OBJECTIVES: To investigate the knowledge about randomized clinical trials and the attitude towards clinical research among Danish outpatients and to examine the relationships between outpatient demographic variables and knowledge and attitude.

SETTING: Outpatients (n = 415) were recruited from four departments at a university hospital in Copenhagen.

METHODS: The participants answered an 18 item multiple choice test evaluating knowledge about randomized clinical trials and a 32 item Likert format questionnaire evaluating attitudes towards clinical research in general and randomized clinical trials. Assessment of scales for knowledge and attitudes was performed using Rasch analysis and Cronbach's alpha. Associations between demographic variables, knowledge score and attitude score were examined using analysis of variance.

RESULTS: Mean age for all outpatients was 46 years (range 18-88 years); 251 (60%) were females. A total of 27 outpatients (7%) had previously participated in a randomized clinical trial. Mean knowledge score (number of correct answers out of a maximum of 17) was 7.9 (SD 3.1). Patients in the younger age groups and patients with longer education had significantly higher knowledge scores (p < 0.001). The effect of age group (estimated increase in knowledge score relative to the group 60-89 years) was: 18-29 years 1.2 (SE 0.4); 30-39 years 2.0 (SE 0.4); and 40-59 years 1.6 (SE 0.4). The effect of education (estimated decrease in knowledge score relative to patients with > 12 years of education) was: < 7 years 3.4 (SE 0.4); and 8-11 years 2.0 (SE 0.3). Mean total attitude score was 74.8 (SD 14.8) on a scale from 0-128. Compared to female patients, male patients had an estimated 5.1 points (SE 1.5) higher attitude score (p < 0.001). There was a weak but significant positive association (r = 0.38; p < 0.001) between the knowledge score and the total attitude score.

CONCLUSION: Among Danish outpatients knowledge about randomized clinical trials is better in the younger age groups and in individuals with longer education. Overall, better knowledge was associated with a more positive attitude towards clinical research. The question is whether it is possible by simple means to increase knowledge about clinical research and whether an increase in knowledge may positively affect the attitude towards clinical research in individual patients.