The role of risk and benefit perception in informed consent for surgery

Informed consent relies on patients' ability to understand risk information. Evidence suggests that people may extract the gist of any risk information to make medical decisions. Existing evidence also suggests that there is an inverse relationship between the perception of risk and the perception of benefit.

Seventy-one patients on the waiting list for carotid endarterectomy (CEA) were surveyed regarding their understanding and recall of the risk and benefit to health of undergoing CEA. Patients were surveyed 1 month after their initial consultation, and a subgroup was surveyed again on the day before their operation.

Patients' estimates of their baseline risk of stroke without surgery were significantly different from what they had been told by the surgeon. Patients' estimates of stroke risk due to surgery ranged from 0% to 65% (actual local risk 2%). Patients also had unreasonable expectations about the benefit of the operation for their health. Estimates of stroke risk correlated positively with the degree of expected benefit from the operation (r = 0.29, P = 0.05). When resurveyed the day before the operation, patients' perceptions of both risk and benefit had increased significantly. The risk perception data from some patients appeared to contradict some of the predictions of the fuzzy-trace theory.

Most patients failed to understand the risks and benefits associated with CEA. Some patients' estimates of stroke risk were actually greater than the perceived potential benefit of surgery in terms of risk reduction. The data also suggested a positive correlation between the degree of perceived benefit and the degree of perceived risk.