Impact on suicidality of the borderline personality traits impulsivity and affective instability.

BACKGROUND: The aim of this study was to test the impact on suicidality (suicide threats, attempts) of the borderline personality disorder (BPD) traits impulsivity and affective instability in mood disorders.

METHODS: In a general psychiatry private practice (nontertiary care), consecutive remitted, non-substance-abusing outpatients--138 with bipolar II disorder (BP II) and 71 with major depressive disorder (MDD)--self-assessed using the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) Questionnaire.

RESULTS: The frequency (higher in BP II) of suicidality was 14%; impulsivity, 37%; and affective instability, 58%. The suicidality-positive patients (n = 30), when compared with the suicidality-negative patients (n = 179), had more BP II, more impulsivity (odds ratio [OR], 5.5; 95% confidence interval [CI], 2.3 to 13.3), and more affective instability (OR, 2.4; 95% CI, 0.99 to 6.0). Logistic regression of suicidality vs impulsivity and affective instability (controlled for BP II; age; and interactions among BP II, age, impulsivity, and affective instability), showed that impulsivity was a strong independent predictor of suicidality (OR, 4.3; 95% CI, 1.7 to 10.6), and that affective instability was not an independent predictor of suicidality (OR,1.6; 95% 0.6 to 4.1). BP II showed neither confounding nor interactions.

CONCLUSION: Results showed a strong independent impact of impulsivity-but not affective instability-on suicidality in BPD. No confounding by mood and substance disorders supported the BPD nature of these associations.