Optimising large language models for clinical information extraction: a benchmarking study in the context of ulcerative colitis research
Bibliographic record
Abstract
Objective: Closed-source large language models (LLMs) like generative pre-trained transformer 4o (GPT-4o) have shown promise for clinical information extraction but are potentially limited by cost, data security concerns and inflexibility. Open-source models are an attractive alternative with various adaptation strategies with no consensus on best practices. This study aims to rigorously identify optimal adaptation strategies for open-source models and evaluate their performance relative to closed-source alternatives. Methods and Analysis: We studied three LLM adaptation strategies: chain-of-thought prompting, few-shot prompting and fine-tuning. Our target for information extraction was the Mayo Endoscopic Subscore (MES). We applied those strategies in all combinations to six open-source models (8-70 billion parameters) using an annotated set of colonoscopy procedure reports from the University of California, San Francisco (N=608) and San Francisco General Hospital (N=217). We analysed the relationship of these strategies to several performance metrics with a mixed-effects model, accounting for the variability between centres and LLMs. GPT-4o served as a closed-source oracle and provided in-depth commentary on the cost-effectiveness of these options. Results: < 0.001) the performance of open-source LLMs by 9.1-15.7 percentage points across accuracy, precision recall and annotation eligibility accuracy. However, GPT-4o with prompt engineering outperforms the best open-source model by 4.9%-11.2%. A simple cost-effectiveness analysis suggests that GPT-4o is more affordable compared with open-source alternatives. Conclusion: GPT-4o is currently the most efficient LLM for MES extraction. If unavailable, QLoRA-optimised open-source models are a competitive alternative. However, results also suggest that current instruction-following LLMs including GPT-4o do not fully follow user-provided instructions, leaving room for improvement. More work is needed to achieve consistent, near-perfect performance in clinical information extraction by LLMs.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.019 | 0.062 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".