Depression predicts disability in long-term chronic pain patients

Purpose : Investigators have examined factors that predict treatment outcome and disability status in chronic pain patients, including psychopathology and personality characteristics with equivocal results. The purpose of this study was to evaluate the usefulness of personality characteristics, depression, and personality disorders in predicting disability status in pain patients with long-term follow-up. The setting was a rehabilitation hospital in Southern Sweden. Method : Subjects were 184 pain patients (mean age=43.4 (10.8) years; 72.8% female) who had no more than 365 sick leave days (Mean sick leave days=132.7 (128.2)) prior to the baseline personality and psychiatric evaluation. The baseline evaluation consisted of a psychiatric interview that included the administration of the Structured Clinical Interview for DSM-IV Screen Questionnaire (SCID-II), the Montgomery-Åsberg Depression Rating Scale (MADRS), and the Karolinska Scales of Personality (KSP). Disability status was assessed by insurance record review a minimum of two-and-a-half years after baseline evaluation. Results : Multivariate logistic regression suggests that age (OR=1.09, 95% CI=1.02-1.18; p =0.013), number of sick leave days prior to evaluation (OR=1.01, 95% CI=1.01-1.02; p =0.018), and baseline diagnosis of depression significantly predicted subsequent disability status (OR=7.04, 95% CI=1.15-42.93; p =0.034). Baseline personality traits and the diagnosis of a personality disorder were not useful predictors of disability status in our sample. Conclusions : These data suggest that depression, but not personality disorders characteristics, was an important disability predictor in chronic pain patients with extended follow-up.