Previous investigators have studied the connection between hypothesized personality types and specific forms of disease (e.g. Type A personality and cardio vascular disease), but evidence regarding personality in medical regimen compliance is sparse. Important questions exist about the utility of using categorical models of personality psychopathology (i.e.: the DSMIV personality disorder diagnostic criteria) vs. dimensional models of personality (i.e.: Costa and McCrae's Five Factor Model), as well as how depression influences personality's relationship with compliance. Furthermore, self-reports and informant-reports provide very different perspectives on personality, with correlations between these sources ranging from 0.20 to 0.35.

The current study had two primary objectives: (a) demonstrate personality's relationship with compliance in hemodialysis patients, and (b) determine which source of personality (family member/friend or social worker) information was better able to predict compliance. Self-reported personality data were collected for 162 hemodialysis patients; informant-report personality data were collected for 147 patients. Self-report and informant-report correlations were lower than reported in some past research, and ranged between 0.03 to 0.24. Five self-reported DSM-IV personality disorders (PDs), Borderline, Dependent, Histrionic, Narcissistic, and Paranoid were associated with total number of minutes missed in the past year (r's ranging from 0.21-0.26, p's < 0.05). Informant-report OCPD was the only PD associated with total number of minutes missed in the past year (r = -.22, p < .05). NEO factors were not significantly correlated with compliance.

The results of informants varied based on the informant sources. Social worker-report of PDs had the strongest associations with total number of minutes missed from treatment (Antisocial, Borderline, Histrionic, Narcissistic, Paranoid, & Schizoid; r's ranging from 0.29-0.45, p's < 0.05). Significant changes in no-show behavior and total number of minutes missed in the past year were accounted for by the 10 DSM PDs, controlling for depression, (F(11, 35) = 2.48 and 3.09, p's = 0.03 & 0.01, respectively). The connection between personality and compliance is an important research issue for psychology and an important issue in the practice of medicine; it has implications for interventions targeted at modifying adherence behaviors among chronically ill patients.