Abstract—Population aging has brought important challenges at social, economical, and healthcare issues, mainly due to the increasing number of people that need intensive care. Ambient Assisted Living (AAL) systems that aim at assisting people in their health-related activities have emerged. In another perspective, Reference Architectures (RAs) are a special type of software architecture that promotes reuse of design expertise and facilitates the development, standardization, and evolution of software systems. During the last years, important RAs for AAL systems have been created. However, there is a lack of studies that compare RAs for healthcare systems in AAL domain, making the selection among RAs a rather difficult task. In this paper, we present a comparative analysis and evaluate the completeness of that healthcare RAs. Specifically, we intend to offer: (i) a guide to select the most complete and adequate RA for software projects; and (ii) to describe research directions to i...