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Bayes Theorem? There's an App for That


A hospitalist at Beth Israel Deaconess Medical Center in Boston has created an iPhone application to help give academic HM groups fingertip access to Bayesian nomograms and real-time research.

Hospitalist Elizabeth Farrell, MD, says an app dubbed Medicine Toolkit ( should be available for download in a matter of weeks. The app has two components. The first is Bayes at the Bedside, a database of likelihood ratios (LRs) for more than 150 commonly used physical exam findings, labs, and imaging studies paired with an automated Bayesian nomogram to visually display the theorem and its application to clinical decision-making. The second piece of the program is Pocket Evidence, a compilation of more than 300 review articles, consensus guidelines, meta-analyses, and new and notable articles. Both components will be updated monthly.

“I really am envisioning it as a teaching tool and one that could be used by attendings to teach residents, interns, and medical students alike to facilitate critical thinking and evidence-based medicine,” Dr. Farrell says. “It can be used on rounds, in the clinic, or in the classroom.”

Dr. Farrell, a hospitalist for two years, had the idea to develop the application after printing out nomograms on index cards to use on rounds. She gave cards to team members and printed LRs on the back.

“It was a lot of fun, the team loved it, it worked great,” Dr. Farrell says. “But a lot of times I’d find that I ran out of the index cards, or someone on the team left theirs back in the workroom, or we didn’t have the LR for the test we were talking about. It resulted in a lot of missed teaching opportunities.”

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