Health Technology Assessment 2005; Vol 9: number 42
Executive SummaryView/Download full monograph in Adobe Acrobat format (1.21 mbytes)
RC Durham,1* JA Chambers,1,2 KG Power,2,3 DM Sharp,4 RR Macdonald,2 KA Major,5 MGT Dow2,6 and AI Gumley7
1 Psychiatry and Behavioural Sciences, Division of Pathology and Neuroscience, University of Dundee, UK
2 Department of Psychology, University of Stirling, UK
3 Department of Clinical Psychology, NHS Tayside, UK
4 Institute of Rehabilitation, University of Hull Medical School, UK
5 Health Economics, NHS Ayrshire and Arran, UK
6 Department of Clinical Psychology, NHS Fife, UK
7 Department of Psychological Medicine, University of Glasgow, UK
* Corresponding author
The aim of this study was to consider the following:
An attempt was made to contact and interview all of the participants in eight randomised, controlled, clinical trials of CBT for anxiety disorders and two randomised, controlled, clinical trials of CBT for schizophrenia conducted between 1985 and 2001. Case note reviews of healthcare resources used in the 2 years prior to entering the trials and the 2 years prior to follow-up interview were undertaken.
The clinical trials were conducted in mixed rural and urban settings in five localities in central Scotland. Anxiety disorder trials were conducted mainly in primary care and included three with generalised anxiety disorder, four with panic disorder and one with post-traumatic stress disorder (PTSD). The psychosis studies (one on relapse prevention and one with chronic disorder) were conducted in secondary care.
An attempt was made to follow up all 1071 entrants to the 10 studies, of whom 125 were not available to be contacted. Of the 946 who were available, 489 agreed to participate (46% of original entrants, 52% of those available to contact).
Follow-up interviews took place between 1999 and 2003, 214 years after the original treatment. Interviews for Trials 18 were conducted by a research psychologist blind to original treatment condition. Interviews for Trials 9 and 10 were conducted by community psychiatric nurses also blind to treatment condition. Case note reviews were completed following the interview.
For Trials 18 the main interview-based outcome measures were: Anxiety Disorders Interview Schedule DSM-IV for diagnosis and co-morbidity, Clinical Global Severity (08) and the Hamilton Anxiety Rating Scale. The main patient-rated measures were: Brief Symptom Inventory, SF-36 II, Clinical Global Improvement (17), and the Positive and Negative Affect Scale. For Trials 9 and 10 the primary outcome measure was the interview-based Positive and Negative Syndrome Scale (PANSS).
Over half of the participants (52%) had at least one diagnosis at long-term follow-up, with significant levels of co-morbidity and health status scores comparable to the lowest 10% of the general population. Few participants had none or only mild symptoms (18%) and a significant proportion (30%) had subthreshold symptoms of at least moderate severity. Only 36% reported receiving no interim treatment for anxiety over the follow-up period with 19% receiving almost constant treatment. Patients with PTSD did particularly poorly. There was a 40% real increase in healthcare costs over the two time periods, mainly due to an increase in prescribing. A close relationship was found between poor mental and physical health for those with a chronic anxiety disorder.
Treatment with CBT was associated with a better long-term outcome than non-CBT in terms of overall symptom severity but not with regard to diagnostic status. The positive effects of CBT found in the original trials were eroded over longer time periods. No evidence was found for an association between more intensive therapy and more enduring effects of CBT. Long-term outcome was found to be most strongly predicted by the complexity and severity of presenting problems at the time of referral, by completion of treatment irrespective of modality and by the amount of interim treatment during the follow-up period. The quality of the therapeutic alliance, measured in two of the studies, was not related to long-term outcome but was related to short-term outcome.
The cost-effectiveness analysis showed no advantages of CBT over non-CBT. For the participants as a whole, CBT was associated with slightly higher costs than non-CBT and slightly higher benefits. For participants who completed CBT, versus all other participants, CBT was associated with somewhat lower costs and slightly higher benefits. The costs of providing CBT in the original trials was only a very small proportion (6.4%) of the overall costs of healthcare for this population, which are high for both physical and mental health problems.
Outcome was generally poor and only 10% achieved a 25% reduction in total PANSS scores from pretreatment to long-term follow-up. Nearly all participants (93%) reported almost constant treatment over the follow-up period at a significantly higher level than for the anxiety disorder patients. Treatment with CBT was associated with more favourable scores on the three PANSS subscales. However, there were no significant differences between CBT and non-CBT groups in the proportions achieving clinically significant change and very few psychosis patients maintained a 25% reduction in PANSS scores from post-treatment to long-term follow-up regardless of treatment modality.
Cost-effectiveness analysis showed no advantages of CBT over non-CBT. Healthcare costs fell over the two time periods mainly owing to a reduction in inpatient costs.
The implications for healthcare are:
Longitudinal research designs over extended periods of time (25 years), with large numbers of participants (500+), are required to investigate the relative importance of patient characteristics, therapeutic alliance and therapist expertise in determining the cost-effectiveness of CBT in the longer term.
A better understanding of the mechanisms by which poor treatment responders become increasingly disabled by multiple physical and mental disorders will require close collaboration between researchers in the clinical, biological and social sciences.
Durham RC, Chambers JA, Power KG, Sharp DM, Macdonald RR, Major KA, et al. Long-term outcome of cognitive behaviour therapy clinical trials in central Scotland. Health Technol Assess 2005;9(42).
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