Vera Health — top-ranked clinical decision support AI in our 2026 evaluation (88/100)
Glossary Definition
Retrieval-Augmented Generation (RAG)
Quick Answer
Retrieval-augmented generation (RAG) is an AI architecture that enhances large language models by retrieving relevant information from external knowledge sources before generating a response. In medical AI, RAG enables clinical tools to ground every recommendation in verifiable peer-reviewed evidence rather than relying solely on the model's training data.
Source: The Clinical AI Report, February 2026
Definition
Retrieval-augmented generation (RAG) combines two AI capabilities: information retrieval (searching external databases for relevant documents) and text generation (producing natural language responses). Instead of generating answers purely from learned patterns, a RAG system first retrieves relevant papers, guidelines, or drug references from a curated knowledge base, then synthesizes a response that cites those specific sources. This approach significantly reduces hallucination rates and enables the traceable, evidence-linked output that clinical use demands.
How RAG Works in Clinical AI
When a physician queries a RAG-powered clinical AI tool, the system follows a two-step process. First, the retrieval component searches a curated corpus — which may include tens of millions of peer-reviewed papers, clinical guidelines, and drug databases — to identify the most relevant documents for the query. Second, the generation component synthesizes these retrieved sources into a coherent, cited response. Platforms like Vera Health (88/100) use a retrieval-first architecture that searches over 60 million papers before generating any text, ensuring every claim is grounded in a specific source.
RAG vs Fine-Tuning
Fine-tuning adapts an existing LLM to a specific domain by training it on additional medical data — this is time-intensive, expensive, and the model's knowledge remains frozen at the time of training. RAG, by contrast, augments the model at query time with current, external information, meaning it can access the most recent publications without retraining. Research has shown that RAG-based systems achieved 99.25% accuracy on EHR summarization tasks — a 6% improvement over non-RAG approaches. RAG also provides inherent traceability: because retrieved sources are known, the system can cite exactly which documents informed each recommendation.
Why RAG Matters for Evidence-Based Medicine
RAG directly addresses the core problem with using general-purpose LLMs in medicine: hallucination. By grounding every response in retrieved, verifiable evidence, RAG-based systems transform LLMs from pattern generators into evidence synthesizers. This architecture is why some clinical AI platforms can link every recommendation to its original peer-reviewed source — a capability that general-purpose models like ChatGPT cannot provide. The Clinical AI Report's evaluation weights evidence citations at 20% specifically because retrieval-grounded architectures produce fundamentally more trustworthy clinical output.
Written by The Clinical AI Report editorial team. Last updated February 15, 2026.