School of Psychiatry and Behavioural Sciences, University of Manchester
Tameside & Glossop Community & Priority NHS Trust
School of Psychiatry and Behavioural Sciences, University of Manchester
Tameside & Glossop Community & Priority NHS Trust
Centre for Health Economics, University of York
School of Psychiatry and Behavioural Sciences, University of Manchester
Tameside & Glossop Community Priority NHS Trust
FRCPsych, School of Psychiatry and Behavioural Sciences, University of Manchester, UK
Correspondence: Dr G. Haddock, Academic Department of Clinical Psychology, University of Manchester, Education and Research Centre, Wythenshawe Hospital, Southmoor Road, Manchester M23 9LT, UK
Declaration of interest None. Funding detailed in Acknowledgements.
See editorial, pp.
377378, this
issue.
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ABSTRACT |
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Aims To investigate symptom, substance use, functioning and health economy outcomes for patients with schizophrenia and their carers 18 months after a cognitivebehavioural treatment (CBT) programme.
Method Patients with dual diagnosis from a randomised controlled trial of motivational intervention, individual CBT and family intervention were assessed on multiple outcomes at 18-month follow-up. Carers were assessed on symptom, functioning and needs over12 months. Health economy data were collected over 18 months.
Results There were significant improvements in patient functioning compared with routine care over18 months. No significant differences between treatment groups were found in carer or cost outcomes.
Conclusions The treatment programme was superior to routine care on outcomes relating to illness and service use, and the cost was comparable to the control treatment.
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INTRODUCTION |
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METHOD |
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Subjects
Subjects were entered into the trial as patient and carer pairs. Inclusion
criteria were: an ICD10 (World
Health Organization, 1992) and DSMIV
(American Psychiatric Association,
1994) diagnosis of schizophrenia, schizoaffective disorder or
delusional disorder; a DSMIV diagnosis of substance dependence or
misuse; in contact with catchment-area-based mental health services in the
north-west of England; aged between 18 and 65 years; and face-to-face contact
with a carer for a minimum of 10 h per week. Patients were excluded if there
was evidence of organic brain disease or learning disability. Potential
subjects were identified by screening hospital records from the mental health
units of three UK National Health Service (NHS) hospital trusts (Tameside
& Glossop, Stockport and Oldham). Patients were approached first for
consent and, after a complete description of the study, the written informed
consent of those agreeing to participate was obtained. Carers then were
approached and the same procedure followed. Only when both patient and carer
consented were the patients accepted into the study. Patients and relatives
were assessed on multiple measures (see below) before randomisation to one of
the two arms of the trial. Individual patients were allocated by a third party
with no affiliation to the study using a computer-generated randomisation list
stratified for gender and three types of substance use (alcohol alone, drugs
alone or drugs and alcohol).
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INTERVENTIONS |
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Outcome measures
The assessments were conducted by independent assessors (two psychology
graduate research assistants, N.S. and J.Q.). The assessors were blind to
treatment allocation, with attempts to maintain their blindness by using
separate rooms and administrative procedures for project staff, multiple
coding of treatment allocation and requesting subjects not to disclose
information about their treatment. Because the target patient group had
multiple problems related to the symptoms of substance use and psychosis, the
primary outcome for patients was change in the Global Assessment of
Functioning Scale (GAF; American
Psychiatric Association, 1994). Change in this outcome measure was
chosen because we felt that overall improvements in the presenting symptoms
and their functioning resulting from the interaction between psychosis and
substance use would be reflected in changes on this measure. Secondary
outcomes also were used, including measures of patient symptomatology (the
Positive and Negative Syndrome Schedule, PANSS;
Kay et al, 1988),
social functioning (the Social Functioning Scale, SFS;
Birchwood et al, 1990)
and patient substance use (timeline follow back, TLFB;
Sobell & Sobell, 1992).
Patient outcome assessments were administered at four time points:
pre-randomisation, immediately, post-intervention (9 months), at 12 months and
at follow-up (18 months).
Two variables were computed for evaluating outcome on the TLFB: percentage of days abstinent from the most frequently used substance; and percentage of days abstinent from all substances. The most frequently used substance was identified from the Addiction Severity Index (McLellan et al, 1980). The TFLB interviews were conducted every 3 months throughout the intervention. The concurrent validity of the TLFB had been established previously (Barrowclough et al, 2001).
Finally, two methods of assessing the frequency and duration of relapse were used for relapses in the 2 years prior to intervention and during the study period: the number and duration of hospital admissions identified from hospital record systems; and the number and duration of exacerbations of symptoms lasting longer than 2 weeks and requiring a change in patient management (increased observation and/or medication change by clinical team as assessed from chart review). Where symptom exacerbation preceded hospitalisation only one relapse was recorded. For relapses that preceded study entry by more than 2 years, only the number of admissions was assessed. Record systems were searched by the two assessors who were blind to patient study allocation. Interrater reliability for number and duration of exacerbations was checked by comparing ratings for ten randomly selected subjects, and there was 100% agreement.
Interrater reliability of the clinician-rated assessments for this study was good and has been reported previously (Barrowclough et al, 2001) for the treatment outcome data. Reliability of the GAF and PANSS was assessed also at the 18-month follow-up point. Interrater agreement for the GAF, based on agreement between the two raters on ten independent assessments, was good (interrater correlation coefficient=0.65). Interrater reliability of the PANSS, based on the percentage agreement on exact or one-point different rater scores from five audiotaped interviews, was also good for each PANSS sub-scale (PANSS positive=83.3%; PANSS negative=96.7%; PANSS general=98.7%).
Carer outcomes
Data on carer functioning were collected at baseline and at 9 and 12
months. Expressed emotion was assessed using the Camberwell Family Interview
(CFI; Leff & Vaughan,
1985) prior to randomisation. These data were only collected at
baseline. The 28-item General Health Questionnaire (GHQ;
Goldberg & Williams, 1988) and the Beck Depression Inventory (BDI;
Beck et al, 1961) were
used to assess general psychopathology in carers, and the psychosocial needs
of carers were assessed using the Relatives Cardinal Needs Schedule (RCNS;
Barrowclough et al,
1998). In addition, the burden and distress scales of the Social
Behaviour Assessment Schedule (SBAS; Platt
et al, 1980) were completed by carers.
Economic outcomes
The principal objective of the economic analysis was to assess the relative
costeffectiveness of the CBT+motivational intervention in comparison with
routine care alone. The analysis was undertaken from a societal perspective to
evaluate the impact of the treatment on a number of different parties,
including patients, the NHS, other providers of care and the wider
economy.
Direct health care costs were obtained by applying an appropriate unit cost to each recorded consultation, contact or episode of care. Data on secondary health care utilisation were obtained from the patients medical records. Details of primary care and community-based services, direct non-health care costs (e.g. travel, child-care) and indirect costs (productivity losses) were obtained from patient self-report using an adapted version of the Client Service Receipt Inventory (Knapp & Beecham, 1990).
Unit cost information was collected from the financial departments of the relevant agencies. Where local data were not available, these costs were supplemented by unit costs from national literature sources (e.g. Netten et al, 1999), drug formularies (e.g. British Medical Association & Royal Pharmaceutical Society of Great Britain, 1999), statistical surveys and similar sources. The additional treatment costs for the treatment intervention were calculated using a cost per minute taken from the mid-point of the relevant 19981999 salary scales. The additional costs of non-face-to-face activities (e.g. writing up notes, supervision) were also included in the estimate of therapy costs. Costs are reported in net present value terms by discounting costs by the annual rate of 6%, as recommended by the UK Treasury. All costs are reported in 1998/1999 values of pound sterling.
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RESULTS |
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Of the carers, 27 were female and 9 male; the mean age was 51 years (s.d.=12.12). The majority (24, 66.6%) were parents, six (16.6%) were partners and the remainder consisted of one sibling, one grandparent, two landladies and two ex-partners. Thirty-two carers consented to the CFI administration and, of these, 20 (62%) were high-expressed-emotion status. There was no statistical difference (Fishers exact test) in the distribution of high- and low-expressed-emotion carers between the groups (treatment group: 17 carers assessed, 11 (65%) high expressed emotion, 6 (35%) low expressed emotion; control group: 15 carers assessed, 9 (60%) high expressed emotion, 6 (40%) low expressed emotion). For all assessed carer variables there were no statistical or clinical differences between the groups at baseline.
There were three deaths during the 18-month follow-up period. All occurred during the first 9 months of the study: one was in the experimental group and two were in the control group. None was the result of suicide. At the 18-month follow-up, eight patients did not complete assessments (three from the treatment group and five from the control group). A total of nine carers were not available or refused consent to be assessed at 9 months (three under treatment and six controls, including carers of the deceased patients); and eleven carers were not available or refused consent to be assessed at 12 months (four under treatment and seven controls). Carers were not approached for assessment at 18 months.
Complete secondary medical records for the service outcome evaluation were available for all patients. Complete patient self-reports were available for 100%, 97%, 94%, 88% and 79% of the five follow-up (at 3, 6, 9, 12 and 18 months following entry to the study) assessment periods. Missing patient self-report data were imputed using the mean of the relevant treatment group.
Intervention participation
Carers and patients in the intervention group
Ten sessions were selected as the minimum dose required to
carry out both an individual and a family intervention of sufficient intensity
to have an impact on patient outcomes. Five carers received less than this
threshold for family intervention; the median number of sessions was 11, with
a range of 120. Three patients received less than the threshold for
individual CBT interventions; the median number of sessions was 22, with a
range of 029.
Analyses
All analyses were conducted on an intention-to-treat basis. Patient deaths
were treated as relapses, and subject attrition did not affect the analyses of
relapse or secondary health economy outcomes because they were assessed from
service records. Where scores from assessment measures deviated significantly
from a normal distribution, log-transformed scores were used, and where
distributions remained skewed or there was significant kurtosis,
non-parametric statistics were employed.
Patient outcomes
Symptoms and functioning
Table 1 gives the scores for
the treatment and control groups on the GAF and PANSS (actual means and
standard deviations are given in the tables, but the text reports adjusted
means and standard errors). To compare the effects between the groups on the
18-month outcome measures, analyses of covariance were used with the
pretreatment scores entered as the covariate. The treatment group had
significantly superior GAF scores at the 18-month follow-up (adjusted
mean=61.68 and s.e.=3.32 v. adjusted mean=51.77 and s.e.=3.42;
F={1,30}=4.26; P=0.048). The treatment group had reduced
PANSS positive subscale scores over time, whereas the control group had a
slight increase, although this difference was not significant (adjusted
mean=12.93, and s.e.=4.23 v. adjusted mean=13.87 and s.e.=4.27;
F={1,26}= 0.19, NS). At 18 months there was a significant advantage
for the treatment group over the controls on the PANSS negative sub-scale
(adjusted mean=10.27 and s.e.=2.25 v. adjusted mean=15.50 and
s.e.=5.71; F={1,26}=9.87; P=0.004). There was no difference
between the two groups for PANSS general or total sub-scale scores. There was
a trend towards a significant difference in favour of the treatment group
between SFS total scores at 18 months (adjusted mean=106.64 and s.e.=7.27
v. adjusted mean=100.23 and s.e.=10.02; F{1,25}=3.69;
P=0.066).
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Missing patient symptom and functioning data
In order to assess the influence of missing data on the 18-month patient
symptom and functioning results, the data on the GAF, PANSS and SFS were
subject to further analysis using STATA version 6 for PC
(STATACorp, 1997). This
approach assumed that data were missing at random and involved calculation of
adjustment weights to compensate for missing values. The probability of
providing 18-month follow-up data was predicted using baseline, 9- and
12-month scores in an unweighted logistic regression. The reciprocal of this
probability was then used as an adjustment (probability) weight using the
logit command in STATA in a weighted logistic regression to estimate the
treatment effects in the main analyses
(Everitt & Pickles, 1999).
This analysis revealed no differences in the overall significant difference
between the two groups and hence the missing data are not thought to have
caused any threat to the validity of the interpretation of the results.
Relapse
By 18 months, seven patients had had at least one relapse in the CBT group
compared with twelve in the control group. There was a total of 11 relapses in
the treatment group and 24 relapses in the control group. These differences
were not statistically significant.
With regard to the total number of days relapsed between the two groups, there was numerical superiority of the treatment group at all time points, with a trend towards statistical significance at 18 months (median for the treatment group=0 (0120), total days in exacerbation=424; median for the control group=29 (0280), total days in exacerbation=1119; U=100.0; P=0.063).
Substance misuse
At all points but one during the trial the treatment group had a greater
percentage of days abstinent relative to baseline than did the control group
as assessed by the TLFB, although the differences were not statistically
significant at any single time point.
Carer outcomes
Measures of carer psychopathology (BDI and GHQ scores) in both groups were
fairly stable over the 12-month period and there were no differences between
the groups. However, at 12 months there was a trend towards a statistically
significant difference in change scores on the carer needs measure (RCNS:
U=45.0, P=0.08), with the treatment group showing a
reduction in needs while the control group remained stable. There was a
similar trend for the SBAS objective burden change scores at 9 months
(U=60.0, P=0.09) and both objective and subjective burden at
12 months (objective: U=42.0, P=0.06; subjective:
U=44.5, P=0.08).
Economic outcomes
The results of the cost analysis are reported as mean values with standard
deviations, and as mean differences in costs with 95% confidence intervals.
Because costs were non-normally distributed (positively skewed), the
robustness of the parametric assumptions concerning mean differences in costs
was tested using non-parametric bootstrapping methods by performing 1000
replications of the original data
(Thompson & Barber, 2000). Both the parametric confidence intervals and the bootstrap confidence
intervals are reported. All the service outcome data were analysed using SPSS
10.0 and Microsoft Excel 2000. The bootstrap re-sampling was undertaken using
STATA 7.0 (all on PC).
Table 2 provides details of resource use over the 18-month follow-up period. Patients given routine care alone had more in-patient days but fewer day hospital and day centre attendances. Table 3 reports the total costs and mean cost differences (a negative mean difference indicates a cost saving in favour of the intervention) for the treatment programme and routine care alone. Overall there were no significant differences in mean total costs between the treatment programme and routine care alone (£1260; P=0.65). A further analysis was carried out by excluding the costs of the experimental treatment but there was still no significant difference in costs (£3248; P=0.25).
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A series of one-way sensitivity analyses were undertaken to explore the impact on the base-case results of changing several of the underlying assumptions of the costing exercise (e.g. changing the discount rate; excluding the cost of appointments where the patient was not at home for family support; and including the cost of in-patient days leave arising during the overall duration of a patients hospital). The results demonstrated that the base-case analysis was robust to the different assumptions employed in the costing analysis and the differences in costs remained non-significant.
Cost-effectiveness analysis
Cost-effectiveness was evaluated by relating the differential cost per
patient receiving each treatment to their differential effectiveness in terms
of the primary clinical outcome (GAF). The incremental cost-effectiveness
ratio (ICER) was calculated as the difference in mean cost divided by the
difference in the mean GAF scores at the end of follow-up. A
costacceptability curve was used to incorporate the uncertainty around
the sample estimates of mean costs and outcomes and the uncertainty about the
maximum or ceiling ICER that the decision-maker would consider acceptable
(Van Hout et al,
1994). The curve shows the probability that the data are
consistent with a true cost-effectiveness ratio falling below any particular
ceiling ratio, based on the observed size and variance of the differences in
both the costs and effects in the trial
(UK Prospective Diabetes Study Group,
1998; Delaney et al,
2000).
To reflect the uncertainty in the estimates of mean costs and effects, Fig. 2 presents a scatter plot of the mean differences in cost and GAF scores between the groups, estimated by repeated sampling as part of the bootstrapping exercise. The x-axis and y-axis divide the graph into four quadrants that represent the following scenarios for the treatment programme in comparison with routine care (clockwise from top right): (i) more effective and more costly; (ii) more effective and less costly; (iii) less effective and less costly; and (iv) less effective and more costly. The high concentration of points in quadrants (i) and (ii) indicates that the treatment programme appears more effective than routine care alone (although the scatter of points indicates that, in a small percentage of cases, there is a possibility that CBT will be more expensive and less effective than routine care alone). The wide dispersion of points above and below the x-axis, however, indicates that there is uncertainty about whether this apparent gain in outcome is achieved at a lower or higher cost. Clearly, if a gain in outcome is achieved at a higher cost, then the critical issue that determines whether the intervention is deemed cost-effective is how much (if any) the decision-maker is prepared to pay for an additional unit gain in health outcome.
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Using the bootstrapped data presented in Fig. 2, Fig. 3 presents the cost-effectiveness acceptability curve of the intervention. The curve indicates the probability of treatment being more cost-effective than the control for a range of potential maximum amounts (ceiling ratio) that a decision-maker is willing to pay for an additional point increase in the GAF. The x-axis shows a range of values for the ceiling ratio and the y-axis shows the probability that the data are consistent with a true cost-effectiveness ratio falling below these ceiling amounts.
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Figure 3 demonstrates that the probability of treatment being less costly than routine care (i.e. the probability of it being cost-effective when the decision-maker is unwilling to pay anything additional for an extra point increase in the GAF) is 69.3%. This exceeds the 50% decision rule, which is consistent with maximising expected health gain from limited resources (Claxton, 1999). If the decision-maker is prepared to pay at least a £20 per point increase in the GAF, then the probability of the treatment programme being cost-effective increases to 70%. At a figure of £655 per point increase in the GAF, the probability rises to 90%.
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DISCUSSION |
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Global functioning and symptom outcomes
Specific benefits were found on global functioning and this was consistent
with findings at the end of the treatment phase (9 months). Average
improvement on GAF scores for the intervention group was 22.5%, compared with
no change for the control group. Advantages for negative symptoms also were
found for the experimental group at 18 months, consistent with those found at
the end of treatment, suggesting a potentially robust outcome for these
symptoms. Traditionally, carer interventions have emphasised increasing
patient functioning and it is possible that integrating this with individual
CBT had a specific impact on negative symptoms as carers were helped to
reinforce and assist with patients strategies to increase functioning.
However, the benefits found at 12 months for the experimental group for
positive symptoms were not maintained at the 18-month follow-up. This is
inconsistent with previous CBT trials where gains on positive symptoms
generally have been maintained (see
Pilling et al, 2002). However, this trial differed from previous CBT trials in that the treatment
integrated the positive symptom, carer and substance use approaches rather
than focusing on positive symptom management alone. It is possible that
positive symptoms in this group may need more prolonged intervention
strategies to increase generalisation over time. However, it is also likely
that the interaction between substance use and psychotic symptoms is an
important consideration.
Although the treatment programme paid particular attention to integrating CBT for psychosis and substance use interventions, further development work is needed to clarify the nature of the interaction between psychosis and substance use in order to develop more refined treatment approaches. Anecdotal accounts by clinicians when conducting therapy indicated that this group had extremely complex and systematised psychotic symptoms that were clearly exacerbated by substance misuse. It is possible that the interaction between substance use and positive symptoms produces a type of psychopathology that is unique to this patient group and confirms earlier observations that specialist treatments are required that are designed to tackle both substance use and symptom outcomes. Larger sample sizes and more understanding of the psychopathology surrounding this interaction are warranted.
Carer outcomes
Although there were trends towards better personal outcomes for the carers
in the experimental group, the integrated programme did not show statistical
superiority on these measures. High rates of expressed emotion and general
psychopathology in carers were observed, and more specific interventions may
be necessary to bring about carer change. It should be noted that the carer
intervention was relatively short and it is possible that a more intensive
intervention is necessary.
Economic outcomes
The economic outcome analysis revealed that the experimental intervention
was no more costly than routine treatment and that there was a high
probability of it being cost-effective despite the high intensity of therapist
contact. The control group had a much larger (although statistically
non-significant) number of in-patient days in hospital, which is likely to
have offset the higher therapy costs in the experimental group.
Limitations
There are a number of limitations to the study that merit discussion.
First, although based on catchment area, the sample size was small. However,
the characteristics of the sample suggest that they are similar to other
substance-misusing psychosis groups cited in the literature
(Mueser et al, 1992).
Second, our sample only included those patients who had at least 10 h of
contact with a carer. It is difficult to know whether these results would
generalise to patients living alone and without contact with their families.
Furthermore, it is uncertain whether the treatment would be less or more
effective when family stress is removed from the patients immediate
environment. It is possible that those patients who have maintained close
family contact may have less severe problems than those who have not
maintained contact. However, a comparison of the characteristics of our group
with a matched sample of patients with schizophrenia and substance use who did
not have significant carer contact showed that the groups did not differ on a
range of variables (including symptom and illness severity and substance use
variables), although they were significantly older than our sample
(Schofield et al,
2001). It is possible that this indicates that carer relationships
of those patients who have psychosis and substance use problems may
deteriorate over time and carer contact may become reduced. Third, the small
sample size may have led to some potentially clinically significant results
not reaching statistical significance. Finally, because the study design did
not control for the additional staff time allocated to the experimental group
we cannot conclude that the benefits attributed to therapy did not arise from
additional contact per se. Clearly, further trials are required to
identify the active and most important ingredients of successful therapy with
this challenging client group.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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Received for publication October 20, 2002. Revision received March 20, 2003. Accepted for publication April 9, 2003.
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