Biomedical Question Answering: A Survey of Approaches and Challenges

Professionals as well as the general public need effective assistance to access, understand and consume complex biomedical concepts. For example, doctors always want to be aware of up-to-date clinical evidence for the diagnosis and treatment of diseases under the scheme of Evidence-based Medicine [165], and the general public is becoming increasingly interested in learning about their own health conditions on the Internet [54]. Traditionally, Information Retrieval (IR) systems, such as PubMed, have been used to meet such information needs. However, classical IR is still not efficient enough [71, 77, 99, 164]. For instance, Russell-Rose and Chamberlain [164] reported that it requires 4 expert hours to answer complex medical queries using search engines. Compared with the retrieval systems that typically return a list of relevant documents for the users to read, Question Answering (QA) systems that provide direct answers to users' questions are more straightforward and intuitive. In general, QA itself is a challenging benchmark Natural Language Processing (NLP) task for evaluating the abilities of intelligent systems to understand a question, retrieve and utilize relevant materials and generate its answer. With the rapid development of computing hardware, modern QA models, especially those based on deep learning [30, 31, 42, 146, 171], achieve comparable or even better performance than human on many benchmark datasets [67, 83, 154, 155, 215] and have been successfully adopted in general domain search engines and conversational assistants [150, 236]. The Text REtrieval Conference (TREC) QA Track has triggered the modern QA research [197], when QA models were mostly based on IR.