suggested that the number of people subscribing to mobile cloud applications will rise from 71 million to nearly a billion by 2014 [49]. In health sectors, many organizations, managers, and experts believe that the cloud computing approach can also improve services and benefit research [8-13]. In addition, a report by the European Network and Information Security Agency (ENISA) stated that this new computing model is set to see massive global investment in many sectors, including health care [50]. The report also estimated that, by 2013, US $44 billion will be spent worldwide on cloud computing, potentially providing huge benefits to health care.
As with any innovation, cloud computing should be rigorously evaluated before its widespread adoption. Few research papers have systematically studied the impact of cloud computing on health care IT in terms of its opportunities and challenges. This study reviews the literature and evaluates the opportunities and challenges from the viewpoint of management, technology, security, and legality (see Table 1).