Social Psychiatry Section
Centre for the Economics of Mental Health
Department of Biostatistics & Computing, Institute of Psychiatry, London
Psychotherapy Department, Bethlem & Maudsley NHS Trust, London
The Family Institute, Cardiff
Department of Psychology, Royal Holloway College, Egham
Royal South Hants Hospital, Southampton
Correspondence: Professor Julian Leff, Head of Social Psychiatry Section, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF
Declaration of interest Funding from the Medical Research Council.
See editorial, pp. 93-94,
this issue.
This article has been corrected post-publication, in accordance with the printed corrigendum September 2000, vol. 177, p. 284.
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ABSTRACT |
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Aims To compare the relative efficacy and cost of couple therapy and antidepressant drugs for the treatment and maintenance of people with depression living with a critical partner.
Method A randomised controlled trial of antidepressant drugs v. couple therapy. The subjects were 77 people meeting criteria for depression living with a critical partner.
Results Drop-outs were 56.8% from drug treatment and 15% from couple therapy. Subjects' depression improved in both groups, but couple therapy showed a significant advantage, according to the Beck Depression Inventory, both at the end of treatment and after a second year off treatment. Adding the costs of the interventions to the costs of services used showed there was no appreciable difference between the two treatments.
Conclusions For this group couple therapy is much more acceptable than antidepressant drugs and is at least as efficacious, if not more so, both in the treatment and maintenance phases. It is no more expensive overall.
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INTRODUCTION |
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METHOD |
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Subjects
Subjects were recruited in different ways. The majority came through
professional contacts, including general practitioners in north and south
London, and the Maudsley Hospital out-patient service and emergency clinic. A
minority contacted us in response to advertisements in local newspapers.
Subjects had to be under the age of 65 and had to have lived with a
heterosexual partner for at least 1 year. They also needed to reach a level of
caseness (Index of Definition level 5 or above), receive a
primary classification of depression on the Present State Examination - Catego
System (Wing et al,
1974) and achieve a score on the Hamilton Depression Rating Scale
(Hamilton, 1960) of at least
14. These criteria define a major depressive episode. The partner had to be
rated as expressing at least two critical comments during the Camberwell
Family Interview (Vaughn & Leff,
1976a).
Patients were excluded if they showed any psychotic features, or suffered from bipolar illness, organic brain syndrome, severe suicidal tendencies, primary substance abuse, learning difficulties, or contraindications (such as pregnancy) for antidepressants. Those who had during the preceding 3 months experienced an adequate course of either of the treatments offered in the trial were also excluded. The criteria for adequacy were 6 weeks of an antidepressant at a therapeutic dosage, or six sessions of couple therapy.
A power calculation based on the relapse rates in the naturalistic studies of critical partners and the course of depression indicated that for a significance level of P < 0.05 and a power of 80%, a sample size of 40 in each group was required. The research team made contact with 290 individuals, of whom 196 were excluded because they did not have a stable relationship or would not accept random allocation to treatment. Of the remaining 94 people, six rejected the possibility of receiving anti-depressants. This left 88 subjects and their partners who met our criteria, who were randomised to one of the trial groups, using a computer-generated random number table and sealed envelopes. As part of the randomisation procedure, subjects were stratified according to whether or not they had a significant history of depression, defined as a current episode of depression lasting 6 months or more or a previous treated episode in the last 3 years.
Treatments
Initially we had intended to compare three treatments for depression:
antidepressants, couple therapy and cognitive therapy. We anticipated
recruiting three subjects per month, but the rate actually achieved was two
per month, and the drop-out rate from the cognitive therapy arm was so high (8
out of 11) that this treatment option was soon deleted from the trial. Hence
we present here the results for the 77 subjects who received antidepressants
or couple therapy. We did not include a group of subjects who were assigned to
no treatment, as this was considered unethical, given the well-established
efficacy of anti-depressants for major depressive episodes.
Antidepressant regime
The pharmacotherapy was the responsibility of D.D., who selected a regime
to represent the best available clinical practice, while ensuring compliance.
The initial medication was a tricyclic anti-depressant, desipramine, provided
there was no contraindication. The dose was gradually increased over a few
weeks, titrating it against side-effects and symptom reduction. To monitor
compliance independently of the patient's report, serum levels were checked at
4 weeks, 8 weeks, 6 months and 1 year. If, despite taking desipramine for a
full 6 weeks in doses that achieved therapeutic serum levels (125 µg/ml),
there was no response, or intolerable side-effects developed, a second-line
anti-depressant was substituted: if agitation was prominent, trazodone was
prescribed, whereas if the patient showed retardation, fluvoxamine was given.
Once an effective dose had been achieved and symptoms remitted, the patient
was continued on this dose for 4 months, following which the dose was
gradually reduced to between 1/2 and 2/3 of the peak dose. Patients were
maintained on this dose for the rest of the first year. Alongside medication,
during the first two sessions an educational programme about depression and
antidepressants was given to the patient and their partner, to maximise
compliance. The sessions lasted 20-30 minutes, those who completed the course
received between 12 and 20 sessions. After 1 year the antidepressant was
tailed off over 2 weeks, although two patients chose to remain on medication,
and two others relapsed as soon as it was stopped, necessitating a
resumption.
Couple therapy
Two senior family and couple therapists were responsible for developing the
form of treatment used in this trial. In their model the patients' depressive
symptoms are conceptualised in interactional terms. Close relationships are
regarded both as influencing, and being influenced by, the patient and his/her
symptoms. Systemic couple therapy aims to help the patient and partner to gain
new perspectives on the presenting problems, to attach different meanings to
the depressive types of behaviour and to experiment with new ways of relating
to each other. During a pilot phase, the therapists constructed a manual, and
modified it through experience with six couples who met the criteria for the
trial but were not randomly allocated to treatment. During this phase the
therapists attempted to design specific interventions aimed at directly
reducing criticism by the partner. However, the techniques used seemed to have
little effect on the patient's depressive symptoms and were therefore not
included in the final version of the protocol.
The manual (Jones & Asen, 1999) specifies in detail the techniques to be employed, such as observation and enactment of couple issues, attempts to interrupt problematic cycles of behaviour to shift negative attributions, and setting of tasks to develop less problematic ways of interacting. The manual describes three distinct phases of therapy in which various specific interventions are used, while allowing for enough flexibility to avoid the therapy becoming a strait-jacket for everyone concerned. The protocol allowed for 12-20 sessions, lasting around 50 minutes each.
Assessments
The initial assessment of the patient included a full psychiatric history,
the Present State Examination (PSE), the Hamilton Rating Scale for Depression
(HRSD), and the Beck Depression Inventory (BDI)
(Beck et al, 1961).
The partner was assessed by means of the Camberwell Family Interview (CFI),
while both patient and partner completed the Dyadic Adjustment Scale
(Spanier, 1976) to measure the
quality of their relationship. Following the completion of treatment, and at
the end of a second year without treatment, these assessments were repeated
for patient and partner by researchers who were blind to the treatment group
of the subjects. Changes in the CFI and the Dyadic Adjustment Scale will be
presented in another paper dealing with the mechanisms of action of the
treatments.
Economic analysis
The cost of couple therapy was calculated on the basis of the number (and
average duration) of sessions and the unit cost per hour of direct research
therapist's contact time. All prescribed antidepressants (and associated blood
tests) over the course of the study were recorded and costed, so that drug
therapy costs could be estimated. Service utilisation data were collected
using a variant of the Client Service Receipt Inventory (CSRI;
Beecham & Knapp, 1992),
which covered a range of key health and social care services (in-, out-, and
day patient hospital services, day care and contacts with a general
practitioner, community psychiatric nurse, social worker and counsellor). Unit
costs were attached to these data, and aggregated to give a total service cost
estimate for each subject in the study. Unit cost figures were calculated to
represent long-run marginal opportunity costs, and were drawn from national
estimates, adjusted for London as necessary
(Netten & Dennett, 1996).
Informal caregiver support by family members or others, and the indirect
consequences of depression (lost employment), were not costed in this study.
Analysis of cost differences between the two groups focused on the mean
(rather than the median) as the measure of direct policy interest, using a
non-parametric bootstrap for the estimation of 95% confidence intervals, owing
to the positively skewed distribution observed for service cost variables
(Barber & Thompson,
1998).
Statistical analysis
Each outcome variable provided data at three time points: baseline, 1-year
and 2-year follow-up. Various methods of analysis have been proposed for such
longitudinal data (Everitt,
1985,
1998;
Diggle et al, 1994).
Because of the loss of data when patients dropped out, it was decided to use
the likelihood approach, originally described by Schluchter
(1988) and implemented in the
BMDP statistical package as BMPD5V. This method allows for drop-outs, and
produces valid parameter estimates and standard errors as long as the
drop-outs are not informative (Everitt,
1998). Even when the drop-outs are informative, the likelihood
method will produce a less biased analysis than commonly used alternatives,
such as analysing only those who complete the course, or replacing missing
values with the last available measurement (last observation carried forward)
(Diggle, 1998). The analysis
included all patients for whom data were available for at least one of the
1-year and 2-year follow-ups in addition to the baseline assessment. The
1-year follow-up sample comprised only those who had completed the treatment,
while the 2-year follow-up sample also included some patients who had dropped
out of treatment prematurely.
We used the BDI and the HRSD as indicators of outcome but excluded the PSE, as it is primarily a diagnostic instrument and is not sensitive to incremental changes over time.
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RESULTS |
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Patients' progress through the trial is shown in a CONSORT diagram (see Fig. 1).
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Drop-outs
Of the 37 patients randomly allocated to the drug treatment, nine dropped
out before their first treatment visit, and another 12 subsequently. Three of
these patients were withdrawn from the trial by the pharmacotherapist, two
because they developed mania (an exclusion category for the trial) and one on
account of intolerable side-effects. Only two people objected to having blood
tests: one had severe needle phobia and the other refused tests, but both
continued with the treatment. All the tests showed that patients had
antidepressant levels within the therapeutic range. Of the 40 patients
randomly allocated to couple therapy, three dropped out before any treatment,
and a further three subsequently. The difference in total drop-out rate
between drug treatment (56.8%) and couple therapy (15.0%) is 41.8% (95% CI
31.8-51.8) and is highly significant (2=14.72, d.f.=1,
P<0.001).
Drop-outs were compared with those who completed treatment as regards several variables, in order to identify what might determine failure to complete treatment. No differences were found between the two groups regarding gender, Dyadic Adjustment Score, partner's critical comments or HRSD score. However, the drop-outs were significantly younger than the completers (34.3 v. 41.8, t=3.30, d.f.=75, P<0.002), and had higher BDI scores (29.4 v. 25.2, t=2.99, d.f.=75, P<0.004). The assessments at the 1-year follow-up were only conducted on subjects who completed treatment. However, at the 2-year follow-up, a small financial inducement persuaded a number of drop-outs, particularly those in the drug group, to return for assessment.
Effects of treatment
The statistical analysis was conducted on an intention-to-treat basis, and
any data available from drop-outs were included. The likelihood approach was
used to fit a variety of models for the mean profiles of the BDI outcome
variable. The main effects of treatment group and time, and the interaction of
treatment group and time, were considered. In addition, the initial value of
the BDI was introduced as a covariate, along with age and a small number of
additional covariates such as gender and history of depression. Only treatment
group was found to be significant, with an average difference in BDI scores of
6.4 (95% CI 1.62-11.54). In the absence of a significant group x time
interaction, this implies that from initial assessment to the 1-year
follow-up, the mean BDI score in the couple therapy group falls to between
1.62 and 11.54 points lower than the corresponding mean in the medication
group. This difference is maintained from the 1-year time point until the
2-year follow-up. Figure 2
shows the mean scores and standard errors of the means over the three time
points.
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The same analysis was applied to the HRSD scores, and produced a different result, namely that a significant improvement had occurred after treatment for both groups, which was sustained during the year without treatment, but that there was no significant advantage for couple therapy over medication.
Economic component
The collection of data regarding use of services, necessary for the
economic evaluation of the alternative therapy strategies, did not form part
of the original battery of instruments, so that these data were missing for
initial recruits to the trial (27 cases). Drop-outs during the treatment phase
who failed to return for the 2-year follow-up, loss of contact over the
follow-up phase with those who had completed treatment, and non-consent at
both assessment points also contributed to a considerable reduction in the
sample available for economic analysis.
Table 2 gives the costs of therapy and service use over the treatment and follow-up phases of the study. It should be noted that the drug treatment costs include the cost of the blood tests (a mean of £3.73 per month), which would not be done routinely. The mean monthly cost of couple therapy was £106 (s.d.=23), compared with a treatment cost of £48 (s.d.=18) for the drug group. This significantly greater cost of treatment (£58, 95% CI 45-72) is offset by a reduction in the costs of hospital and community services (a mean of £53 per month less in the couple therapy group, 95% CI 130 to 10). As evidenced by the low median values and large standard deviations, however, these service costs varied markedly, and mean differences were not statistically significant. The combined mean of therapy and service use is similar for the two groups (£5 higher in the couple therapy group; 95% CI 76 to 71).
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The costs of service use were also monitored over the follow-up period of the study, and included costs incurred by treatment-phase drop-outs who agreed to be interviewed. Mean service costs were higher in the drug group (£67, s.d. 122) than in the couple therapy group (£43, s.d. 60), but this difference was not statistically significant (£24, 95% CI 83 to 25), again due to the skewed nature of the data (median costs per month for both groups were only £16). It is noticeable (but not tabulated here) that the cost of hospital service use over the follow-up period for the ten cases who did not engage in either form of therapy (£111, s.d. 170) was three times as great as that for the 38 cases who did engage in therapy (£38, s.d. 52).
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DISCUSSION |
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Differences between the outcome assessments
The analysis demonstrated the superiority of couple therapy over
antidepressant drugs, both for the treatment phase and for the maintenance
phase, as judged by the BDI scores. By contrast, the HRSD scores did not
discriminate between the improvements in the two treatment groups. This may be
because the two scales have a different proportion of cognitive-affective
items: 67% of the BDI and 29% of the HRSD. Furthermore, the BDI has 4-point
scales for each item, whereas the HRSD requires yes/no replies. Senra &
Polaino (1998) consider that
discrepancies between the HRSD and BDI as regards the degree of improvement
brought about by treatment are essentially due to differences in scale
content. Comparison with previous controlled trials of marital therapy is not
easy, since in three of the five studies the other treatment was cognitive
therapy, a modality which was dropped from our trial. Of the other two
studies, Waring et al
(1988) included too few
subjects in each cell to draw valid conclusions. The numbers were reasonably
large in the trial by Friedman
(1975) but that continued for
only 12 weeks. It was a four-cell design, with random assignment to
amitriptyline or placebo, and to weekly marital therapy or to minimal contact.
Neither amitriptyline nor marital therapy showed any advantage over the
control treatment in alleviating depression. However, patients who received
marital therapy rated the marriage as better at follow-up than those in the
minimal contact group. In the absence of any directly comparable study, our
finding of an apparent advantage of couple therapy over antidepressants needs
to be replicated in further trials before being accepted as proven.
Comparative costs of the treatments
The addition of a costing component to the study illustrated that the cost
of couple therapy was approximately double that of a conventional
antidepressants. The observed difference in treatment cost appears to be
moderated by a reduced use of other services. What distinguishes the two
groups more than any difference in total direct cost is the constitution of
the costs (couple therapy: 81% treatment, 19% service use; drug group: 38%
treatment, 62% service use). Alongside the improvement in BDI scores observed
for the couple therapy, this provides encouraging evidence for the
cost-effectiveness of this intervention. However, the post-design addition of
the service utilisation schedule, plus subsequent non-completion and
drop-outs, reduced the size of the sample for whom costs could be estimated to
a small one only. Taken in conjunction with the highly positively skewed
distribution of service costs, this leaves us much less capable of commenting
on the findings with any statistical confidence. Also, only direct costs of
care and support were included: the wider economic consequences of depression,
including the costs associated with work disability, were not fully
considered.
Are the results generalisable?
To what extent can these findings be applied to the general population of
patients with depression? Clearly they cannot be extrapolated beyond those
living with a heterosexual partner. One selection criterion for our sample was
that the partner had to make more than one critical comment on the CFI. In
fact, only a handful of patients was excluded on this basis. Not only do
patients with depression living with a partner greatly prefer couple therapy
to antidepressant drugs: it is also at least as efficacious, and may be
superior, both in the treatment and the maintenance phases. The economic
analysis has to be treated with caution because of missing data, but does
suggest that the higher cost of couple therapy is compensated for by less
expenditure on other services used by the patients. We consider that our
findings constitute a strong argument for training primary care personnel in
the skills of couple therapy.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Received for publication November 13, 1998. Revision received February 4, 2000. Accepted for publication February 10, 2000.
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