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Advancing Evidence-Based Medicine for Population, Intervention, Comparison, and Outcome Element Recognition and Extraction in Medical Literature: Large Language Model Approach

Hao Z, Duan Y, Wang Y

Journal of medical Internet research, 2026

Abstract

Background: The exponential expansion of biomedical literature has created an urgent need for efficient methods to recognize and extract population, intervention, comparison, and outcome (PICO) elements-the foundational elements of evidence-based medicine.

Objective: This study systematically evaluated 2 complementary approaches for automating PICO recognition and extraction in medical literature: prompt engineering optimization and parameter-efficient fine-tuning (PEFT) of large language models (LLMs).

Methods: We developed a dual-phase methodological framework: (1) systematic prompt optimization incorporating in-context learning, chain of thought (COT), and multipath reasoning strategies; and (2) PEFT of the LLM architecture using low-rank adaptation (LoRA), quantized LoRA, and freeze techniques. The PubMed-PICO and NICTA-PIBOSO benchmark datasets were used for recognition tasks, and the EBM-NLP dataset was used for extraction tasks. Performance metrics included precision, recall, and F1-score. F1-score was adopted as the major metric as it balances precision and recall.

Results: For prompt engineering, COT achieved the overall best performance across both recognition and extraction tasks. For example, in the recognition task, COT obtained strong average F1-scores of 77.1% (SD 0.5%) for the population element and 84.5% (SD 0.4%) for the outcome element on PubMed-PICO. In the extraction task, COT achieved the highest average F1-score of 73.9% across 3 PICO elements (the…

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