Trimbos Institute/Netherlands Institute of Mental Health and Addiction, Utrecht
Department of Clinical Psychology, Vrije Universiteit Amsterdam, and Trimbos Institute/Netherlands Institute of Mental Health and Addiction, Utrecht
Gelderse Roos Institute for Professionalizing, Renkum, The Netherlands
Correspondence: Godelief Willemse, Trimbos Institute, PO Box 725, 3500 AS Utrecht, The Netherlands. E-mail: gwillemse{at}trimbos.nl
Declaration of interest None. Funding detailed in Acknowledgements.
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Aims To examine the effects of minimal-contact psychotherapy in primary care patients with sub-threshold depression on the onset of major depression, on the reduction in depressive symptoms and on health-related quality of life.
Method We conducted a randomised trial in primary care, in which patients screened for sub-threshold depression were randomly assigned to minimal-contact psychotherapy (n=107) or to usual care (n=109).
Results One year after baseline, the incidence of major depressive disorder was found to be significantly lower in the psychotherapy group (12%) than in those receiving usual care (18%). Small but significant effects were also found on depressive symptoms and on aspects of health-related quality of life.
Conclusions Primary care patients with sub-threshold depression can benefit from minimal-contact psychotherapy.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
METHOD |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Recruitment
Participants were recruited in two steps
(Fig. 1). In the first step, a
research assistant approached all patients who were waiting to see their
general practitioner (n=5276). The Instel screening questionnaire
(see Measures) was filled in during a brief face-to-face interview in a
separate room. From the 4525 patients who gave informed consent for screening,
3825 patients were screened. The other 700 patients were excluded on the basis
of age or criteria (a) and (b) above. In total, 1018 patients were assessed as
having a risk of sub-threshold depression. After office hours, the research
assistant consulted the general practitioner to determine if patients who
screened positive met exclusion criterion (c). In step two, screen-positive
patients who were willing to participate in the trial received a
computer-assisted telephone interview with the Composite International
Diagnostic Interview (CIDI; World Health
Organization, 1997). This resulted in 363 baseline interviews. The
main reasons for non-response (64%) were lack of interest, lack of time (47%)
and no telephone contact with the patient (14%, after at least ten calls at
different times and days). In addition, patients who met CIDI/DSMIV
diagnostic criteria for a mood disorder, social phobia, agoraphobia or panic
disorder in the past 12 months were excluded (n=95). Patients meeting
all inclusion criteria and who gave informed consent were randomised to
receive minimal-contact psychotherapy (n=107) or usual care
(n=109).
|
Interventions
The experimental intervention was minimal-contact
cognitivebehavioural therapy for depression, based on the Coping
with Depression course (Lewinsohn
et al, 1984) in its Dutch version
(Cuijpers, 2000). The main
component was a self-help manual with instructions on
cognitivebehavioural self-help in mood management skills. This
intervention has proved to be effective in reducing depressive symptoms in
several randomised clinical trials, both in group and individual format and in
minimal-contact format (Cuijpers,
1998). The manual also included registration exercises and
homework assignments. The intervention was augmented by a face-to-face
interview with a prevention specialist or a clinician from a community mental
health centre before the participant started reading the manual, and six short
telephone calls (maximum 15 min each). The first five telephone calls were
made once every 2 weeks, and the sixth call was made 2 months later. The
telephone contacts were not of a psychotherapeutic nature, but were to support
the participants in working through the manual.
Participants receiving the minimal-contact psychotherapy intervention were able to make use of all other types of health services during the intervention period, including those offered by their general practitioner. The comparison (control) intervention was usual care as routinely provided by general practitioners and other health service providers; the former were requested to base their treatments on the Dutch primary care guidelines for depression (Van Marwijk et al, 1994).
Study design
A power calculation indicated that 200 participants were needed per
condition to test the unidirectional hypothesis of a superior effect in the
treatment arm of the trial in a one-sided test at =0.05 and a power of
(1-ß)=0.80. This sample size would be enough to detect a difference in
the incidence rate of 10% or more (Hully
& Cummings, 1988).
We conducted a pragmatic randomised trial. Eligible participants (n=216) were randomised, with equal probability, to one of the trial arms. The randomisation was carried out centrally, using a blocked randomisation scheme stratified by general practice with the patient as the unit of randomisation, with blocks of four patients.
Data were collected at baseline and at 4 months, 12 months and 24 months after baseline. The 4-month follow-up was meant to collect data on patient satisfaction with the intervention. This paper focuses on the intervention effects at the 12-month follow-up assessment, as the 24-month follow-up data are not yet available. The trial protocol was endorsed by an independent medical ethics committee.
Measures
Because no (Dutch) screening instrument existed for sub-threshold
depression, we used the Instel screen
(Tiemens et al,
1995), which was adapted for this purpose. The Instel starts with
two core questions about loss of interest and feeling tense, with a negative
predictive value of 99% for either CIDI depressive disorder or generalised
anxiety disorder in primary care patients. A depression scale of six symptoms
follows after a positive answer on one of the two check questions. For
detecting sub-threshold depression, the positive predictive values for at
least one core symptom plus one, two or three current depressive symptoms were
16%, 61% and 56%, respectively. Negative predictive values were 88%, 91% and
90%, respectively.
The primary outcome of interest is the relative reduction in the incidence of DSMIV depressive disorder at the 12-month assessment, for which the CIDIAuto was used (version 2.1; World Health Organization, 1997) in its Dutch version (Ter Smitten et al, 1998). The CIDI is a standardised diagnostic interview for the assessment of mental disorders, developed by the World Health Organization. It was designed for use by trained lay interviewers. The CIDI is known to have high interrater and testretest reliability and its validity has been demonstrated to be adequate (Andrews & Peters, 1998; Wittchen, 1994). The interviews were conducted by telephone, as several findings provide qualified justification for this mode of assessing psychiatric disorder (Rohde et al, 1997; Evans et al, 2004). The interviewers had undergone a prior 3-day training course at the Dutch CIDI training centre. During the data collection, the results of the interviewers were continuously monitored. The interviewers were masked with respect to the randomisation status of the participants.
Secondary outcome measures were the number of depressive symptoms and subjective functioning. Depressive symptom level was ascertained with the Center for Epidemiological Studies Depression scale (CESD; Radloff, 1977) in its Dutch version (Bouma et al, 1995); this is a widely used self-report scale measuring the frequency of 20 depressive symptoms during the past week. The CESD generates a total score ranging from 0 to 60, with a higher score indicating more depressive symptoms. The Dutch translation has good reliability and validity (Bouma et al, 1995).
Subjective functioning was measured using the Dutch version of the RAND 36-item Health Survey (RAND36; RAND Health Science Program, 1992; Van der Zee & Sanderman, 1993), a generic self-report measure covering eight scales with respect to subjective functioning (see Table 1). Each scale represents a transformed score ranging from 0 to 100, with a higher score indicating better functioning. The Dutch version has good psychometric properties (Van der Zee & Sanderman, 1993).
|
The CESD data were collected by telephone at baseline and at 12-month and 24-month follow-up (together with the CIDI interview). The RAND36 data were collected at the same measurement points, but using paper and pencil questionnaires, which were sent by post to be completed at home and returned to the research team. The same procedure was followed for the collection of satisfaction data at the 4-month follow-up.
Analysis
At the 12-month follow-up assessment, 18% of the CIDI data were missing,
mainly owing to the participants lack of interest. Regression
imputation was used to tackle this problem. In the regression imputation
model, baseline scores of CESD, gender and age were used as predictors.
Since patients were recruited from 19 general practices some amount of
clustering had occurred. This clustering violates the assumption
of independence of observations, and may thus affect standard errors and
P values. So-called robust standard errors and correct
P values were obtained using the first-order Tailor series
linearisation method as implemented in Stata 7.0
(StataCorp, 2001). As there
was no significant difference between the two arms of the trial with regard to
social and demographic variables and baseline CESD and RAND36
scores, it was not necessary to control for confounders.
With regard to the central clinical end-point, we wanted to test the hypothesis that the incidence rate in the experimental group (IE) was lower than the rate in the control group (IC) after 1 year; in other words, we tested the hypothesis that the incidence rate ratio (IE/IC) was lower than 1. This was done by regressing the imputed CIDI/DSMIV depression status at 12 months on the treatment dummy in a Poisson regression while adjusting for the cluster effect.
For the secondary outcomes on continuous measurement scales (CESD) and RAND36), last observation carried forward was used to impute missing observations at follow-up. Students t test (corrected for the cluster effect) was used to test the hypothesis of superior treatment effects in the experimental arm.
All analyses were conducted according to the intention-to-treat principle. The evaluations of the effectiveness were conducted with one-tailed tests, because we were interested in the added value of the intervention therapy in the context of routine primary care. Unless otherwise specified, we used a 5% significance level (P<0.05). Furthermore, for the CESD the standardised effect size (d) was calculated by dividing the mean difference of the 12-month follow-up score of the control and intervention groups by the 12-month follow-up score standard deviation of the control group (Hedges & Olkin, 1985).
In order to compare completers and non-completers of the minimal-contact psychotherapy on the level of satisfaction with the intervention, the exact non-parametric MannWhitney U test was used.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Overall, 177 (82%) people participated in the 12-month follow-up interview. There was no significant difference in follow-up rates between the two trial groups. Completers and non-completers were compared by means of logistic regression analysis on socio-demographic factors and on CESD and RAND36 baseline scores. It was found that older people and those with more years of education were more likely to complete the 12-month follow-up interview (OR=1.04, 95% CI 1.011.08, P<0.05; OR=1.13, 95% CI 1.001.27, P<0.05, respectively). Moreover, men and people with subjectively worse mental health (RAND36) were less likely to complete the interview (OR=0.44, 95% CI 0.200.99, P<0.05; OR=0.97, 95% CI 0.951.00, P<0.05, respectively).
Effects on the incidence of depressive disorder
At 12 months, the incidence rate of depressive disorder was 0.12 (13/107)
for the minimal-contact psychotherapy condition and 0.18 (20/109) for the
usual care condition. The incidence rate ratio was 0.66 (95% CI
0.401.09) and significant in the one-sided test (P=0.049). The
number of people to be treated in order to avoid one case of major depression
was 16.
Effects on depressive symptoms and subjective functioning
The CESD and RAND36 scores at baseline and at 12 months are
presented in Table 2. Minimal
contact psychotherapy was found to have a significant effect on the
CESD and on two scales of the RAND36: physical
functioning and mental health. Six of the eight scales of
the RAND36 showed no significant difference. The standardised effect
size for the CESD was 0.18.
|
Acceptability of the intervention
Twenty-four (22%) of the 107 persons randomised to the psychotherapy
intervention group refused or failed to start the intervention and another 40
(37%) discontinued it, of whom 23 withdrew before the third telephone call
(see Fig. 1). The main reasons
for not starting were lack of time (29%), not feeling depressed (21%) and
motivational problems (17%). The main reasons for withdrawal were inability to
make telephone contact with the individual (23%), motivational problems (20%)
and participant not feeling depressed (20%).
Completer and non-completer groups were compared by logistic regression analysis on socio-demographic factors and on CESD and RAND36 baseline scores. It was found that men were less likely to complete the intervention than women (OR=0.26, 95% CI 0.100.69, P<0.01). Furthermore, those who did not complete perceived themselves as having significantly better mental health (RAND36 score) at baseline compared with those who did complete (OR=0.96, 95% CI 0.930.99, P<0.05).
The 4-month follow-up self-report questionnaire gave information about the satisfaction with the psychotherapy intervention (response rate 70%, n=75). In general, participants were satisfied or very satisfied about the coaching from the community mental health centre, the telephone calls (number, length, interval between calls), the homework (difficulty, relevance) and the content of the self-help book. However, participants who discontinued the intervention were significantly less satisfied than those who completed the intervention or who were still working through the intervention at the time of completion of the questionnaire. This was true for the coaching from the community mental health centre (U=201.50, P<0.05) and for the experienced relevance of the homework (U=157.50, P<0.05). Also, on several items regarding the perceived effects of the psychotherapy, those who discontinued had scores that were significantly more negative.
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Reduction of incidence of major depression
The incidence of major depression among participants in the experimental
condition (12%) was reduced by a third compared with the control condition
(18%). This is an important finding. Two other trials have found positive and
significant effects of cognitivebehavioural interventions on the
incidence of major depressive disorder among adolescents with depressive
symptoms (Clarke et al,
1995,
2001). Until now, only one
study had examined the possibility of preventing major depression in primary
care patients with sub-threshold depression
(Muñoz et al,
1995), and this study had insufficient statistical power to find a
significant effect. Our trial is therefore the first to show that major
depressive disorder can be prevented with a minimal intervention in primary
care patients with sub-threshold depression.
Despite this positive finding, we need to address the question of whether we focused this intervention on the right population. An incidence rate of 18% is considerable, but it is questionable whether it is sufficient to justify specific intervention. After all, more than 80% of those identified would not develop major depressive disorder within 1 year, and only 6% would benefit in terms of a prevented episode of major depression. Furthermore, almost 60% of the patients who were randomised to the experimental condition did not even start the intervention, or failed to finish it. These people perceived their mental health as significantly better at baseline compared with those completing the therapy, and one of the reasons given for withdrawal from the trial was that the person did not feel depressed. The natural course of the symptoms of these patients might have been so positive that an intervention was not necessary.
Effects on depressive symptoms
The effect of the experimental intervention on depressive symptoms was
significant, but relatively small. A reduction in depressive symptoms of 0.18
standard units is usually considered to be small
(Lipsey, 1990); psychotherapy
and pharmacological treatments for depression usually find reductions of 0.45
standard units or more (Lipsey &
Wilson, 1993) and this is also true for earlier studies of
minimal-contact psychotherapy (Cuijpers,
1997). There are several characteristics of our trial that may be
responsible for this small effect. First, trial participants were actively
recruited by screening, whereas most other trials have recruited people who
were seeking care for their depression, through announcements in papers and
other media, which might have resulted in a selection of more motivated
individuals. Second, most earlier trials of minimal-contact psychotherapy used
waiting-list comparison groups, whereas we used a usual care comparison group.
Third, previous research has concentrated mostly on people with major
depression rather than sub-threshold depression, as tested in this study.
Fourth, the small effects might be specific to the group of primary care
patients with generally good prognosis. Finally, it is also possible that the
small effects are in part caused by the fairly low participation rates in the
psychotherapy condition.
Acceptability and suitability of the intervention
None of the previous trials examining the effects of preventive
interventions on the incidence of new cases of depression has made use of
minimal-contact psychotherapy. This can be defined as a psychological therapy
in which the patient takes home a standardised psychological treatment manual
and works through it more or less independently, with only minimal support
from professionals. In a meta-analysis of six randomised trials of
minimal-contact psychotherapy for depression, it was found that the effects in
people with depressive symptoms are large and comparable with the effects of
traditional psychotherapy and antidepressive medication
(Cuijpers, 1997). This form of
therapy is also an interesting intervention for sub-threshold depression in
primary care, as it is brief and non-intrusive, and does not require much time
or specific skills from the doctor. Because it can be assumed that
sub-threshold depression does not justify full psychiatric treatment for a
major psychiatric disorder, a minimal intervention aimed at preventing the
onset of a depressive disorder seems adequate. The participants in our study
who started the intervention and completed a considerable part of it assessed
it as positive and helpful. In a systematic review of eight studies examining
self-help treatments for anxiety and depressive disorders in primary care
(Bower et al, 2001),
it was concluded that most studies in this area did find some positive results
of these self-help treatments, but also that more research in this area is
necessary. Our study adds to the empirical evidence that self-help treatments
are beneficial for some patients, but also indicates that more research is
needed before this approach can be confidently recommended as an
evidence-based practice.
Offering this minimal intervention to a much more selective patient population might increase the effectiveness as well as the efficiency of the intervention. For instance, in a recent trial a preventive intervention was offered to people who not only had sub-threshold depression but also belonged to a high-risk group adolescent children of depressed parents (Clarke et al, 2001). In this study the incidence of depression dropped from 29% to 9%. Another possibility for selection is to offer the intervention on a stepped-care base by starting with a short waiting time to exclude patients who recover quickly, because watchful waiting in itself can be an effective strategy (Barrett et al, 2001). Finally, open recruitment strategies should be used in order to reach motivated individuals.
Final remarks
Depression is one of the most important causes of disability, and is
expected to be the second leading cause of disability worldwide in 2020
(Murray & Lopez, 1996).
Reducing the burden of depression is possible, as is shown by the study
described here. Perhaps of equal importance is the opportunity to offer a
simple self-help treatment, which can be effective while consuming only small
amounts of health care resources. The further development and research of
preventive interventions in this area constitute a major challenge for
prevention science.
![]() |
Clinical Implications and Limitations |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
LIMITATIONS
![]() |
ACKNOWLEDGMENTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Andrews, G. & Peters, L. (1998) The psychometric properties of the Composite International Diagnostic Interview. Social Psychiatry and Psychiatric Epidemiology, 33, 80-88.[CrossRef][Medline]
Barrett, J. E., Williams, J. W., Oxman, T. E., et al (2001) Treatment of dysthymia and minor depression in primary care: a randomized trial in patients aged 18 to 59 years. Journal of Family Practice, 50, 405 -412.[Medline]
Bouma, J., Ranchor, A. V., Sanderman, R., et al (1995) Assessment of Depressive Symptoms with the CESD. Manual (in Dutch). Groningen: Noordelijk Centrum voor Gezondheidsvraagstukken/Rijksuniversiteit Groningen.
Bower, P., Richards, D. & Lovell, K. (2001) The clinical and cost-effectiveness of self-help treatments for anxiety and depressive disorders in primary care: a systematic review. British Journal of General Practice, 51, 838 -845.[Medline]
Broadhead, W. E., Blazer, D. G., George, L. K., et al (1990) Depression, disability days, and days lost from work in a prospective epidemiological survey. JAMA, 264, 2524 -2528.[Abstract]
Clarke, G. N., Hawkins, W., Murphy, M., et al (1995) Targeted prevention of unipolar depressive disorder in an at-risk sample of high school adolescents: a randomized trial of a group cognitive intervention. Journal of the American Academy of Child and Adolescent Psychiatry, 34, 312 -321.[Medline]
Clarke, G. N., Hornbrook, M., Lynch, F., et al
(2001) A randomized trial of a group cognitive intervention
for preventing depression in adolescent offspring of depressed parents.
Archives of General Psychiatry,
58, 1127
-1134.
Cuijpers, P. (1997) Bibliotherapy in unipolar depression: a meta-analysis. Journal of Behavior Therapy and Experimental Psychiatry, 28, 139 -147.[CrossRef][Medline]
Cuijpers, P. (1998) A psycho-educational psycho-educational approach to the treatment of depression: a meta-analysis of Lewinsohns Coping with Depression course. Behaviour Therapy, 29, 521 -533.
Cuijpers, P. (2000) The Coping with Depression Course (in Dutch). Utrecht/Baarn: Trimbos Institute/Intro.
Cuijpers, P., De Graaf, R. & Van Dorsselaer, S. (2004) Minor depression: risk profiles, functional disability, health care use and risk of developing major depression. Journal of Affective Disorders, 79, 71-79.[CrossRef][Medline]
Eaton, W. W., Badawi, M. & Melton, B. (1995) Prodromes and precursors: epidemiological data for primary prevention of disorders with slow onset. American Journal of Psychiatry, 152, 967 -972.[Abstract]
Evans, M., Kessler, D., Lewis, G., et al (2004) Assessing mental health in primary care research using standardized scales: can it be carried out over the telephone? telephone? Psychological Medicine, 34, 157 -162.[CrossRef][Medline]
Fairhurst, K. & Dowrick, C. (1996) Problems with recruitment in a randomised controlled trial of counselling in general practice: causes and implications. Journal of Health Services and Research Policy, 1, 77 -80.
Hedges, L. V. & Olkin, I. (1985) Statistical Methods for Meta-analysis Meta-analysis. Orlando, FL: Academic Press.
Horwarth, E., Johnson, J., Klerman, G. L., et al (1992) Depressive symptoms as relative and attributable risk factors for first-onset major depression. Archives of General Psychiatry, 49, 817 -823.[Abstract]
Hully, B. & Cummings, S. R. (1988) Designing Clinical Research: An Epidemiological Approach. Baltimore, MD: Williams & Wilkins.
Lewinsohn, P. M., Antonucci, D. O., Breckenridge, J. S., et al (1984) The Coping with Depression Course. Eugene, OR: Castalia.
Lipsey, M. W. (1990) Design Sensitivity: Statistical Power for Experimental Research. Newbury Park, CA: Sage.
Lipsey, M. W. & Wilson, D. B. (1993) The efficacy of psychological, educational, and behavioral treatment. Confirmation from meta-analysis. American Psychologist, 48, 1181 -1209.[CrossRef][Medline]
Muñoz, R. F., Ying, Y., Bernal, G., et al (1995) Prevention of depression with primary care patients: a randomized controlled trial. American Journal of Community Psychology, 23, 199 -222.[Medline]
Murray, C. J. & Lopez, A. D. (1996) The Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability, Injuries and Risk Factors in 1990 and Projected to 2020. Cambridge, MA: Harvard University Press.
Radloff, L. S. (1977) The CESD scale: a self-report depression scale for research in the general population. Applied Psychological Measurement, 1, 385-401.
RAND Health Science Program (1992) RAND 36-Item Health Survey 1.0. Manual. Santa Monica, Monica, CA: RAND.
Rohde, P., Lewinsohn, P. M. & Seely, J. S.
(1997) Comparability of telephone and face-to-face interviews
in assessing axis I and II disorders. American Journal of
Psychiatry, 154, 1593
-1598.
StataCorp (2001) Stata Statistical Software, Release 7.0. College Station, TX: StataPress.
Ter Smitten, M. H., Smeets, R. M. W. & Van den Brink, W. (1998) Composite International Diagnostic Interview (CIDI), Version 2.1, 12-months (in Dutch). Amsterdam/Geneva: World Health Organization.
Tiemens, B. G., Ormel, J., Brink, R. H. S., van den, et al (1995) Signalering van depressie en gegeneraliseerde angst in de huisartsenpraktijk. De ontwikkeling van een screeningsinstrument. Tijdschrift voor Sociale Gezondheidszorg, 73, 520 -527.
Van der Zee, K. I. & Sanderman, R. (1993) Assessment of General Health with the RAND36. Manual (in Dutch) . Groningen: Noordelijk Centrum voor Gezondheidsvraagstukken/Rijksuniversiteit Groningen.
Van Marwijk, H. W. J., Grundmeijer, H. G. L. M., Brueren, M. M., et al (1994) Dutch general practitioner society Guidelines on Depression (in Dutch). Huisarts en Wetenschap, 37, 482 -490.
Van Schaik, D. J. F., Van Marwijk, H. W. J., Van der Windt, D. A. W. M., et al (2002) Effectiveness of psychotherapy for depressive disorder in primary care. A systematic review (in Dutch). Tijdschrift voor Psychiatrie, 44, 609 -619.
Wagner, H. R., Burns, B. J., Broadhead, W. E., et al (2000) Minor depression in family practice: functional morbidity, co-morbidity, service utilization and outcomes. Psychological Medicine, 30, 1377 -1390.[CrossRef][Medline]
Wells, K. B., Burnam, A., Rogers, W., et al (1992) The course of depression in adult outpatients. Archives of General Psychiatry, 49, 788 -794.[Abstract]
Wittchen, H.-U. (1994) Reliability and validity studies of the WHO-Composite International Diagnostic Interview (CIDI): a critical review. Journal of Psychiatric Research, 28, 57-84.[CrossRef][Medline]
World Health Organization (1997) Composite International Diagnostic Interview (CIDI), Version 2.1, 12-months. Geneva: WHO.
Received for publication October 24, 2003. Revision received April 16, 2004. Accepted for publication June 26, 2004.