Cognitive-behavioural therapy and motivational intervention for schizophrenia and substance misuse: 18-month outcomes of a randomised controlled trial
Haddock G, Barrowclough C, Tarrier N, Moring J, O'Brien R, Schofield N, Quinn J, et al.;
Commented by , 21 Nov 2003
Aim of the study
Substance abuse is an important problem in people with schizophrenia. The incidence is high and substance abuse is associated with poor clinical and social outcomes. Not much is known about the optimum pharmacological treatment for this condition. Neither are there many sound studies on psychological treatments for this population, and there is not a lot of evidence on their long-term effects.
The researchers are specialists in the field of cognitive-behavioural treatment (CBT) for people with schizophrenia and have authored a number of landmark studies about this intervention. The current publication reports long-term effects of an individual, family-oriented programme on symptoms, substance use, functioning and health economy outcomes of patients with schizophrenia and concurrent substance misuse.
Methods
The authors conducted a randomised controlled trial which compared a combined motivational intervention, CBT (about 29 sessions) and family intervention (10-16 sessions) with routine care alone in patients with a dual diagnosis of schizophrenia and substance abuse. The patients were then assessed on multiple outcomes at 18-month follow-up. Carers were assessed on symptoms, functioning and needs over12 months. The researchers also collected cost data over 18 months. The assessors were blind to therapy group.
Results
36 patients and carers were randomized to the two groups. The treatment group had significantly better global functioning as assessed by the Global Assessment of Functioning scale, and fewer negative symptoms. There were additional advantages of the intervention e.g. in terms of relapse rates or the number of days abstinent, but these did not reach statistical significance.
There were no significant differences in terms of carer outcomes, although there were trends suggesting lower carer needs and burden in the intervention group. Cost outcomes showed no significant differences between groups, pharmacological and other treatments were not controlled.
Discussion
The study showed that the CBT intervention was superior to routine care on outcomes relating to illness and service use, and that the cost were not higher compared to the control treatment. An obvious limitation is the small sample size of only 36 patients randomised.
With more participants and thus more statistical power more findings might have reached statistical significance. Another limitation is the inclusion of only patients who had a minimum contact to the carer (10 hours). It is therefore unclear whether the results can be generalised to patients living without contact to their families.
Still, the results are remarkable and consistent with previous trials. Global functioning and negative symptoms improved most. This finding is consistent with the key targets of the CBT intervention. Whereas previous studies had also shown that CBT can have an effect on positive symptoms over longer periods of time, such effects were not maintained at the 18months follow-up of this study.
Although there were trends towards better outcomes of the carers as well, these did not reach statistical significance. This lack of significance may be due to the small sample size. Another explanation is that the carer intervention was relatively short and that longer efforts are needed to improve their outcomes.
Finally, the CBT intervention was not more costly than standard care. More (although not statistically significantly more) inpatient days in the control group have probably offset the higher therapy costs in the experimental group. In summary, this study shows that CBT is a promising strategy for the treatment of people with schizophrenia and concomitant substance abuse.