The long-term effects of psychotherapy on borderline personality disorder

Data on psychiatric hospitalisation were collected by interviewing patients at two monthly intervals using the Client Service Receipt Inventory, which was then triangulated with data from electronic patient records. In the year prior to treatment, 24 patients had been hospitalised with the number of inpatient days ranging from 0 to 365 (mean 20.5, SD 63.1).

The number of inpatient days in the year prior to treatment did not differ between conditions. During the 12-month intervention period, 2 patients allocated to DBT and 11 allocated to TAU were hospitalised. For the 2 patients hospitalised in the DBT condition, 1 was hospitalised following dropping out of DBT, whilst the other was a long-term inpatient when beginning DBT, and remained so for the first 3 months of treatment.

A logistic regression showed that the odds of hospitalisation during the intervention period were significantly higher in patients allocated to the TAU condition. This difference remained significant after adjusting for whether patients had been hospitalised in the year prior to treatment.

A standardised self-harm interview was also used to assess self-harm frequency during the follow-up period. The mean number of days with self-harm in the last 2 months of treatment for DBT completers was 1.79 (SD 3.68) whilst the mean number of days with self-harm during the 6 months after treatment was 1 (SD 1.80), i.e. a rate of 0.33 days per 2-month period. A Wilcoxon signed-rank test showed that this was not a significant difference (z = 1.42, p = 0.16). No DBT completers had any inpatient hospitalisations during the 6-month follow-up period. For treatment dropouts, the rate of follow-up was too low (8 of 21 participants) to render statistical comparison valid.

These findings on hospitalisation concur with international RCTs that have shown DBT can reduce hospitalisation, but are in contrast with another UK RCT which found hospitalisation days did not differ between DBT and TAU. Treatments which reduce the use of inpatient resources are particularly important, given that patients with BPD have been found in several studies to make greater use of inpatient psychiatric services than patients with major depressive disorder or other personality disorders.

The high healthcare costs (and presumably patient distress) resulting from such frequent hospitalisation render the implementation of interventions that can reduce hospitalisation an important priority for this patient group. Thus, DBT should be considered an effective intervention for keeping self-harming patients with BPD out of hospital, and that positive effects on self-harm and hospitalisation are sustained once treatment is over.