Decision complexity affects the extent and type of decision support use.

The increasing complexity of decision-making has emerged as a risk factor in clinical medicine. The impact that decision task complexity has on the uptake and use of clinical decision support systems (DSS) is also not well understood. Antibiotic prescribing in critical care is a complex, cognitively demanding task, made under time pressure. A web-based experiment was conducted to explore the impact of decision complexity on DSS utilization, comparing utilization of antibiotic guidelines and an interactive probability calculator for ventilator associated pneumonia (VAP) plus laboratory data. Decision support was found to be used more often for less complex decisions. Prescribing decisions of higher complexity were associated with a lower frequency of DSS use, but required the use of the more cognitively demanding situation assessment tool for infection risk along with pathology data. Decision complexity thus seems to impact on the extent and type of information support used by individuals when decision-making.