Design factors for success or failure of guideline-based decision support systems: an hypothesis involving case complexity.

Computer-based decision support systems (CDSSs) are currently mostly reminder systems. However, the effectiveness of such systems to modify physician behavior is not always observed. We assume that this approach is appropriate when physicians think they know how to prescribe and consider they don't need to be helped, i.e. for simple clinical cases. On the opposite, on-demand approaches allowing for flexibility in the interpretation of patient conditions are more appropriate for more complex cases, e.g. in chronic disease management. ASTI is a CDSS operating in two modes, a critiquing mode working as a reminder-based system and a user-initiated guiding mode. Using a clinical case complexity score, a pre/post-intervention experiment with 10 GPs and 15 cases of hypertensive patients has been performed. Preliminary results tend to indicate that reminder-based interaction is appropriate for simple cases and that physicians are willing to use on-demand systems as clinical situations become complex, making both modes complementary.