed to the study design and the collection of data and substantially contributed to the drafting of the manuscript. CL and DH substantially contributed to the study material and the drafting of the manuscript. JK contributed to the design of the study and the revision of the manuscript. MRF contributed to the conceptual design of the study, the interpretation of data, and the revision of the paper. RS contributed to the conceptual design of the study, the collection, analysis, and interpretation of data, and the drafting and revision of the paper. All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: Funds for this project were provided by the Friedrich-Baur-Institut, University Hospital, LMU Munich.
Employment or leadership: None declared.
Honorarium: None declared.
Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.