Intervention intensity

Few studies have examined brief interventions for personality disorder, presumably because of the chronic course of disorder, a complex symptomatology and guidelines that caution against low-intensity treatment. The present findings suggest that short-term MBT, delivered routinely as an initial introductory intervention within a stepped-care DTC model of service, is associated with positively directed self-reported symptom and functional change in people with personality disorder. Thus, in the context of the OCNS service evaluated here, short-term MBT appears to be a useful initial strategy for expanding treatment access for people with personality disorder before more intensive extended care.

There have been few service evaluation studies examining treatments for personality disorder. Previous work examining brief psychological treatments for personality disorder has focused on service-based outcomes such as reduced treatment cost and decreased hospital utilisation.^{Reference Meuldijk, McCarthy, Bourke and Grenyer23,Reference Grenyer, Lewis, Fanaian and Kotze24} Huxley et al recently presented service evaluation data showing that brief psychological treatment is also associated with improvements in clinical outcomes such as borderline symptoms, suicidal ideation and quality of life.^{Reference Huxley, Lewis, Coates, Borg, Miller and Townsend25} The current study is the first to conduct a service evaluation on the use of short-term MBT applied as a routine part of care in the OCNS. There is a lack of similar service evaluation studies examining pre–post changes in mental health and psychosocial outcomes over time in people receiving short-term MBT intervention. Most work in this area has instead looked at longer duration treatment, often specifically for BPD.

Evidence-based studies examining MBT have done so for BPD, and involve long-term treatment durations (over 12 months).^{Reference Vogt and Norman10} In-patient MBT studies as short as 4-weeks have reported beneficial outcomes from treatment,^{Reference Brüne, Dimaggio and Edel26,Reference Edel, Raaff, Dimaggio, Buchheim and Brüne27} but findings from these studies cannot be extrapolated easily to out-patient settings because of the differences in intensity of care and use of a combination of other therapies, such as dialectical behaviour therapy (DBT). RCT studies of brief psychological interventions for personality disorder have been conducted primarily among people with BPD. A recent meta-analytic review of this literature also shows a predominance of short-form DBT or therapies that include substantial DBT-inspired components.^{Reference Spong, Clare, Galante, Crawford and Jones28} However, no studies examining short-term MBT exclusively were identified.

Few RCTs exist examining the efficacy of other therapies applied as brief interventions for groups with BPD and mixed personality disorders. Korrelboom et al examined a 7-week adjunctive Competitive Memory Training (COMET) programme compared with treatment as usual in a group of mixed personality disorder diagnoses,^{Reference Korrelboom, Marissen and van Assendelft29} Blum et al examined a 20-week adjunctive Systems Training for Emotional Predictability and Problem Solving (STEPPS) treatment compared with treatment as usual in BPD,^{Reference Blum, John, Pfohl, Stuart, McCormick and Allen30} and most recently, Crawford et al examined a six-to-ten session structured psychological support (SPS) programme compared with treatment as usual in a mixed cohort of people with personality disorder.^{Reference Crawford, Thana, Parker, Turner, Carney and McMurran31} SPS draws on techniques used in MBT and therefore, out of the RCT work highlighted above, might be considered the closest to the MBT intervention evaluated in the OCNS in terms of therapeutic focus and treatment duration. Innovative brief interventions investigated in the aforementioned RCT studies have demonstrated improvements in specific symptom outcomes, social functioning and patient well-being. Thus, the post-MBT changes that we describe in this service evaluation are clinically intuitive and correspond with trial data that examine the efficacy of treatment.

However, as this was a non-randomised and uncontrolled study, we cannot determine that improvement of outcomes pre–post intervention was as a result of treatment benefit per se. Replication with a matched control group is necessary to confirm an efficacy signal compared with waiting list or active control treatment. Meta-analysis of BPD studies suggests that treatment effect sizes are greater for brief interventions delivered adjunctively and smaller when compared withmanualised control interventions.^{Reference Spong, Clare, Galante, Crawford and Jones28} Thus, treatment efficacy of intervention beyond that of structured contact is presently unclear, and is an additional consideration for future trials examining short-term MBT. The duration of the programme assessed here is also similar to that of the mean intervention length of brief intervention studies identified by review.^{Reference Spong, Clare, Galante, Crawford and Jones28} Future clinical trials that compare short-term with longer-term MBT are required to clarify the optimal length of brief interventions in personality disorder. Juul et al proposed an RCT to examine this point in BPD.^{Reference Juul, Lunn, Poulsen, Sørensen, Salimi and Jakobsen32} Future work targeting a mixed cohort of people with personality disorder is also required to confirm the present findings suggesting symptom improvement at post-intervention.

Treatment outcomes

Improved symptom outcomes reflected domains of emotional dysregulation (emotional reactivity), interpersonal dysfunction (social functioning) and mixed psychiatric symptom distress (e.g. depressed mood, disturbed sleep and difficulty concentrating). Our results agree with findings indicating psychological treatment benefits for personality disorder. Psychotherapy reduces mood instability,^{Reference Storebø, Stoffers-Winterling, Völlm, Kongerslev, Mattivi and Jørgensen11} and several studies demonstrate that MBT associates specifically with improved social functioning.^{Reference Vogt and Norman10,Reference Storebø, Stoffers-Winterling, Völlm, Kongerslev, Mattivi and Jørgensen11}

Pre- to post-treatment effect sizes in this study were predominantly of medium strength, and small for social functioning. Similarly designed cohort studies (i.e. those using within-group comparisons) for MBT-based interventions have reported larger treatment effects;^{Reference Bales, Timman, Andrea, Busschbach, Verheul and Kamphuis33,Reference Laurenssen, Hutsebaut, Feenstra, Bales, Noom and Busschbach34} however, this may be because treatment duration was also substantially longer. In the context of a whole service model of stepped-care, MBT, as delivered here, is not intended to be a complete course of treatment. Further treatment gains are likely achievable with extended care.

A frequent limitation of studies examining MBT is that parallel measurement of mentalising change is not generally assessed. Consequently, little is known about the actual therapeutic mechanisms of treatment.^{Reference Vogt and Norman10} Assessment of mentalising improvement was an explicit outcome in evaluating this service.

Expectedly, mentalising capacity improved from baseline assessment to post-MBT assessment. Furthermore, improvements in mentalising capacity predicted improvements in emotional reactivity and social functioning. That mentalising was associated with improvements on these domains is consistent with the conceptual basis for intervention. Mentalising involves developing reflective insight into one's own mood state, and forms an important part of social cognition in the context of perceiving and understanding the motivations and perspectives of others.

It is hypothesised that social and cognitive difficulties moderated by reduced mentalisation underpin the severe emotional dysregulation and interpersonal dysfunction that are core symptoms of BPD. MBT has also been suggested as a viable treatment approach for other Cluster B personality disorders, where disturbances are characterised primarily by emotional dysregulation.^{Reference Luyten, Campbell, Allison and Fonagy12,Reference Drozek and Unruh35} Concordant with our service user outcomes, mentalising improvements are associated with reduced interpersonal distress.^{Reference Hayden, Müllauer, Gaugeler, Senft and Andreas36} Emotional dysregulation and interpersonal dysfunction are primary reasons for people with personality disorder to seek treatment. Consequently, establishing which therapies are effective at targeting these symptom domains in future RCT studies is important for developing appropriate short-term treatments where service users derive maximum benefit.

It is unclear why we did not detect an association between mentalising capacity and general psychiatric symptom distress captured by the GHQ-12, despite significant improvement on this outcome. The diverse and non-specific symptom characteristics captured by the instrument may lack a clear symptom adjacency to mentalisation to show a proportionate association. Improvement on this outcome may not arise from mentalising capacity per se, but because of improved psychosocial functioning following improvement on proximal domains such as emotional reactivity and social functioning, as described above. Indeed, previous studies involving people with personality disorder have shown close associations between mood instability and other psychiatric symptoms, such as sleep disturbance^{Reference McGowan, Goodwin, Bilderbeck and Saunders37} and impaired neurocognitive performance.^{Reference Schulze, Domes, Krüger, Berger, Fleischer and Prehn38} Improvements on this measure may have been also moderated by the DTC components of the intervention: communal experience and democratisation of group member roles are plausible contributors to improvement in self-reported psychosocial functioning (reflected partially through GHQ-12 and the aforementioned SFQ scores).

Satisfaction with care improved from baseline to post-treatment assessment, and showed the largest improvement of all outcomes assessed. Poor experience of care in mental health settings is an important factor influencing engagement with treatment and premature withdrawal from care.^{Reference Mitchell and Selmes39} Furthermore, this can be additionally challenging for personality disorder services because people with personality disorder tend to express lower satisfaction with care, possibly resulting from unfulfilled expectations about symptom improvement.^{Reference Priebe and Miglietta40} In the context of the service evaluated, satisfaction with short-term intervention is an important outcome that may have implications for service user engagement and retention at OCNS. We highlight that within a whole model of treatment for personality disorder, positive introductory experience with psychotherapy is likely to play an important role in maintaining engagement with follow-on extended care. As above, the democratised and communal nature of therapy delivered via a DTC model may account for improvement rather than mentalising improvement, which did not predict client satisfaction. Shared sense of endeavour among service users as well as group facilitation by practitioners that were experienced personality disorder clinicians may also have affected client satisfaction with care. However, without empirical confirmation of the above in this service, these are presently only speculative possibilities. Future qualitative methods may aid the identification of which group member and therapist experiences contribute to pre–post self-reported change.

Strengths and limitations

To our knowledge, this is the first service evaluation study examining short-term MBT for personality disorders. Few service evaluation studies examine pre–post intervention changes in mental health and psychosocial functioning. In the context of an introductory psychotherapy programme offered to service users at the OCNS, short-term MBT appears to achieve favourable self-reported outcomes compared with when people are assessed at the beginning of treatment. Thus, short-term MBT offered through the OCNS might be a helpful first-step treatment for people with personality disorder who are referred to the service. A strength of this evaluation was the inclusion of the MZQ measure of mentalising capacity; seldom have empirical studies (including RCTs) used a parallel measure of mentalising function. That mentalising capacity was improved, and that improvement was associated with positive change on other outcomes further suggests that short-term MBT fulfils its purpose as an initial treatment targeting mentalising difficulties for people attending the OCNS.

This work has several limitations. First, we lack the experimental control necessary to evaluate the efficacy of short-term MBT in a placebo-controlled manner. Thus, we cannot infer that the pre–post improvements in mental health and psychological functioning are necessarily because of the intervention or the individual therapeutic components of MBT, and could reflect regression to the mean. Treatment fidelity was also not assessed by external observation, as might be done in an RCT study. Furthermore, as a service evaluation, the purpose of this study was to examine the intervention in the context of the service in which it was provided, and therefore data collection was not intended to produce findings generalisable beyond the OCNS service. Second, as data collection was naturalistic, it also lacked the systematic approach that would be present in a cohort study with a clearly pre-defined design and a priori hypotheses. Data were available from people who completed the intervention and who returned self-reported assessments only, and therefore we were unable to assess loss to follow-up. Third, because of partial responses on self-reported outcome measures, we cannot exclude the possibility of response bias among participants. However, supplementary analyses determined that only CSQ-8 non-respondents showed any significant differences to questionnaire respondents, and this was unlikely to indicate positive response bias as CSQ-8 non-responders showed greater improvement. Future RCTs with an intention-to-treat design are needed to examine the efficacy of short-term out-patient MBT for personality disorder. As suggested recently by a contemporary meta-analysis of the BPD brief intervention literature,^{Reference Spong, Clare, Galante, Crawford and Jones28} demonstrating treatment superiority of intervention above regular structured contact between clients and the service is also needed to corroborate the promising findings described here. Finally, the outcome measures collected by the service did not probe individual symptoms of personality disorder because of the diverse representation of diagnoses in the service that involve heterogenous core symptoms. Future studies incorporating measures of core symptom severity are required to disentangle whether complex individual symptoms (e.g. fears of abandonment, suicidality, impulsivity) are more or less sensitive to treatment, and to determine core symptom severity at the start of treatment.

In conclusion, we found that a short-term (10-week) out-patient MBT treatment programme for personality disorder was associated with significant pre–post changes in self-reported outcomes reflecting mental health, psychological functioning and satisfaction with care among service users. The short-term MBT intervention deployed at the OCNS may increase the availability of appropriate care for personality disorder and improve treatment access where, traditionally, long waiting lists result in delayed treatment and substantial exclusion from care. In this service, brief intervention is not considered a substitute for long-term treatment of personality disorder, but rather may be used within a stepped-care model of service to prioritise access to suitable psychological therapies and introduce service users to intervention.