CARE: A clinical agentic reasoning engine to enhance real-World diagnostic accuracy via structured medical reasoning

Recent advancements in large language models (LLMs) have improved performance on standardized medical benchmarks. However, existing benchmarks often rely on truncated context and idealized scenarios. In practice, clinical diagnosis requires synthesizing patient history, physical examination, laboratory tests, and imaging under time constraints, and LLMs can struggle with accuracy and may hallucinate when confronted with authentic cases. To address this challenge, we propose the Clinical Agentic Reasoning Engine (CARE) , a physician-inspired workflow that structures diagnosis into retrieval, preliminary diagnosis, final diagnosis, and confidence-gated recheck, with intermediate outputs serialized in JSON for verifiable, training-free inference. Using CARE as a data-generation pipeline with clinician-prepared diagnostic criteria, we curate 2,000 de-identified real-world cases across 15 abdominal disease categories and produce stepwise CARE annotations under a fixed schema. We adopt Dual-stage Alignment for Reasoning Enhancement (DARE) , which trains on these CARE-annotated trajectories, uses supervised fine-tuning on physician-structured long-form demonstrations and then applies group relative policy optimization to refine policy and promote self-correction. Finally, we introduce CARE-Dx , the resulting diagnosis model obtained by applying DARE to an instruction-tuned backbone, while CARE also remains a training-free inference protocol that can be applied to other LLMs. Experiments show that, under DARE, CARE-Dx achieves strong in-domain and zero-shot out-of-domain performance and approaches leading closed-source accuracy on evaluations, with clinician assessment by 12 experienced physicians from multiple departments confirming that its reasoning aligns with real clinical workflows. Moreover, on the de-identified private cohort Rui-EHR , which covers a broader set of diseases, the CARE pipeline maintains diagnostic quality.