The validity of informed consent in a clinical study.

Patients, aged 36 to 78 years, who had participated in two studies that included the ventilatory effects of postoperative analgesia, returned a questionnaire canvassing their views of the procedure for obtaining consent and the conduct of the study. Fourteen of 18 patients from one study, and all 18 from the second, returned their questionnaires. Thirty of the 32 patients were satisfied with the pre-operative explanation. Eleven patients felt obliged to take part, not because of coercion, but from a sense of duty to others. The breathing tests caused discomfort to eight patients but only one of them found this more than expected from the pre-operative explanation. Only two patients, both in the second study, said that they would not volunteer again for a similar study. There was no suggestion that the age of the patient or the fact that they were undergoing major surgery had any influence on their attitudes or comprehension. It may be prudent to use this type of questionnaire to evaluate the response of patients to some research projects.