© 2006 The Royal College of Psychiatrists
Correspondence |
Cognitive–behavioural therapy for bipolar disorder
Department of Psychological Medicine, PO Box 96, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK.
Department of Psychiatry, University of Cambridge, UK
Department of Psychiatry, Royal Liverpool University Hospital, UK
Department of Psychology, University of Manchester, UK
Department of Clinical Psychology, University Psychology, University of Liverpool, UK
Medical Research Council Biostatistics Unit, Institute of Public Health, Cambridge, UK
Department of Psychiatry, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK
Correspondence: E-mail: j.scott{at}iop.kcl.ac.uk
EDITED BY KIRIAKOS XENITIDIS and COLIN CAMPBELL
Dr Lam (2006) comments on our study (Scott et al, 2006a), the largest randomised controlled trial (RCT) of psychological treatment for bipolar disorder conducted so far. We respond as follows.
- Dr Lam seems to misinterpret the nature and purpose of pragmatic trials. It
is not a matter, as he suggests, simply of appropriate outcome measures, which
should be a feature of all trials. Pragmatic trials are intended to test
therapies in the practical circumstances of everyday clinical settings, using
large multicentre samples (Hotopf et
al, 1999). Most previous trials of therapies for bipolar
disorders were single-centre efficacy studies designed to try out new
interventions in specialist services or where the originator worked.
- Dr Lam comments on the number of cognitive–behavioural therapy (CBT)
sessions received. We believe that 20 sessions with 2 boosters is as many as
is practical in most National Health Service (NHS) settings. That patients
attended about 14 of the sessions offered is frustrating but reflects clinical
reality and is remarkably similar to the attendance achieved in Dr Lam’s
own study (Lam et al,
2003: average 13.9 sessions, s.d.=5.5).
- Our analysis strategy was determined before inspection of the data under
the scrutiny of a trial steering committee appointed by the Medical Research
Council. Dr Lam confounds several issues and recommends an actuarial analysis
that is fundamentally incorrect in the context of an RCT
(ICH Harmonised Tripartite Guideline,
1999). In an intention-to-treat analysis, the date of
randomisation determines the start of the clock and everyone who is randomised
is analysed; it is wrong to delay the inclusion of any participant in the
analysis until they are asymptomatic. We also reported in the text on the
issue he raised, namely that there was no difference in time to next bipolar
episode or mean severity of symptoms in the sample who were in acute bipolar
episode at baseline, not in acute bipolar episode at baseline or the whole
sample.
- Dr Lam suggests it was inappropriate to include in our study individuals
who were in a current episode or not on mood stabilisers. However, given that
RCTs of therapy for mental disorders are usually undertaken with participants
who are currently symptomatic, we believe it is important and informative to
explore the potential effects of therapies commenced in the acute phase of
bipolar disorder. Furthermore, in Judd et al’s
(2002) 12-year follow-up it was
shown that individuals with bipolar disorder spend 50% of their time with
syndromal or sub-syndromal symptoms of mood disorder, predominantly
depression. Not receiving or not adhering to recognised mood stabilisers is a
similar well-documented issue in 20–50% of individuals with bipolar
disorders (Scott & Colom,
2005). Our sample thus reflects the realities of clinical
practice.
- It is standard practice in RCTs to control for design variables and also to
pursue additional analyses that control for potential confounders
(Schulz & Grimes, 2005).
None of our analyses failed to converge, a common consequence of
multi-collinearity.
- Dr Lam points out that a median split of a continuous variable can lose
information. In fact, this was the reason why we looked for a trend across
four groups as shown in Fig. 4 (p. 318).
Previous studies of psychological therapies have mostly involved more selected populations at relatively lower risk of relapse. In those circumstances CBT appears beneficial. Our study used a mixed patient sample; many were high-risk or currently symptomatic. We designed the trial in this way to address an issue not explored so far in any other psychological therapy study, namely whether the treatment would be effective in all patients who might be considered for it. Patients were only excluded if participation was unfeasible or unethical.
Our findings indicate that 22 sessions of CBT may not be effective for most people seen in NHS general adult psychiatry settings. In our lower-risk subgroup, similar in characteristics to Dr Lam’s sample (Lam et al, 2003), CBT may be very helpful. The clinical implications are that for a stable, lower-risk population, early in their history of bipolar recurrences, CBT should be considered as an adjunctive treatment option to further enhance their outcome. For high-risk, complex cases, other forms of therapy should be considered, such as those targeted at medication adherence or relapse prevention, before considering CBT. These recommendations are consistent with the results from published meta-analyses and other findings on psychological therapies in bipolar disorders (Scott & Colom, 2005; Scott et al, 2006b).
REFERENCES
- Hotopf, M., Churchill, R. & Lewis, G.
(1999) Pragmatic randomised controlled trials in psychiatry.
British Journal of Psychiatry,
175, 217
–223.
[Abstract/Free Full Text] - Judd, L. L., Akiskal, H. S., Schlettler, P. J., et al
(2002) The long-term natural history of the weekly
symptomatic status of bipolar 1 disorder. Archives of General
Psychiatry, 59, 530
–537.
[Abstract/Free Full Text] - ICH Harmonised Tripartite Guideline (1999) Statistical principles for clinical trials Statistics in Medicine, 18, 1905 –1942.[Medline]
- Lam, D., Watkins, E., Hayward, P., et al (2003) A randomized controlled trial of cognitive therapy of relapse prevention for bipolar disorder: outcome of the first year. Archives General Psychiatry, 60, 145 –152.
- Lam, D. (2006) What can we conclude from
studies on psychotherapy in bipolar disorder? Invited commentary on:
Cognitive–behavioural therapy for severe and recurrent bipolar
disorders. British Journal of Psychiatry,
188, 321
–322.
[Abstract/Free Full Text] - Schulz, K. F. & Grimes, D. A. (2005) Multiplicity in randomised trials II: subgroup and interim analyses. Lancet, 365, 1657 –1661.[CrossRef][Medline]
- Scott, J. & Colom, F. (2005) Psychosocial treatments for bipolar disorders. Psychiatric Clinics of North America, 28, 371 –384.[CrossRef][Medline]
- Scott, J., Paykel, E., Morriss, R., et al
(2006a) Cognitive–behavioural therapy for
severe and recurrent bipolar disorders. Randomised controlled trial.
British Journal of Psychiatry,
188, 313
–320.
[Abstract/Free Full Text] - Scott, J., Colom, F. & Vieta, E. (2006b) A meta-analysis of adjunctive psychological therapies compared to usual psychiatric treatment for bipolar disorders. International Journal of Neuropsychiatry, in press.
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