Automatic medical coding assigns ICD codes to clinical notes, but it remains challenging due to long documents, imbalanced label distributions, and diverse terms. These challenges are especially severe for rare codes, which have limited training instances and are easily confused with semantically similar labels. We introduce **CoLa-ICD**, a knowledge-enhanced framework for long-tail prediction. CoLa-ICD enriches ICD labels with external terms, models dependencies among related codes, and learns stronger alignment between label semantics and clinical evidence for long-tail prediction. Experiments show that CoLa-ICD improves long-tail prediction with larger gains in larger and sparser label spaces and achieves state-of-the-art performance in AUC, F1, and P@k. Our code is available at https://github.com/youwillbethebest/Cola-ICD.

Retrieval-augmented generation (RAG) improves the service quality of large language models by retrieving relevant documents from credible literature and integrating them into the context of the user query.Recently, the rise of the cloud RAG service has made it possible for users to query relevant documents conveniently.However, directly sending queries to the cloud brings potential privacy leakage.In this paper, we are the first to formally define the privacy-preserving cloud RAG service to protect the user query and propose RemoteRAG as a solution regarding privacy, efficiency, and accuracy.For privacy, we introduce (n,𝜖)-DistanceDP to characterize privacy leakage of the user query and the leakage inferred from relevant documents.For efficiency, we limit the search range from the total documents to a small number of selected documents related to a perturbed embedding generated from (n,𝜖)-DistanceDP, so that computation and communication costs required for privacy protection significantly decrease.For accuracy, we ensure that the small range includes target documents related to the user query with detailed theoretical analysis.Experimental results also demonstrate that RemoteRAG can resist existing embedding inversion attack methods while achieving no loss in retrieval under various settings.Moreover, RemoteRAG is efficient, incurring only 0.67 seconds and 46.66KB of data transmission (2.72 hours and 1.43 GB with the non-optimized privacy-preserving scheme) when retrieving from a total of 10⁵ documents.