Background. Borderline personality disorder (BPD) is a serious mental illness. Due to scepticism about the effectiveness of its treatment, the care of these patients is neglected. In this study we evaluated the effect of treatment 5 years after its ending, of patients with BPD.

Method. Thirty subjects were treated twice weekly for 1 year by psychotherapy based on the ‘Conversational Model’ of Hobson. Outcome measures included time in hospital, number of episodes of violence and self-harm, number of medical appointments, drug use and work history. A ‘morbidity budget’ made up of these items was collated for the year before treatment, the year following treatment, and for the year preceding the 5-year follow-up. Additional measures included DSM-III criteria and a self-report of symptoms. These outcomes were compared to a hypothetical natural history of BPD constructed from the DSM scores of 150 borderline patients aged between 18 and 52 years.

Results. Except for one measure, the improvements evident 1 year following treatment were maintained 4 years later. This improvement was not predicted by the hypothetical natural history.

Conclusion. A particular form of treatment of BPD has relatively long-lasting, beneficial effects.