Who volunteers for phase I clinical trials? Influences of anxiety, social anxiety and depressive symptoms on self-selection and the reporting of adverse events

Objective To investigate the influence of anxiety, social anxiety and depressive symptoms on the willingness of healthy subjects to volunteer for phase I studies and to report adverse events. Materials and methods A group of healthy subjects who had never participated in a clinical trial ("Naive Subjects") were invited to participate in a phase I study. All subjects were assessed for trait anxiety ( State- Trait Anxiety Inventory, STAI-T), social anxiety ( Social Avoidance and Distress, SAD, and Fear of Negative Evaluation, FNE) and depressive symptomatology ( Beck Depression Inventory, BDI- II). Subjects who accepted the invitation to participate were compared with those who refused. The personality traits of a group of " Actual Participants" were examined, and the relation of these traits to adverse events reported during participation was evaluated. Results A significant inverse correlation was found between the STAI- T ( R=- 0.203, p< 0.05) and SAD ( R=- 0.204, p< 0.05) scores and the willingness to participate. Naive Subjects who refused the invitation to participate showed higher scores on STAI- T ( Z=- 2.600, p< 0.01) and SAD ( Z=- 2.524, p< 0.05) inventories. Logistic regression using BDI- II, STAI- T, SAD and FNE as covariates also showed that the only unique predictors of participation were the STAI- T ( p< 0.05) and SAD ( p< 0.01) scores. Significant positive correlations were found between trait anxiety and reporting of adverse events. Conclusion Participants in phase I studies are a self-selected sample defined by low trait- anxiety and social avoidance behaviors. This self- selection bias may affect the study results because less anxious subjects tend to report fewer adverse events. The characterization of a participant's personality traits may be important in phase I studies.