Seite - 154 - in Applied Interdisciplinary Theory in Health Informatics - Knowledge Base for Practitioners

journal of their own activities and goals, and are periodically re-evaluated for their stage of change. The intervention was tested in a controlled study with 32 participants, where the control group received a delayed intervention (started after the study outcomes were measured). In the 16-week program, activity increased by 1384 steps/day (p=0.03) in the intervention group, compared to 816 steps/day (p=0.14) for the control group. Waist circumference decreased in the intervention group but not in the control group (a change of -4.0 cm vs +0.6 cm; p < 0.05) and Coronary Risk Ratio reduced in the intervention group (from 5.1 to 4.7; p=0.04) while remaining constant in the control group (3.7; p=0.94). 3. Explanation of the success or failure of use of health behaviour and behaviour change theory in health IT systems In a review of internet-based behaviour change interventions, Webb et al. found that use of theory was positively associated with effect size [3]. Three theories were used most often: the Theory of Planned Behaviour, Transtheoretical model, and Social-Cognitive theory. Figure shows the effect sizes for studies that used these theories, as well as the effect for studies that used behaviour change theories in different ways. Using theory or predictors for participant selection was associated with a larger increase in effect size than using it for intervention design, and using it for both purposes had the greatest effect [3]. All three of the interventions described above made use of theory to develop the content of their interventions. Presenting tailored information (in other words, incorporating specific data about the user/patient to determine what kind of support should be provided) also showed a small positive effect. The Tailored Print application and the Active Living Every Day intervention are examples of this application of theory. Theory can also be applied to explain or predict observed behaviour. For example, clinicians' intention to use each of seven information sources to learn about a new drug was examined in a survey based on the Reasoned Action Approach. In this study, attitudes were shown to have a greater influence than subjective norms for this behaviour [23]. Theory can also be misapplied, e.g. by applying it out of the context in which it was developed and tested. An example of this is an attempt to use "credibility cues", based on Fogg's work on credibility, persuasion, and behaviour change, to encourage people to register as an organ donor via a website [24]. Fogg’s theory, based on many empirical studies of eCommerce websites, states that website credibility is based on the user's perception that the people behind a website are trustworthy and have relevant expertise. This means a site design should be: professional; make it easy to verify the information it contains; show that behind the site is a real organisation with people who have relevant expertise, are honest and trustworthy and can be contacted if need be; easy to use, useful and frequently updated; and that the site design avoids errors of all kinds and promotional content. 4 S.MedlockandJ.C.Wyatt /HealthBehaviourTheory inHealth Informatics154