Proceedings of the 3 rd INFORMS Workshop on Data Mining and Health Informatics (DM-HI 2008) J. Li, D. Aleman, R. Sikora, eds. 1 A NURSING CARE PLAN RECOMMENDER SYSTEM USING A DATA MINING APPROACH Lian Duan Management Sciences Department University of Iowa Iowa City, IA lian-duan@uiowa.edu W. Nick Street Management Sciences Department University of Iowa Iowa City, IA Der-Fa Lu College of Nursing University of Iowa Iowa City, IA Abstract Recommender systems have been extensively studied to present items such as movies, music, and books that are likely of interest to the user. We propose to use correlations among nursing diagnoses, outcomes, and interventions to create a recommender system for constructing nursing care plans. Nursing care plan recommender systems can provide clinical decision support, nursing education, clinical quality control, and serve as a complement to existing practice guidelines. In the current study, we used nursing diagnosis data to develop the methodology. Our system utilizes a prefix-tree structure common in itemset mining to construct a ranked list of suggested care plan items based on previously-entered items. Unlike common commercial systems, our system makes sequential recommendations based on user interaction, modifying a ranked list of suggested items at each step in care plan construction. We rank items based on traditional association-rule measures such as support and confidence, as well as a novel measure that anticipates which selections might improve the quality of future rankings. Since the multi- step nature of our recommendations presents problems for traditional evaluation measures, we also present a new evaluation method based on average ranking position and use it to test the effectiveness of different recommendation strategies. Keywords: nursing care plan, recommender system, data mining. 1. Introduction and Related Work According to a report published in 2000 by the Institute of Medicine, at least 44,000 and perhaps as many as 98,000 patients die in the hospital each year as a result of medical errors alone [7]. These data point to adverse healthcare events as the leading cause of deaths in the US. Total national costs are estimated to be between $37.6 billion and $50 billion for adverse events and between $17 billion and $29 billion for preventable adverse events [7]. To contribute to the effectiveness, safety and efficiency of nursing care, we propose a nursing care plan recommender