The potential advantages of using the Internet to deliver self-care and behavior-change programs are well recognized. An aging population combined with the increasing prevalence of long-term conditions and more effective medical interventions place financial strain on all health care systems. Web-based interventions have the potential to combine the tailored approach of face-to-face interventions with the scalability of public health interventions that have low marginal costs per additional user. From a patient perspective, Web-based interventions can be highly attractive because they are convenient, easily accessible, and can maintain anonymity/privacy. Recognition of this potential has led to research in developing and evaluating Web-based interventions for self-management of long-term conditions and behavior change. Numerous systematic reviews have confirmed the effectiveness of some Web-based interventions, but a number of unanswered questions still remain. This paper reviews the progress made in developing and evaluating Web-based interventions and considers three challenging areas: equity, effectiveness, and implementation. The impact of Web-based interventions on health inequalities remains unclear. Although some have argued that such interventions can increase access to underserved communities, there is evidence to suggest that reliance on Web-based interventions may exacerbate health inequalities by excluding those on the "wrong" side of the digital divide. Although most systematic reviews have found a positive effect on outcomes of interest, effect sizes tend to be small and not all interventions are successful. Further work is needed to determine why some interventions work and others do not. This includes considering the "active ingredients" or mechanism of action of these complex interventions and the context in which they are used. Are there certain demographic, psychological, or clinical factors that promote or inhibit success? Are some behaviors or some clinical problems more amenable to change by computer-based interventions? Equally problematic is the issue of implementation and integration of such programs into routine clinical practice. Many eHealth projects end when the research is concluded and fail to become part of mainstream clinical care. One way of addressing these challenges is to apply the Medical Research Council framework for developing, evaluating, and implementing complex interventions. This includes having a strong theoretical foundation, developing a proposed mechanism or pathway of action, ensuring that the evaluation adequately reflects this proposed pathway, and considering implementation from the beginning of the development process.
Keywords: Internet; eHealth; health behavior; self-care.