Larger numbers of physicians are using the Internet to locate and seek medical information and it has been suggested that one of its greatest benefits is as a tool for professional development [1–3]. Internet-based learning has become an increasingly popular approach to medical education [4–6] and Internet-based continuing medical education (CME) has grown steadily in the recent past [7, 8]. The Internet has expanded opportunities for the provision of a flexible, convenient and interactive form of CME that has fulfilled the requirements of busy practitioners who have difficulty attending formal education sessions [9, 10].
Internet-based CME has been associated with favorable outcomes across a wide variety of learners, learning contexts, clinical topics and learning outcomes . According to Wearne,  these programs can vary in style, content, relevance, reliability, authorship and sponsorship, and hence educational quality. A variety of Internet technologies, instructional methods and presentation formats are being used to provide both asynchronous and synchronous forms of Internet-based CME . Internet-based CME is commonly offered, although not exclusively, through the use of learning management systems (LMS) and web conferencing systems. A learning management system is software for delivering, tracking and managing Internet-based education and often includes features for learning assessment and online collaboration (e.g. chat, discussion board and e-mail). Web conferencing systems can facilitate synchronous presentations via the Internet. Participants are connected with other participants through their computer and can view real-time presentations while interacting with a presenter over a standard telephone line or Voice over Internet Protocol (VoIP) audio technology. Some systems also include whiteboards, chat and polling features. In a systematic review of Internet-based CME literature, Cook et al. found that Internet-based instruction addresses a wide range of topics with most interventions involving tutorials for self-study or virtual patients, and over a quarter requiring online discussion with peers, instructors or both.
The main benefits of Internet-based CME include: improved access, convenience and flexibility; reduced travel expenses and time; adaptability to learning styles; just-in-time learning; and an interactive multimedia format [5, 6, 11, 12]. Curran and Fleet's  review of Internet-based CME evaluation literature found that physicians are generally satisfied with it and in some instances more satisfied than with traditional CME formats. Wutoh et al.  also reviewed the evaluation literature and concluded that Internet-based CME is as effective in imparting knowledge as traditional formats of CME. Cook et al.'s  systematic review found that Internet-based learning is educationally beneficial and can achieve results similar to those of traditional instructional methods. This review also suggested that effective learning outcomes appeared to be associated with cognitive interactivity, peer discussion, on-going access to instructional materials and practice exercises .
It has been suggested that further research comparing Internet-based interventions against no-intervention comparison groups is of little value . Further research in the field should investigate elements of Internet-based CME that could make it more effective and efficient, such as specific instructional methods, presentation formats, and approaches to implementation . According to Cook et al.  examining how to effectively implement Internet-based instruction must involve research directly comparing different Internet-based interventions. Curran and Fleet  have also suggested the need to examine in greater detail the nature and characteristics of those Internet-based learning technologies, environments and systems which are most effective. There are limited comparative studies of this nature reported in the Internet-based CME literature [2, 5]. In one study, Beal et al.  compared the effectiveness of different curriculum delivery strategies (e.g., e-mail versus web site) and duration of delivery in providing Internet-based CME. They found no significant difference in knowledge, confidence and communication by curriculum delivery strategy.
A number of other studies have examined the specific use of both asynchronous technologies (e.g., e-mail, discussion boards) and synchronous technologies (e.g., Web conferencing) for facilitating Internet-based CME and the results have been generally mixed . A number of authors report findings on the effectiveness of Internet-based CME facilitated by way of electronic mail or online discussion boards, however do not compare these approaches to other Internet-based interventions [14–17]. In one study, live CME participants made very little use of either e-mail or telephone to contact faculty, however 85% of online CME participants signed on at some point in time during web conferencing sessions . Guan et al.  examined physicians' participation in online learning discussions, perceptions of online social closeness, and barriers and motivators to participation. Lack of time and peer response were given as the main reasons for low participation in learning discussions. Weir et al.  also studied the effectiveness of an e-mail based discussion forum using clinical cases as stimulus material. Message postings from 27 participants were most frequent during the first of four weeks and lowest during the second. Curran et al.  examined the nature of the interactions and collaborative learning characteristics exhibited in Internet-based CME that included asynchronous, text-based computer discussion. The results suggested that the nature of participation consisted primarily of independent messages with a minimal amount of learner-to-learner interaction .
While the literature examining the use of asynchronous communications (e.g. e-mail, discussion boards) in Internet-based CME is suggestive of some limitations in its use, the principles for supporting the use of such approaches is strongly supported by adult learning theory. One theory in particular, social constructivism, views learning to be an active rather than passive endeavor. Social constructivists propose that learning is a dialogic process in which communities of practitioners engage socially in talk and activity about shared problems or tasks [21, 22]. Learning occurs through engaging, incorporating and critically exploring the views of others, while new possibilities of interpretations are opened through the interaction . Making meaning is the ultimate goal of constructivist learning processes [23, 24], and to make meaning, constructivists believe that learners must be encouraged to articulate and reflect on what they know. Asynchronous communications are a critical component in the design of Internet-based constructivist learning environments (CLEs) as such technologies, if used effectively, can foster interaction, collaboration, and knowledge building. The communicative learning approaches which can be facilitated enable adult learners to participate in a collaborative process of building and reshaping understanding with and among their peers [25, 26].
The purpose of the study described in this paper was to conduct a comparative evaluation of two differing Internet-based CME delivery strategies and the effect of a scheduled delivery format and facilitator-led asynchronous discussion instructional strategy on satisfaction, knowledge and confidence outcomes.