- Top of page
- Significant outcomes
- Material and methods
- Declaration of interest
Objective: This study presents data from a randomized outcome study comparing mentalization-based and supportive psychotherapy for patients with borderline personality disorder (BPD).
Method: Eighty-five SCID-II diagnosed borderline patients were randomized to either i) 2 years of intensive (twice weekly) combined (individual and group), mentalization-based psychotherapy (MBT) or ii) 2 years of less-intensive (biweekly) supportive group therapy. Treatment outcome was assessed using a battery of self-report questionnaires, SCID-II interviews and therapist-rated global assessment of functioning (GAF).
Results: Fifty-eight patients completed 2 years of treatment. Significant changes in both treatment groups were identified for several outcome measures, including self-reported measures of general functioning, depression, social functioning and number of diagnostic criteria met for BPD, as outlined by the SCID-II interview. General linear modelling was used to compare treatment outcome in the two groups. Only GAF showed a significantly higher outcome in the MBT group. A trend was found for a higher rate of recovery from BPD in the MBT group. Pre-post effect sizes were high (0.5–2.1) and for the most part highly significant in both groups.
Conclusion: The study indicates that both MBT and supportive treatment are highly effective in treating BPD when conducted by a well-trained and experienced psychodynamic staff in a well-organized clinic.
- Top of page
- Significant outcomes
- Material and methods
- Declaration of interest
Borderline personality disorder (BPD) represents a substantial health problem, particularly among women. It is marked by chronic instability, identity disturbance, severe subjective distress, self-destructive behaviour and low levels of functioning in a broad range of areas, including dysfunctional relationships, unemployment, continuous dependency on welfare systems, poverty and general underachievement in terms of education, work, etc. (1). Psychosocial functioning and particularly vocational functioning is often substantially compromised in BPD patients (2). The prevalence of BPD is estimated at approximately 1–1.5% in the general population and up to 20% among psychiatric in-patients (3, 4). Comorbidity with other personality disorders, severe symptom disorders (depression, bipolar disorder, PTSD and anxiety disorders), alcohol/drug abuse and behavioural disorders (eating disorders, self-destructive behaviour) is substantial (5), and the lifetime risk of suicide is estimated to be up to 10% (5).
Historically, BPD has been viewed as a disorder, which is notoriously difficult to treat, evidenced by high levels of patient drop-out during therapeutic interventions, etc. (6, 7). In the last 10–15 years, a number of studies have supported the efficacy of different forms of specialized long-term psychotherapy. Based on these studies, BPD patients appear to recover more rapidly (and in part more spontaneously) than previously anticipated on most symptomatic dimensions, except general levels of adaptive functioning (social and occupational) (8). There is a growing consensus that intensive, focused and highly structured long-term psychotherapy is the most suitable treatment for severely disturbed BPD patients. However, no single treatment model has been established as the primary treatment of choice. Some empirical support has been found for at least four comprehensive treatment models: transference-focused psychotherapy (TFP) (9, 10), dialectical behaviour therapy (DBT) (11), mentalization-based treatment (MBT) (12) and schema-focused therapy (SFT) (13). In addition to this, Systems Training for Emotional Predictability and Problem Solving (STEPPS), a 20-week group-based program for BPD out-patients, has gained some empirical support (13–16).
At present, there is minimal empirical evidence to indicate which of the four comprehensive treatment models is most effective. Our knowledge concerning the effectiveness of the four treatment models in clinical practice (outside their respective centres of development) is still limited and therefore further studies are needed. Bateman and Fonagy (17) noted that when treatments are evaluated by the researchers who designed and developed them, there is a risk of bias (allegiance). Consequently, replication by independent groups is urgently required.
To date, eight randomized outcome studies have been conducted outside the sites of the development of the respective BPD treatment models. Koons et al. (18) and Verheul et al. (19) compared DBT (6 and 12 months respectively) with treatment as usual. Carter et al. (20) compared 6 months DBT with TAU and waiting list. All three studies found that DBT was superior to TAU on some but not all outcome measures. McMain et al. (21) compared 1-year DBT with a manualized version of general psychiatric management as described in the APA practice guidelines for BPD treatment (22). They found no significant differences between the two groups. Similarly, Feigenbaum et al. (23) found practically no significant differences in outcome between 1year of DBT and TAU. In a comparison of the effectiveness of 3 years of TFP and SFT, Giesen-Bloo et al. (24) found that significantly more patients in SFT recovered or showed reliable clinical improvement on a BPD severity index compared with patients in TFP. However, this study has been criticized for insufficient integrity checks (indicating inadequate therapist adherence) of the delivered TFP treatment (25). Pribe et al. (26) studied the effectiveness of DBT in a randomized controlled design. Finally, in a comparison of 1-year TFP with psychotherapy in the community, Doering et al. (27) found that TFP was superior on selected outcome measures like BPD symptomatology, psychosocial functioning and personality organization. Overall, the results indicate that intensive therapeutic interventions are more effective than treatment as usual for patients with BPD (18–20); however, the question of whether any one therapeutic intervention model provides greater clinical advantage to BPD patients than the other intervention models remains unclear. Furthermore, one of the four comprehensive treatments models outlined earlier, mentalization-based therapy, has not yet been the subject of a randomized outcome study outside the centre in which it was developed. Therefore, a randomized outcome study investigating the efficacy of mentalization-based therapy for BPD is required.
One important issue when conducting empirical investigations of psychological therapies for BPD is the ability to keep BPD patients in treatment. The Doering et al. (27) and Verheul et al. (19) studies experienced significantly lower drop-out rates from the experimental treatment (DBT and TFP respectively) compared with TAU. Conversely, Feigenbaum et al. (23) experienced significantly higher drop-out from the experimental treatment (DBT) compared with TAU.
The present study is the first randomized trial of MBT that has not been conducted by its developers. Moreover, only one randomized study to date has looked at the outcome of long-term (psychodynamic) supportive therapy in borderline patients. Clarkin et al. (28) found that 1 year of TFP, DBT and supportive treatment was generally equivalent with respect to broad positive change in borderline patients.
Aims of the study
The aim of the study was to investigate and compare the outcome of 2 years of mentalization-based psychotherapy and 2 years of supportive group therapy in patients with borderline personality disorder (BPD).
- Top of page
- Significant outcomes
- Material and methods
- Declaration of interest
85 (58 + 27) patients started treatment. The remaining 26 patients never started treatment or refused to participate in the study after randomization. As a result, there was an overall drop-out rate of 43% (48 of 111) from the intention to treat group. 58 patients completed 2 years of treatment. 22 patients dropped out of treatment and five patients (‘quick responders’) terminated the course after <2 years (after 8, 18, 19, 21 and 22 months) because they did not have a need for further treatment. Reasons for drop-out are listed in Fig. 1. Four patients were re-diagnosed as non-BPD and referred to other clinics that specialized in the respective disorders; symptoms that were interpreted as signs of BDP at the time of assessment were retrospectively re-interpreted as signs of other disorders when the therapists learned more about the patients (one schizophrenia, one schizotypal disorder, one chronic depression and one Asperger’s syndrome). These patients remained part of the sample until the time of their re-diagnosis when the collection of data was stopped. Sixteen of the 58 patients starting combined treatment terminated prematurely (excluding the quick responders), meaning that there was a drop-out rate of 28% for patients starting in this treatment. The drop-out rate in the group of patients starting supportive group therapy was 22%. The level of attrition from the two groups was not significantly different (Fisher’s exact test, P = 0.79).
Essential demographic and clinical characteristics at intake are reported in Table 1. In the group of patients allocated to MBT treatment, 53 (72%) met diagnostic criteria for depression (nine in remission at the time of assessment), 27 (37%) met criteria for anxiety disorder, 14 (19%) met criteria for an obsessive–compulsive disorder and 36 (49%) for a (previous or current) eating disorder. On Axis II, 48 (65%) met criteria for at least one personality disorder other than borderline, 16 (22%) for avoidant PD. In the supportive therapy group, 28 (76%) met criteria for depression (eleven of these were in remission at assessment), 9 (24%) met criteria for anxiety disorder, 5 (14%) for an obsessive–compulsive disorder and 14 (38%) for an (past or current) eating disorder. 32 (86%) met criteria for at least one other personality disorder, 10 (27%) for avoidant PD. None of the differences in comorbidity between the randomized groups were significant (Fisher’s exact test, P > 0.3).
Table 1. Demographic and clinical characteristics at intake of patients with borderline personality disorder (BPD) (n = 111) and patients starting combined mentalization-based treatment (MBT) (n = 58) or supportive group treatment (n = 27)
| ||Combined MBT Mean/N (SD/%) (n = 74)||Supportive group Mean/N (SD/%) (n = 37)||Starting MBT Mean/N (SD/%) (n = 58)||Starting supportive Mean/N (SD/%) (n = 27)|
|Age||29.2 (6.1)||29.0 (6.4)||29.5 (6.5)||29.7 (6.8)|
|Female||71 (96%)||35 (95%)||56 (97%)||25 (93%)|
|BPD criteria (SCID)||6.7 (1.1)||6.9 (1.3)||6.7 (1.1)||6.8 (1.3)|
|At least one other PD||48 (65%)||32 (86%)||42 (72%)||23 (85%)|
|Number of Axis I diagnoses||2.1 (1.3)||1.4 (1.1)||2.0 (1.3)||1.3 (1.0)|
| Single||37 (50%)||14 (38%)||28 (48%)||10 (37%)|
| Successive partners||18 (24%)||10 (27%)||12 (21%)||6 (22%)|
| Married/partner||19 (26%)||13 (35%)||18 (31%)||11 (41%)|
|Years of education|
| <10||35 (47%)||13 (35%)||28 (48%)||9 (33%)|
| 10–12||26 (35%)||19 (51%)||19 (33%)||14 (52%)|
| 13–15||13 (17%)||3 (8%)||11 (19%)||2 (7%)|
| >15||0 (0%)||2 (5%)||0||2 (7%)|
| Employed||7 (10%)||2 (5%)||6 (10%)||2 (7%)|
| Student||12 (16%)||6 (16%)||8 (14%)||5 (19%)|
| Social security||53 (72%)||25 (68%)||40 (69%)||15 (56%)|
| Pension||1 (1%)||4 (11%)||1 (2%)||4 (15%)|
|Reported self-mutilation||59 (80%)||30 (81%)||48 (83%)||21 (78%)|
|Reported (lifetime) suicide attempt||52 (70%)||23 (57%)||42 (72%)||17 (63%)|
|Antipsychotic drug treatment||7 (10%)||8 (22%)||6 (10%)||6 (22%)|
|Antidepressive drug treatment||45 (61%)||25 (68%)||37 (64%)||20 (74%)|
|No drug treatment||22 (30%)||12 (32%)||17 (29%)||6 (22%)|
In line with prior BPD studies, most of the patients were burdened by relatively severe socio-economic problems. Almost half of them were living alone, while one-quarter had several successive partners. A substantial proportion of the patients (over 65%) were on social security. Compared with the Danish population in general, the level of education in the group of patients was very low. T-tests, Fisher’s exact tests and chi-square tests were conducted on all clinical and demographic data at intake. Three significant differences between the two groups were identified at intake (patients starting treatment). First, the number of patients on permanent social security (pension) was significantly higher (P < 0.04) in the supportive group, and second, axis I comorbidity was significantly higher (P < 0.02) in the MBT treatment group. In the combined treatment group, 60% received a diagnosis of depression, 31% were diagnosed with an anxiety disorder and 45% had some form of eating disorder, compared with 46% diagnosed with depression, 19% with anxiety disorder and 32% with eating disorder in the group of patients randomized to supportive treatment. Finally, significantly (P < 0.03) more of the patients randomized to supportive treatment had at least one other personality disorder. In the group of patients who started treatment, this difference was no longer significant (P = 0.27). No significant (P > 0.05) differences were identified between the group of patients who dropped out while on waiting list compared with the patients who started in treatment, nor between the group of patients who completed 2 years of treatment and the patients who started treatment but dropped out prematurely. No significant differences were found between those patients with complete data and those with incomplete data (all Ps > 0.11).
Means and standard deviations for the outcome measures are reported in Table 2. Average level of disturbance decreased significantly over the course of treatment in both groups. As can be seen from Table 2, patients in both treatment modalities showed clinically significant changes on all symptom measures. In combined MBT treatment, mean GSI dropped from 1.7 (SD = 0.6) at intake to 1.2 (SD = 0.8) at 24 months. Similarly, patients in supportive treatment showed a drop in GSI mean from 2.0 (SD = 0.6) at intake to 1.4 (SD = 0.8) after 24 months. Fourteen (24%) patients in combined and four (15%) patients in supportive treatment moved from a GSI score above to a GSI score below 0.6 (cut-off for pathology) (difference ns, P > 0.40). Self-reported depression (BDI) decreased substantially in both groups. In the course of treatment, 22 (38%) patients in the combined treatment group and thirteen (48%) patients in the supportive treatment group moved from a BDI score above to a BDI score below 29 (cut-off for severe depression) (difference ns, P > 0.47). At 24 months, the mean number of diagnostic criteria for BPD met had dropped from 6.7 (SD = 1.2) at intake to 2.8 (SD = 2.5) in the combined treatment group and in the supportive treatment group from 6.9 (SD = 1.3) at intake to 3.6 (SD = 2.2) at 24 months. At termination, thirty (52%) patients in the combined treatment group and eleven (41%) patients in the supportive group no longer met the diagnostic criteria for BPD (difference ns, P = 0.06).
Table 2. SCL-90-R-GSI, BDI, BAI, STAI-S/T, GAF-F/S, IIP, SAS-SR-scores and number of SCID-II BPD criteria met in patients with borderline personality disorder who received combined mentalization-based or supportive group therapy
|Time||SCL-90, GSI Mean (SD)||BDI Mean (SD)||BAI Mean (SD)||IIP Mean (SD)||STAI-T Mean (SD)||STAI-S Mean (SD)||GAF-F Mean (SD)||GAF-S Mean (SD)||SCID-BPD Mean (SD)||SAS-SR Mean (SD)|
| MBT (n = 58)||1.7 (0.6)||31.5 (10.7)||18.6 (9.0)||1.7 (0.6)||60.7 (8.6)||57.2 (11.0)||46.4 (7.5)||43.0 (2.8)||6.7 (1.2)||2.6 (0.4)|
| Supp (n = 27)||2.0 (0.6)||37.5 (10.6)||23.7 (11.2)||1.9 (0.6)||64.9 (5.3)||63.5 (8.9)||44.6 (8.2)||43.1 (3.8)||6.9 (1.3)||2.8 (0.6)|
| MBT (n = 52)||1.6 (0.7)||27.8 (11.7)||17.8 (11.4)|| || || || || || || |
| Supp (n = 20)||1.5 (0.8)||29.8 (16.0)||18.0 (10.7)|| || || || || || || |
| MBT (n = 44)||1.3 (0.6)||24.6 (12.2)||14.8 (9.3)|| || || ||50.5 (8.1)||48.5 (6.1)|| || |
| Supp (n = 17)||1.5 (1.0)||25.9 (16.0)||18.7 (14.9)|| || || ||47.3 (9.6)||48.0 (7.7)|| || |
| MBT (n = 41)||1.3 (0.7)||22.9 (12.7)||14.7 (10.4)|| || || || || || || |
| Supp (n = 17)||1.4 (0.9)||22.4 (18.0)||17.7 (17.0)|| || || || || || || |
| MBT (n = 42)*||1.2 (0.8)||18.8 (11.5)||13.5 (10.7)||1.2 (0.6)||49.3 (11.6)||47.3 (16.0)||56.7 (11.7)||58.5 (12.6)||2.8 (2.5)||2.2 (0.5)|
| Supp (n = 24)†||1.4 (0.8)||22.8 (13.7)||15.6 (10.1)||1.3 (0.8)||51.6 (16.8)||50.3 (17.6)||51.3 (11.7)||54.0 (10.5)||3.6 (2.1)||2.1 (0.6)|
Therapist-rated global level of functioning increased significantly in the MBT treatment group. In the supportive treatment group, only the GAF-S changed significantly. Normally, a GAF score above 60 is used as a cut-off for mild but persistent symptoms and some non-severe difficulties in social, occupational or educational functioning. At termination, 19 of the 42 patients (45%) in the combined treatment group had a GAF-S score above 60, while 15 of 42 (36%) had a GAF-F score above 60. In the supportive treatment group, only 4 of 24 patients (17%) had GAF scores (symptom and functioning) above 60 at termination (difference between groups significant for GAF-S, P = 0.03, ns for GAF-F, P = 0.16).
Linear regression analysis showed highly significant time (number of days from assessment until 750 days after the treatment was started) by outcome interactions for all outcome measures in the combined treatment group, indicating that all reported changes were highly statistically significant (most Ps < 0.0005). All changes reported in the supportive treatment group except BAI and GAF-F were also statistically significant (most Ps < 0.008) (Fig. 2).
Figure 2. Development in SCL-90-R, GSI score (Symptom Check List-90-Revised, Global Severity Index), t(0)–t(24 months), for patients with borderline personality disorder who received combined mentalization-based treatment or supportive group therapy.
Download figure to PowerPoint
Moreover, 34% of patients in combined treatment and 48% of patients in supportive therapy had their medication significantly reduced or withdrawn while in treatment (difference ns, P = 0.24). Only 16% in combined and 7% in supportive therapy had their medical treatment intensified during the course of treatment (difference ns, P = 0.49).
The influence of axis I diagnosis on treatment outcome was analysed using a generalized linear model with outcome measures as dependent variable and the interaction between time (number of days) and the presence/absence of each axis I diagnosis (depression, anxiety, eating disorder and OCD) as essential independent variable. None of these interactions were significant (Bonferroni corrected P > 0.005). Two interesting trends were found in the MBT group when focusing on SCID-II-measured treatment outcome (number of BPD criteria met): treatment outcome was lower in patients with comorbid eating disorder (P = 0.06), and patients with comorbid anxiety experienced higher treatment outcome (P = 0.02).
Pre-post effect sizes (Cohen’s d) were calculated based on those patients who started treatment. In both groups, a large or very large (0.5–2.1) and in most cases highly significant (all Ps < 0.01, in the MBT group most Ps < 0.00005) effect sizes on all measures of outcome were found. Only two effect sizes, one in each group (see Table 2), were below 0.8 (cut-off for large effect sizes). In the MBT group, SCID-II-based effect size (Cohen’s d) was 2.48 for patients without comorbid eating disorder and 1.78 for patients with comorbid eating disorder, 2.29 and 1.81 for patients without and with comorbid anxiety respectively (this apparently inconsistent finding for patients with comorbid anxiety was owing to high SDs used in calculating Cohen’s d).
Differences in outcome between the two randomized groups were analysed using a general linear model with treatment group and patient as factors, and time as the independent variable. For self-report measures of depression, anxiety, social functioning, interpersonal function and general level of functioning, we found no statistically significant differences between the two groups (all Fs < 2.9, all Ps > 0.13). Differences across individual patients in the two treatment groups were high, indicating that some patients experienced much better outcomes than others. Only therapist-rated global level of functioning showed statistically significant differences between the two groups. Compared with patients in supportive group treatment, changes on both GAF-S and GAF-F were significantly higher in the MBT group (GAF-F: F = 8.0, P = 0.005; GAF-S: F = 12.7, P = 0.0004). Because of the abnormal distribution of the GAF data, the analyses of our GAF data were repeated using GAF data subjected to log transformation. Again, changes in both GAF-S and GAF-F were significantly higher in the MBT group compared with the supportive group (GAF-F: F = 7.5, P = 0.007; GAF-S: F = 13.8, P = 0.0002).
- Top of page
- Significant outcomes
- Material and methods
- Declaration of interest
Contrary to our expectations (given the higher intensity and specific focus on BPD in the MBT group), outcome of the combined MBT therapy was only superior to the less-intensive supportive group therapy on therapist-rated GAF. Our findings indicate that both intensive combined MBT treatment and less-intensive supportive group therapy lead to significant improvements on a variety of psychological and interpersonal measures. Although most patients continued to suffer from moderate levels of symptoms after 2 years of treatment, patients in both treatment modalities showed significant clinical and highly statistically significant improvements. This is evidenced by strong effect sizes on most measures, including specific borderline pathology (reflected in the number of diagnostic criteria met), self-reported state/trait anxiety, social function and depressive symptoms/comorbid depression. One could argue that the observed improvements in self-reported depressive symptoms could be the result of antidepressant medication. However, this explanation is unlikely, as a substantial proportion (39%) of the patients had their medication withdrawn or significantly reduced during the course of treatment (22% were not in medical treatment at any point), a finding in accordance with studies showing that patients receiving specialist PD services are less likely to be in drug treatment (44). Moreover, the observed improvements in levels of depression were accompanied by improvements in other areas, such as interpersonal functioning, social adjustment and general level of functioning. This finding could be interpreted as an indication that depressive symptoms in borderline patients are related to a general affective dysregulation rather than an affective disorder per se (45).
The fact that significant differences in outcome across the two treatments were not identified suggests that there could be various routes to symptom change among borderline patients. Compared with those in supportive therapy, patients in the combined treatment group received significantly more intensive therapy making it more surprising that almost all differences in outcome were statistically non-significant. Our findings suggest that long-term supportive group therapy at a relatively low intensity can have a significant effect on borderline patients. This interpretation is supported by Clarkin et al. (28), who reported significant outcomes from long-term psychodynamic supportive therapy of relatively low intensity. These outcomes are comparable with those obtained in transference-focused therapy and dialectical DBT of a higher intensity.
One could argue that the finding that medium-intensity supportive group therapy is equally effective as high-intensity mentalization-based therapy may compromise mentalization-based therapy as an effective treatment model. However, as both treatment modalities lead to significant positive outcomes, further research is necessary. For example, the effectiveness of both treatments following treatment completion is unknown. One could speculate that supportive group therapy of lower intensity, while serving to stabilize borderline patients during treatment, may be unable to bring about more lasting changes in these patients. In contrast, the more intensive mentalization-based treatment may be accompanied by more permanent or structural changes. The rate of recovery from BPD was higher (52%) in the MBT than in the supportive group (41%) and the mean number of BDP criteria met dropped from 6.7 to 2.8 for patients in combined treatment whereas the observed drop was slightly lower for patients in supportive therapy from 6.9 to 3.5. These observed differences are only trends and not statistically significant. Thus, more direct assessments and follow-up data are needed to make more substantial conclusions about possible differences in the ability of the two treatments models to initiate more lasting or structural changes.
If patients in medium-intensity supportive group therapy – combined with medical treatment, psycho-educational groups and access to crisis management – continue to show symptomatic improvements (with larger samples and follow-up data available), this would emphasize the need to develop supportive treatment models and to conduct controlled outcome studies of less-intensive supportive therapy with BPD patients. It should also be kept in mind that the two therapists conducting the supportive treatment in this study were highly experienced and part of a highly structured clinic specializing in the treatment of BPD. Thus, the lack of significant differences in outcomes between the two groups could be related to the fact that both treatment models were practiced in a well-structured clinic by highly experienced clinicians. In addition to this, one could ask if therapist factors (personal qualities, level of experience, general therapeutic competence, etc.), the therapy being embedded in a well-organized clinic and other non-specific factors (46, 47) are at least as important and possibly more important for treatment outcome in BPD patients than more specific (in some cases manualized) technical factors – the focus of RCTs and the empirically based treatment movement – including whether patients are offered mentalization-based or supportive group therapy. One could also argue that well-trained psychodynamically oriented clinicians with knowledge of mentalization, attachment, object relations theories and extensive experience in working with PD patients have a broader and deeper understanding of BPD, which makes them better able to be flexible and creative in responding to the various needs of these patients. This could narrow the difference between the two treatment arms and in effect the differences in outcome in the two groups. Thus, the results of this study could be significant in demonstrating that a well-trained, experienced and well-supervised psychodynamic staff is very helpful in treating BPD.
Given the heterogeneity of borderline patients, it is highly unlikely that any one treatment will be equally useful for all patients and future studies should examine the possible interaction between patient, treatment, therapist characteristics and treatment intensity. Such studies would help establish which form of treatment, delivered by whom (‘what kind of therapist’), would be most effective for a variety of BPD patients experiencing a variety of different problems. Results from this study support the idea that there is no ‘one-size-fits-all’ manualized treatment for BPD. Based on our findings and the findings of Clarkin et al. (28) and McMain et al. (21), we hypothesize that not all borderline patients need intensive long-term treatment and that some may profit from organizationally well-structured supportive therapy of medium intensity, while others need more intensive treatment. Supportive group therapy may be sufficient for a subgroup of borderline patients whereas more intensive (MBT, DBT or TFP) treatment may be necessary for another (presumably broader) subgroup of BPD patients. This argument is partially supported by the high variance in outcomes found in the present study. One could argue that the use of interpretations, MBT chain analyses and persistent focus on mental states in the here and now can be highly stressful and alienating for some BPD patients, especially in the early stages of treatment. In these patients, and in patients with severely compromised ability to construct mental representations of mental states, a more supportive approach might be more helpful.
Given the complicated nature of BPD, it is essential to establish the long-term outcomes of treatment. Therefore, the ability to maintain improvements obtained in treatment following termination is a very important variable when evaluating the effectiveness of different treatment models. Consequently we are in the process of collecting 1½- and 5-year follow-up data from the two treatment groups.
One limitation of the study is that the two compared treatments were not based on detailed treatment manuals and our design did not include ongoing systematic monitoring of the two treatment modalities (adherence and competence ratings). However, one could argue that the idea of ‘controlled treatment’, based on specific manualized guidelines and continuous monitoring to ensure that the treatment offered adheres to manual guidelines, is premised on the highly theoretical and probably illusory idea that BPD therapy can be reduced to a limited set of specific technical interventions. Our more naturalistically informed design provides better generalizability to the community (effectiveness). In spite of this, it should be acknowledged that the absence of thorough adherence and competence measures makes it difficult to determine if the compared treatment models were optimally tested. Second, although treatment integrity, differentiability and our therapist’s adherence to the relevant treatment models were supported and monitored through close, video-based supervision and theoretical training, one could argue that the two treatment arms were not sufficiently distinct as they were conducted in the same clinic and by the same therapists. The two supportive therapists were also conducting mentalization-based psychotherapy with patients in the MBT treatment group. We have been involved in the development of an instrument for extensive adherence rating of MBT treatment (48). However, this work was not completed at the time of the present study, but can enrich future studies. It is possible that the actual difference between the two delivered treatments is too small and that we in effect have conducted a component design study. If this is the case, our post-treatment findings suggest that outcomes are not significantly improved by adding intensive individual therapy to a group treatment, a finding that would support the ‘less is more’ principle (49, 50), at least for some BPD patients.
Attrition from the study is relatively high (approximately 43% of included patients with intention to treat, 26% of patients starting treatment), but comparable with most other studies in the field (6, 7). This issue is related to challenges that continually need to be addressed when working clinically and conducting research with borderline patients. At the end of treatment, we were able to collect data from approximately three-quarters (78%) of the patients who started in therapy, which is acceptable, especially when studying severely disturbed BPD patients. A substantial proportion of the patients were female BPD patients in their twenties or thirties. Therefore, it remains unclear to what extent the results presented can be generalized to the treatment of younger and/or older borderline patients and to male patients.
Outcome was tested almost exclusively by using self-report symptom measures. We are thus unable to assess possible – and from a theoretical perspective highly important – changes in more complex levels of functioning such as reflective functioning/ability to mentalize, attachment style, more structural variables like identity integration, etc. (51, 52). Changes in these aspects of BPD can be evaluated only indirectly. The absence of interview-based measures by independent assessors also resulted in the absence of blind (blind to treatment group) assessments of treatment outcome. The fact that GAF was rated by therapists, who were not blind to treatment arm and by team consensus (including the therapists treating the rated patients), could compromise the validity of the GAF ratings. And one could ask if it is a coincidence that the only significant group difference was found in one of the two therapist-rated outcome measures. In addition to this, our GAF outcome data were not normally distributed and the observed differences in GAF-rated treatment outcome between the two groups must be interpreted with caution. On the other hand, the reliability of the GAF ratings was high and the observed differences were highly statistically significant (including analyses based on normally distributed log-transformed data set), supporting the idea that our GAF data convey differences in outcome between the two groups of some clinical importance. Average level of functioning at the end of treatment is in the 51–60 range in both groups, corresponding to moderate symptoms and difficulties in functioning.
The skewed randomization of patients in to the two treatment modalities, which was dictated partly by a desire on the part of clinic’s management to offer intensive treatment to as many borderline patients as possible, and partly by available treatment resources, reduced statistical power. Statistical power was further reduced by the relatively high attrition rate and by the loss of some self-report data at certain stages owing to some patients’ refusal to complete all assessments at the assigned time points. Finally, we cannot rule out the possibility that individuals who would not benefit from the treatments offered were more likely to dropout, which would weaken our conclusion that both combined MBT treatment and supportive group therapy are effective in helping patients with BPD.