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Evaluation of PICO as a knowledge representation for clinical questions
The paradigm of evidence-based medicine (EBM) recommends that physicians formulate clinical questions in terms of the problem/population, intervention, comparison, and outcome. Together, these elements comprise a PICO frame. Although the framework was developed to facilitate formulation of clinical questions, the ability of PICO structures to represent physicians' information needs has not been empirically investigated. This paper evaluates the adequacy and suitability of PICO frames as a knowledge representation by analyzing 59 real-life questions in primary care. We discovered that only two questions in our corpus contained all four PICO elements, and that 37% of questions contained only intervention and outcome. Results revealed structural frame patterns that cluster according to the type of clinical question, i.e., therapy, diagnosis, prognosis, and etiology. We found that the PICO framework is primarily centered on therapy questions, and is less suited to representing other types of clinical information needs. Challenges in mapping natural language questions into PICO structures are also discussed. Although we point out limitations of the PICO framework, our study as a whole reaffirms its value as a tool to assist physicians practicing EBM.