  This study assesses the ability of state-of-the-art large language models
(LLMs) including GPT-3.5, GPT-4, Falcon, and LLaMA 2 to identify patients with
mild cognitive impairment (MCI) from discharge summaries and examines instances
where the models' responses were misaligned with their reasoning. Utilizing the
MIMIC-IV v2.2 database, we focused on a cohort aged 65 and older, verifying MCI
diagnoses against ICD codes and expert evaluations. The data was partitioned
into training, validation, and testing sets in a 7:2:1 ratio for model
fine-tuning and evaluation, with an additional metastatic cancer dataset from
MIMIC III used to further assess reasoning consistency. GPT-4 demonstrated
superior interpretative capabilities, particularly in response to complex
prompts, yet displayed notable response-reasoning inconsistencies. In contrast,
open-source models like Falcon and LLaMA 2 achieved high accuracy but lacked
explanatory reasoning, underscoring the necessity for further research to
optimize both performance and interpretability. The study emphasizes the
significance of prompt engineering and the need for further exploration into
the unexpected reasoning-response misalignment observed in GPT-4. The results
underscore the promise of incorporating LLMs into healthcare diagnostics,
contingent upon methodological advancements to ensure accuracy and clinical
coherence of AI-generated outputs, thereby improving the trustworthiness of
LLMs for medical decision-making.
