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

Background. Informed consent relies on patients' ability to understand risk information. Evidence suggests that people may extract the gist of any ris k information to make medical decisions. Existing evidence also suggests th at there is an inverse relationship between the perception of risk and the perception of benefit. Method. Seventy-one patients on the waiting list for carotid endarterectomy (CEA) were surveyed regarding their understanding a nd recall of the risk and benefit to health of undergoing CEA. Patients wer e surveyed 1 month after their initial consultation, and a subgroup was sur veyed again on the day before their operation. Results. Patients' estimates of their baseline risk of stroke without surgery were significantly differ ent from what they had been told by the surgeon. Patients' estimates of str oke risk due to surgery ranged from 0% to 65% (actual local risk 2%). Patie nts also had unreasonable expectations about the benefit of the operation f or their health. Estimates of stroke risk correlated positively with the de gree of expected benefit from the operation (r = 0.29, P = 0.05). When resu rveyed the day before the operation, patients' perceptions of both risk and benefit had increased significantly. The risk perception data from some pa tients appeared to contradict some of the predictions of the fuzzy-trace th eory. Conclusions. Most patients failed to understand the risks and benefit s associated with CEA. Some patients' estimates of stroke risk were actuall y greater than the perceived potential benefit of surgery in terms of risk reduction. The data also suggested a positive correlation between the degre e of perceived benefit and the degree of perceived risk.