A Study to Evaluate Strategies for Teaching Effective Use of Diagnostic Tests

Sentara Norfolk General Hospital

Status: Completed

Conditions: Instructional Methods

Treatments: Other: Conceptual teaching

Study type: Interventional

Funder types: Other

Identifiers

NCT04130607

18-04-EX-0062

Details and patient eligibility

About

A recent Institute of Medicine monograph brought attention to high rates of diagnostic error and called for better educational efforts to improve diagnostic accuracy.1 Educational methods, however, are rarely tested and some educational efforts may be ineffective and wasteful.2 In this study, we plan to examine whether explicit instruction on diagnostic methods will have an effect on diagnostic accuracy of 2nd-year medical students and internal medicine residents.

Full description

Research has shown that expert diagnosticians use a two-step process to confirm a diagnosis: hypothesis generation to generate diagnostic possibilities, followed by hypothesis verification to confirm the most likely diagnostic possibility.3-5 The first step appears to be non-analytical, related to pattern recognition. The second step could be calculated using analytical reasoning, however, physicians rarely make an overt calculation of conditional probabilities. Instead, experienced clinicians typically use an implicit habit or heuristic called "anchoring and adjusting" to incorporate diagnostic testing information into their thinking.6,7 Cognitive psychologists have postulated that anchoring and adjusting provides a way that probability estimates can be updated based on additional new evidence. Most of the discussion in the literature focuses on how this heuristic can lead to biased thinking because of base-rate neglect or anchoring.6 Very little discussion is on how this heuristic could be improved to yield more accurate probability estimates and whether proper use of the heuristic could be taught.

The degree to which a diagnostic test should lead to an adjustment of a probability estimate depends on the operating characteristics of a test, that is, the sensitivity and specificity. Likelihood ratios, once understood, are easier to incorporate into one's thinking, and thus could be used to calibrate the anchoring and adjusting heuristic.7

In this randomized trial, we tested whether explicit conceptual instruction on Bayesian reasoning and likelihood ratios would improve Bayesian updating, compared with a second intervention where we provided multiple (27) examples of clinical problem solving. The third arm provided minimal teaching about diagnosis, but no explicit teaching or examples.

Enrollment: 65 patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion and exclusion criteria

Inclusion Criteria:

• Medical Student at McMaster University or Eastern Virginia Medical School
• Completed 18 months of coursework

Trial design

Primary purpose: Health Services Research

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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65 participants in 3 patient groups, including a placebo group

Analytical

Experimental group

Description:

Students will receive brief instruction in probability, sensitivity, specificity, and likelihood ratios, with distributions and calculations. Pretest and posttest probabilities will be computed for two cases for each of the three conditions listed above.

Treatment:

Other: Conceptual teaching

Experiential

Active Comparator group

Description:

Students will receive a brief instruction conceptually discussing sensitivity and specificity (e.g. "a sensitive test will be positive at even low levels of disease. However, this can lead to a number of false positive errors, when the test is positive even when there is no disease. As a result, it is most useful for ruling out a diagnosis"). They will then work through a total of 30 cases, 10 for each condition, in blocked sequence. For each brief written case they will be asked for a probability of diagnosis after the clinical information is presented. The test result will then be given and they will be asked for a post-test probability. Their estimate will be compared to the computed value based on published estimates of sensitivity and specificity and feedback provided.

Treatment:

Other: Conceptual teaching

No Explicit Instruction or Examples

Placebo Comparator group

Description:

Students will receive 3 passages from a clinical text related to each of the 3 conditions in the study and asked to study them for 15 min each.

Treatment:

Other: Conceptual teaching