Naive Bayes Classification of Public Health Data with Greedy Feature Selection
Hickey, Stephanie J., Communications of the IIMA
Public health issues feature prominently in popular awareness, political debate, and in data mining literature. Data mining, the work of discovering patterns in data, has the potential to influence public health in a myriad of ways, from personalized, genetic medicine to studies of environmental health and epidemiology, and many applications in between. Classification of new data based on patterns previously observed holds promise for applying specific advances to public health more generally. Classification algorithms that take advantage of Bayes' Theorem and prevalence statistics, dubbed naive Bayes classifiers, aim to accomplish this with readily available data.
For this study, we applied a naive Bayes classifier to a robust public health dataset, with greedy feature selection, with the objective of efficiently identifying that the n attributes which best predict a selected target attribute, without searching the input space exhaustively. For example, is length of hospital stay impacted by insurance type, by region, by type of hospital, or by something else? Do diagnoses and procedures drive outcomes (discharge status) or does something else?
This study may contribute toward applying data mining approaches to public health data, specifically, to predicting attributes that represent a measure of treatment outcome or a proxy for cost, for patients receiving health care services in U.S. hospitals, based on readily accessible patient data.
PUBLIC HEALTH CARE IN THE U.S.
The U.S. health care system has had no shortage of attention recently. According to the World Health Organization, health care spending amounted to $7,146 per capita and 15.2% of the gross domestic product in 2008, the highest of any nation. In its World Health Report 2000, its most recent survey of population health and health systems financing, however, the U.S. ranked 38th. As recently as 2010, 49.9 million residents had neither public nor private insurance to help allay the cost of health care (1). The debate surrounding the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010, designed to extend insurance options to more residents and curtail further increases in health-care spending, was a major issue in the 2012 elections. Yet, despite the attention, apparent tradeoffs between the costs of health care, both to individuals and institutions, the quality of care received by most patients, and the efficiency of the system as a whole persist.
The recent explosion in data available for analysis is as evident in health care as anywhere else. Private and public insurers, health care providers, particularly hospitals, physician groups and laboratories, and government agencies are able to generate far more digital information than ever before. This data presents an opportunity; clues to the varied challenges faced by the health care system may lie in this data. The insights gained from effectively mining public health data have implications for several types of stakeholders in the current health care system: planning implications for hospital administrators, treatment protocol implications for physician groups, public health implications for legislators, government agencies, and think tanks.
Not surprisingly, a great deal of data mining analysis is being done in the public health domain, particularly predictive data mining in clinical medicine (Bellazzi & Zupan, 2008), and the potential influence of such work is broad and compelling (Kulikowski, 2002). Further, data mining in the public health domain presents unique challenges (Cios & Moore, 2002): heterogeneity of medical data, ethical, legal, and social constraints on use of that data, statistical approaches that address heterogeneity and these constraints, and the special status of medicine as a revered and scrutinized field responsible for life-and-death decisions that may affect all of us. …