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Influence of therapist competence and quantity of cognitive behavioural therapy on suicidal behaviour and inpatient hospitalisation in a randomised controlled trial in borderline personality disorder: Further analyses of treatment effects in the BOSCOT study
Author(s) -
Norrie John,
Davidson Kate,
Tata Philip,
Gumley Andrew
Publication year - 2013
Publication title -
psychology and psychotherapy: theory, research and practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.102
H-Index - 62
eISSN - 2044-8341
pISSN - 1476-0835
DOI - 10.1111/papt.12004
Subject(s) - randomized controlled trial , randomization , competence (human resources) , borderline personality disorder , personality , psychology , clinical psychology , medicine , personality disorders , psychiatry , physical therapy , social psychology , surgery
Objectives We investigated the treatment effects reported from a high‐quality randomized controlled trial of cognitive behavioural therapy ( CBT ) for 106 people with borderline personality disorder attending community‐based clinics in the UK N ational H ealth S ervice – the BOSCOT trial. Specifically, we examined whether the amount of therapy and therapist competence had an impact on our primary outcome, the number of suicidal acts , using instrumental variables regression modelling. Design Randomized controlled trial. Participants from across three sites ( L ondon, G lasgow, and A yrshire/ A rran) were randomized equally to CBT for personality disorders ( CBT pd) plus Treatment as Usual or to Treatment as Usual. Treatment as Usual varied between sites and individuals, but was consistent with routine treatment in the UK N ational H ealth S ervice at the time. CBT pd comprised an average 16 sessions (range 0–35) over 12 months. Method We used instrumental variable regression modelling to estimate the impact of quantity and quality of therapy received (recording activities and behaviours that took place after randomization) on number of suicidal acts and inpatient psychiatric hospitalization. Results A total of 101 participants provided full outcome data at 2 years post randomization. The previously reported intention‐to‐treat ( ITT ) results showed on average a reduction of 0.91 (95% confidence interval 0.15–1.67) suicidal acts over 2 years for those randomized to CBT . By incorporating the influence of quantity of therapy and therapist competence, we show that this estimate of the effect of CBT pd could be approximately two to three times greater for those receiving the right amount of therapy from a competent therapist. Conclusions Trials should routinely control for and collect data on both quantity of therapy and therapist competence, which can be used, via instrumental variable regression modelling, to estimate treatment effects for optimal delivery of therapy. Such estimates complement rather than replace the ITT results, which are properly the principal analysis results from such trials. Practitioner points Assessing the impact of the quantity and quality of therapy (competence of therapists) is complex. More competent therapists, trained in CBT pd, may significantly reduce the number of suicidal act in patients with borderline personality disorder.