Personality characteristics of volunteers in Phase 1 studies and likelihood of reporting adverse events

Int J Clin Pharmacol Ther. 2008 Jul;46(7):340-8. doi: 10.5414/cpp46340.


Objective: To evaluate the personality characteristics of a group of participants in Phase 1 studies and to study the relation between the personality traits and the adverse events during participation.

Methods: Study population consisted of 139 healthy volunteers to Phase 1 studies. Personality was assessed through the Revised NEO Personality Inventory (NEO-PI-R) and adverse events were monitored during participation.

Results: Participants showed lower levels of Neuroticism (p < 0.001), and higher levels of Extraversion (p < 0.001) and Openness to Experience (p < 0.001) than the norm. In the Neuroticism domain, participants were lower in anxiety (p < 0.001), angry-hostility (p < 0.001), depression (p < 0.001), self-consciousness (p < 0.001) and vulnerability (p < 0.001), and higher in impulsiveness (p < 0.001). All facets of the Extraversion domain and all facets but "openness to esthetics" of the Openness to Experience domain were higher (p < 0.001) in the participants in relation to the norm. Participants were significantly lower (p < 0.05) on the overall Agreeableness domain, however, they were remarkably higher in altruism (p < 0.001) and trust (p = 0.001). Participants did not differ from the norm in the overall Conscientiousness domain, but they scored higher in competence (p < 0.001), achievement striving (p = 0.001) and self-discipline (p < 0.001). Females showed to report significantly more adverse events than males, and extraverted subjects showed to report less adverse events than introverted subjects.

Conclusion: Participants who volunteer for Phase 1 studies, differ from the general population in their personality characteristics. Some personality characteristics may have an effect on the probability of reporting adverse events during participation. Therefore, defining a personality of a volunteer may assume significant importance in Phase 1 studies.

MeSH terms

  • Adolescent
  • Adult
  • Adverse Drug Reaction Reporting Systems*
  • Clinical Trials, Phase I as Topic / methods
  • Clinical Trials, Phase I as Topic / psychology*
  • Drug-Related Side Effects and Adverse Reactions
  • Female
  • Humans
  • Likelihood Functions
  • Male
  • Patient Selection*
  • Personality Inventory
  • Personality*
  • Sex Factors