A high prevalence of Self-Injurious Behaviour (SIB) and suicide attempts has been found in patients with Eating Disorders (ED) as well as in patients with a Borderline Personality Disorder (BPD). Since there is a high comorbidity of these two disorders the impact of BPD on the occurrence of self-harm in patients with ED is unclear. This study examined the occurrence and clinical relevance of SIB and suicide attempts in a large sample of 1638 female inpatients with ED, comparing patients with and without a comorbid BPD.

The sample consists of 632 patients with anorexia, 659 with bulimia nervosa and 347 with EDNOS according DSM-IV; 100 had a comorbid BPD. The assessment included the Eating Disorder Questionnaire, the Eating Disorder Inventory, the Self-Harm Behaviour Survey, the Traumatic Life Event Questionnaire, the Dissociative Experience Scale, the Barratt Impulsivity Scale and other.

The lifetime prevalence for the whole sample of SIB and for suicide attempts was 34% and 33% respectively. The risk for SIB doubled with the presence of a comorbid BPD and the risk for suicide attempts increased fivefold. The presence of BPD was associated with significantly severer psychopathology but neither SID nor BPD did compromise the treatment outcome.

SIB and suicidal behaviour are common and important issues in patients with eating disorders. A comorbid BPD increases the risk of SIB and especially of suicide attempts dramatically. This should be taken into account in primary care in order to identify this high risk group.