title: A cross-sectional population-based study on the association of personality traits with anxiety and psychological stress: Joint modeling of mixed outcomes using shared random effects approach.
abstract: BACKGROUND
  Previous studies have showed some evidences about the relationship between personality traits particularly neuroticism and extroversion, separately, with psychological stress and anxiety. In the current study, we clarified the magnitude of joint interdependence (co-morbidity) of anxiety (continuous) and Psychological stress (dichotomous) as dependent variables of mixed type with five-factor personality traits as independent variables.
  
  
  METHODS
  Data from 3180 participants who attended in the cross-sectional population-based "study on the epidemiology of psychological, alimentary health and nutrition" and completed self-administered questionnaires about demographic and life style, gastrointestinal disorders, personality traits, perceived intensity of stress, social support, and psychological outcome was analyzed using shared random effect approach in R Free software.
  
  
  RESULTS
  The results indicated high scores of neuroticism increase the chance of high psychological stress (odds ratio [OR] = 5.1; P < 0.001) and anxiety score (B = 1.73; P < 0.001) after adjustment for the probable confounders. In contrast, those who had higher scores of extraversion and conscientiousness experienced lower levels of anxiety score (B = -0.54 and -0.23, respectively, P < 0.001) and psychological stress (OR = 0.36 and 0.65, respectively, P < 0.001). Furthermore, higher score of agreeableness had significant negative relationship with anxiety (B = -0.32, P < 0.001).
  
  
  CONCLUSIONS
  The present study indicated that the scores of neuroticism, extraversion, agreeableness and conscientiousness strongly predict both anxiety and psychological stress in Iranian adult population. Due to likely mechanism of genetic and environmental factors on the relationships between personality traits and psychological disorders, it is suggested to perform longitudinal studies focusing on both genetic and environmental factors in Iranian population.
authors.affiliation: Department of Biostatistics and Epidemiology, School of Health, Isfahan, Iran ; Psychosomatic Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Awat
authors.initials: A
authors.lastname: Feizi
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Ammar Hassanzadeh
authors.initials: AH
authors.lastname: Keshteli
authors.affiliation: Department of Biostatistics and Epidemiology, School of Health, Isfahan, Iran ; Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Nouri
authors.affiliation: Psychosomatic Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Roohafza
authors.affiliation: Department of Internal Medicine, School of Medicine and Integrative Functional Gastroenterology Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Peyman
authors.initials: P
authors.lastname: Adibi
keywords: Anxiety; mixed outcomes; personality traits; psychological stress; shared random effect model