Computer Therapy for the Anxiety and Depressive Disorders Is Effective, Acceptable and Practical Health Care: A Meta-Analysis

Abstract

Depression and anxiety disorders are common and treatable with cognitive behavior therapy (CBT), but access to this therapy is limited.
Review evidence that computerized CBT for the anxiety and depressive disorders is acceptable to patients and effective in the short and longer term.
Systematic reviews and data bases were searched for randomized controlled trials of computerized cognitive behavior therapy versus a treatment or control condition in people who met diagnostic criteria for major depression, panic disorder, social phobia or generalized anxiety disorder. Number randomized, superiority of treatment versus control (Hedges g) on primary outcome measure, risk of bias, length of follow up, patient adherence and satisfaction were extracted.
22 studies of comparisons with a control group were identified. The mean effect size superiority was 0.88 (NNT 2.13), and the benefit was evident across all four disorders. Improvement from computerized CBT was maintained for a median of 26 weeks follow-up. Acceptability, as indicated by adherence and satisfaction, was good. Research probity was good and bias risk low. Effect sizes were non-significantly higher in comparisons with waitlist than with active treatment control conditions. Five studies comparing computerized CBT with traditional face-to-face CBT were identified, and both modes of treatment appeared equally beneficial.
Computerized CBT for anxiety and depressive disorders, especially via the internet, has the capacity to provide effective acceptable and practical health care for those who might otherwise remain untreated.
Australian New Zealand Clinical Trials Registry ACTRN12610000030077.

Full text

Computer Therapy for the Anxiety and Depressive
Disorders Is Effective, Acceptable and Practical Health
Care: A Meta-Analysis
Gavin Andrews
1
*, Pim Cuijpers
2
, Michelle G. Craske
3
, Peter McEvoy
4
, Nickolai Titov
5
1School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia, 2Department of Clinical Psychology, Vrije Universiteit Amsterdam,
Amsterdam, The Netherlands, 3Department of Psychology, University of California Los Angeles, Los Angeles, California, United States of America, 4Centre for Clinical
Interventions, Perth, Western Australia, Australia, 5School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia
Abstract
Background:
Depression and anxiety disorders are common and treatable with cognitive behavior therapy (CBT), but access
to this therapy is limited.
Objective:
Review evidence that computerized CBT for the anxiety and depressive disorders is acceptable to patients and
effective in the short and longer term.
Method:
Systematic reviews and data bases were searched for randomized controlled trials of computerized cognitive
behavior therapy versus a treatment or control condition in people who met diagnostic criteria for major depression, panic
disorder, social phobia or generalized anxiety disorder. Number randomized, superiority of treatment versus control (Hedges
g) on primary outcome measure, risk of bias, length of follow up, patient adherence and satisfaction were extracted.
Principal Findings:
22 studies of comparisons with a control group were identified. The mean effect size superiority was
0.88 (NNT 2.13), and the benefit was evident across all four disorders. Improvement from computerized CBT was maintained
for a median of 26 weeks follow-up. Acceptability, as indicated by adherence and satisfaction, was good. Research probity
was good and bias risk low. Effect sizes were non-significantly higher in comparisons with waitlist than with active
treatment control conditions. Five studies comparing computerized CBT with traditional face-to-face CBT were identified,
and both modes of treatment appeared equally beneficial.
Conclusions:
Computerized CBT for anxiety and depressive disorders, especially via the internet, has the capacity to provide
effective acceptable and practical health care for those who might otherwise remain untreated.
Trial Registration:
Australian New Zealand Clinical Trials Registry ACTRN12610000030077
Citation: Andrews G, Cuijpers P, Craske MG, McEvoy P, Titov N (2010) Computer Therapy for the Anxiety and Depressive Disorders Is Effective, Acceptable and
Practical Health Care: A Meta-Analysis. PLoS ONE 5(10): e13196. doi:10.1371/journal.pone.0013196
Editor: Bernhard T. Baune, James Cook University, Australia
Received June 18, 2010; Accepted September 7, 2010; Published October 13, 2010
Copyright: ß2010 Andrews et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: GA, NT, PM, MC hold a grant for research on Internet Treatment from the Australian National Health and Medical Research Council registration
#630560. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: gavina@unsw.edu.au
Introduction
Anxiety disorders and major depressive disorders are common,
costly and debilitating [1,2]. Remarkably, less than half the people
with these disorders see a physician and only a quarter receive
appropriate treatment [3]. Effective treatments for these disorders
exist (i.e., selective serotonin reuptake inhibitors (SSRIs) and
cognitive behavior therapy (CBT) [4,5]. However, the public
health impact of these remedies is limited for a number of reasons.
Specifically, these disorders often are unrecognized [3,6], the
efficacy of SSRIs may be limited to very severe cases [7], CBT is
not widely available, in part because of insufficient numbers of
adequately trained clinicians [8], and patients do not or cannot
adhere to the costs and demands of face-to-face CBT treatment.
Almost one third of individuals attending an anxiety disorders
clinic did not start treatment [9], and attrition from randomized
controlled trials for anxiety and depression can reach 50% [10].
Internet and computer-based delivery formats could improve
access to CBT. There have been two recent meta-analyses of
internet-based and other computerized psychological treatments
for depression and anxiety states [11,12]. They included studies of
participants at risk, with sub-threshold symptoms, or with DSM
disorders. In anxiety states, the effect size superiority over control
conditions was large (23 studies, Cohen’s d = 1.1), and in
depressive states the effect size was moderate (12 studies,
d = 0.41). Two transdiagnostic programs included in these meta-
analyses, one aimed at panic and phobias – Fearfighter [13] – and
the other aimed at depression and anxiety states - Beating the
Blues [14] – were sufficiently powerful to be recommended for
routine use in the UK National Health Service [15].
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Recent research on computerized CBT delivered over the
internet (iCBT) or by computer in the clinic (cCBT) has
emphasized programs in which a predetermined syllabus presents
the principles and methods of CBT in a series of lessons, usually
with homework assignments and supplementary information. The
majority of newer programs are designed for individual anxiety or
depressive disorders. Computerized CBT can be self-guided,
supported by reminders from a non-clinical technician or practice
nurse, or guided by a clinician who makes telephone calls, sends
emails or posts comments on a private forum. The major
advantages of iCBT are accessibility and convenience for both
patients and clinicians, but equally important is that treatment
fidelity in both iCBT and cCBT is guaranteed by the
computerized delivery. If these treatments are to become part of
health care we need to know if such programs benefit patients who
meet criteria for anxiety or depressive disorders in the short- and
long-term, and if they are acceptable to such patients.
Rationale
We restricted the present review to studies designed as
randomized controlled trials of computerized CBT for participants
who met diagnostic criteria for either major depressive disorder,
social phobia, panic disorder with or without agoraphobia, or
generalized anxiety disorder (GAD). Computerized CBT was
required to be the major intervention that was compared to treatment
as usual, or to control conditions such as placebo or waitlist. We
confined the analysis of outcome to self report measures of the
principal characteristic of each disorder; to the magnitude and
stability of the outcome; and to the acceptability of computer
therapy as estimated from the level of adherence to the course and
the satisfaction upon completion.
Method
This review was registered (www.ANZCTR.org.au/ACTRN
12610000030077.aspx). All English language randomized con-
trolled trials of iCBT or cCBT that used participants who met
DSM criteria (established by structured diagnostic interview) for
either major depression, social phobia, panic disorder or GAD,
and that compared iCBT or cCBT with treatment as usual,
placebo or waitlist control groups, were included. All papers
analysed were either published or in press and the investigators
had copies of all final manuscripts.
Information sources
The search strategy followed that of the previous meta-analyses
[11,12] that used a database of studies on psychological treatment
[16] (www.psychotherapyrcts.org) and other general data bases to
include RCTs of computer-aided psychotherapy that were
published after the cut off dates for previous meta-analyses (from
March 2008 for anxiety disorders and January 2009 for
depression). The search was conducted on the 31
st
of December
2009. A total of 2670 abstracts were examined from the following
databases: PubMed (N = 308), Cochrane Database of Systematic
Reviews and Register of Controlled Trials (N = 719), Cinahl
(N = 88), PsychINFO (N = 78), Medline (N = 171), Social Sciences
Citation Index (N = 1155), and Embase (N = 155). We identified
abstracts by combining terms indicative of psychological treatment
and depression, anxiety, and anxiety disorders (both MeSH terms
and text words). In addition, these terms were paired with the
terms ‘internet or computer or online’ to identify papers relating to
internet or computer treatment in particular. Reference lists for all
identified reviews and meta-analyses of computer-aided psycho-
therapy, as well as those of included studies, for the time period of
interest were also examined. Finally, we wrote to researchers to
identify any unpublished studies meeting the inclusion criteria.
Study selection
All studies of adults with the relevant diagnoses that randomized
subjects to computerized CBT versus treatment as usual or control
condition were included. We additionally examined studies in
which computerised CBT was compared with face to face CBT.
Items extracted in each study were as follows: Number of subjects
randomized; basic results (details of treatment condition, details of
control group, significant differences in outcome, Hedges g and
number needed to treat (NNT), adequacy of bias minimization
scored 0 = complete minimization, 5 = no minimization (ade-
quacy of sequence generation, allocation concealment, adequate
blinding, missing data addressed, no selective reporting [17]);
follow-up duration and stability, acceptability to participants
(percent adherent to the full course, percent satisfied). These
acceptability and bias ratings were independently conducted by
two researchers, with differences resolved following discussion.
Meta-analysis
We followed a described method [12, p197–198]. In brief, we
calculated the effect size (Hedges’ g) indicating the difference
between the two conditions at post-test, as the difference between
the mean of the treatment condition and the mean of the control
condition, divided by the pooled standard deviation and adjusted
for small sample bias [18]. We only used instruments that related
to the principal measure of the disorder to generate a mean effect
size. Because the effect size is not easy to interpret from a clinical
point of view, we also calculated the NNT by transforming the
effect sizes based on Z scores using the formulae provided by
Kraemer and Kupfer [19]. The NNT is defined as the number of
patients one would expect to treat to have one more successful
outcome.
The effect sizes for each study were pooled according to the
random effects model, and differences between subgroups of
studies tested using the mixed effects model. As indicators of
heterogeneity of pooled effect sizes, we calculated I
2
, which
indicates the heterogeneity in percentages, and we tested whether
the level of heterogeneity was significant using the Q statistic.
Small study bias was tested by inspecting the funnel plot on the
primary outcome measures (effects on depression or anxiety at
post-test) and by a trim-and-fill procedure [20], which yields an
estimate of the pooled ES after taking bias into account. All
analyses were conducted using the computer program Compre-
hensive Meta-Analysis (version 2.2.021) [21].
Results
The previous meta-analyses [11,12] were taken as having been
comprehensive for the period covered by their search strategy.
Nine studies included in those meta-analyses met the new
inclusion criteria, (focus on one of the four specified diagnoses,
iCBT or cCBT the principal treatment). Thirteen additional
studies were identified making 22 studies in all. Minimization of
research bias was assessed [17]. All studies reported data using the
intention to treat method and all used self report measures of the main
outcome thereby obviating the need for blinding. Three studies only
met these basic criteria, 13 studies also met the method of sequence
generation or allocation concealment criteria and six studies satisfied all 5
criteria.
Results of the meta-analysis of the 22 studies [22–43] are
displayed in Table 1: grouped by diagnosis, listing author and date
of publication, N randomized, effect size of intervention compared
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to control condition (Hedges g), NNT, risk of bias; length of follow-
up; and adherence and patient satisfaction as a proxy for
acceptability. Summary data are in Table 2 and a funnel plot of
studies ranked by disorder shows the confidence limits around the
effect sizes for each study (Figure 1).The overall effect size
superiority of computerized CBT over control group across all
four disorders was 0.88 and the confidence limits did not include
zero (p,0.001). Similar results were obtained for major depression
(g =0.78, 95% CI 0.59–0.96), social phobia (g = 0.92, 95% CI
0.74–1.09), panic disorder (g = 0.83, 95% CI 0.45–1.21) and GAD
(g =1.12, 95%CI 0.76–1.47). Heterogeneity was non-significant
for each disorder and for all studies together. There was a small,
non-significant indication for small sample bias (adjusted effect size
g = 0.80). Although the effect size for studies using a waitlist
control group (g = 0.94; 95% CI: 0.81–1.07) was somewhat higher
than for treatment as usual and other control groups (g = 0.75;
95% CI: 0.51–0.98), this difference was not significant (p.0.1).
Fourteen of the 22 studies reported follow-up data that range
from 4 to 52 weeks post-treatment (median 26 weeks), and in none
was there evidence of relapse. Adherence and satisfaction are
indicators of acceptability of computerised CBT to patients. All
studies measured one or both. Adherence was good, and a median
of 80% of people who began these programs completed all lessons
(range 48%–100%). Ten of the 23 studies provided data on patient
satisfaction and a median of 86% (range 70%–100%) of patients
reported that they were satisfied or very satisfied.
There were two studies [25,27], in which computerized CBT
was also compared to face-to-face CBT for depression and three
Table 1. Selected characteristics and results of randomized controlled studies examining the effects computerized and internet-
based cognitive behaviour therapy for adult depression and anxiety disorders.
Study Conditions N g NNT Bias Risk F-U Adhere/Satisf
MAJOR DEPRESSION
Andersson, 2005
22
iCBT +therapist support .waitlist +discussion group 75 0.87 2.16 0 26w 63/-
Kessler, 2009
23
iCBT +therapist support .TAU by GP 297 0.61 2.99 0 16w 73/-
Perini, 2009
24
iCBT +therapist support .waitlist 48 0.56 3.25 1 - 74/82
Selmi 1990
25
cCBT .waitlist 36 1.26 1.59 2 9w 100/-
Titov 2010
26
iCBT +therapist support .waitlist 141 0.99 1.94 1 - 70/87
Wright 2005
27
cCBT +therapist support .waitlist 45 1.10 1.77 1 26w 87/-
PANIC DISORDER
Carlbring, 2001
28
iCBT .waitlist 41 0.99 1.94 1 - 80/85
Carlbring, 2006
29
iCBT .waitlist 60 1.13 1.74 0 39w 80/97
Klein, 2001
30
iCBT .Self-monitoring control 23 0.39 4.59 2 - 90/-
Klein, 2006
31
iCBT .Information control 55 1.49 1.41 1 13w 90/-
Richards, 2006
32
iCBT .Information control 32 0.74 2.50 0 13w 82/-
Wims 2010
33
iCBT +therapist support .waitlist 59 0.28 6.41 1 4w 79/-
SOCIAL PHOBIA
Andersson, 2006
34
iCBT .waitlist 64 0.76 2.44 0 52w 56/-
Berger et al. 2009
35
iCBT .waitlist 52 0.64 2.86 1 - 90/85
Botella et al. 2009
36
iCBT .waitlist 52 1.07 1.82 2 52w 48/-
Carlbring, 2007
37
iCBT .waitlist 57 1.07 1.82 1 52w 93/-
Furmark et al 2009
38
iCBT +therapist support .waitlist 120 0.67 2.75 0 52w 97/70
Titov, 2008 I
39
iCBT +therapist support .waitlist 105 0.94 2.02 1 26w 78/100
Titov, 2008 II
40
iCBT +therapist support .waitlist 88 1.18 1.68 1 26w 81/100
Titov, 2008 III
41
iCBT +therapist support .waitlist 98 1.02 1.89 1 - 77/-
GAD
Titov 2009
42
iCBT +therapist support .waitlist 48 1.08 1.81 1 - 75/85
Robinson 2010
43
iCBT +therapist support .waitlist 150 1.13 1.74 1 - 74/87
N, number randomized; g, Hedges g; NNT number needed to treat; Bias risk (0 =no risk, 5 = high risk) inadequacy of sequence generation, no allocation concealment,
inadequate blinding, missing data not addressed, selective reporting; F-U, follow-up in weeks; Adhere/satisfaction, percent adhering to whole course/percent satisfied
with course; iCBT, CBT over the internet; cCBT, CBT over computer in clinic; GAD, Generalized Anxiety Disorder.
doi:10.1371/journal.pone.0013196.t001
Table 2. Summary results of meta-analyses examining the
effects of internet- and computerized CBT for depression and
anxiety disorders.
Disorder N g 95% CI Z
I
2
NNT
MDD 6 0.78 0.59–0.96 8.20 *** 0 2.39
Social phobia 8 0.92 0.74–1.09 10.28 *** 0 2.07
Panic 6 0.83 0.45–1.21 4.27 *** 49.77 2.26
GAD 2 1.12 0.76–1.47 6.19 *** 0 1.75
All disorders 22 0.88 0.76–0.99 15.04 *** 7.84 2.15
doi:10.1371/journal.pone.0013196.t002
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comparison trials, not included in the main meta-analysis as there
was no control group, in which the comparison between
computerised CBT and face to face CBT was in patients with
depression or panic disorder [44–46] (total number of patients in
the five studies was 567; 300 in the computerized and 267 in the
face-to-face conditions). The effect size indicating the difference
between computerized-treatments and face-to-face treatments was
non-significant g = 0.09 in favour of computerized treatments
(95% CI: 20.34,17), with zero heterogeneity. In the computer
condition therapist time was reduced compared to face-to-face
therapy for depression by 50% [27] and 79% [44], and in panic
disorder by 35% [46] and 70% [45]. Treatment satisfaction was
reported as good in both computerised and face-to-face treatment
groups [27,45,46].
Discussion
Twenty two RCTs of computerised CBT for major depression,
social phobia, panic disorder or generalized anxiety disorder
showed superiority in outcome over control groups. The effect
sizes are substantial, and the results indicate both short term and
long term benefits. Furthermore, patients adhered to and were
satisfied with computerised CBT, despite the significantly reduced
amount of contact with the clinician. Thus, computerised CBT is
an efficacious and acceptable treatment, and by increasing
convenience and reducing clinician time that would otherwise be
required by face-to-face treatment, it offers increased access to
treatment for those suffering from anxiety and depression.
The results come from 9 different groups working indepen-
dently in 7 different countries. Similar results were obtained for
each disorder and heterogeneity was non-significant for each
disorder and for all studies together. It is as though there is a core
set of CBT skills that is of benefit in the internalising disorders
included in this analysis.
Most patients had been recruited as volunteers, largely after
media publicity, but a minority were referred by their clinician.
This raises the question, ‘are these patients comparable to patients
who seek face-to-face treatment?’ In a large study (n = 774),
internet patients with one of these four disorders were as severe
when assessed by symptom, distress and disability measures as
those attending a face-to-face clinic, and both groups were
significantly more severe than cases identified in an epidemiolog-
ical survey [47]. Another index of severity is treatment history.
Three studies reported this. In one study of iCBT for depression in
a primary care setting, three quarters of patients had a history of
previous episodes [23]. The chronicity was similar in two iCBT
studies for depression in community volunteers. In the first [24]
70% had sought prior help and 51% were currently taking
medication for their depression. In the second study [26] help
seeking and medication rates were comparable and 72% said their
onset of depression was before the age of 21, 78% said they had
had more than 5 episodes and 78% said that they had had no
remission in the last 2 years. Thus, it appears that participants in
these trials resemble people who attend regular clinics. There were
few data on treatment history in the studies of anxiety disorders.
The mean effect size, indicating the superiority of the comput-
erized intervention over the control group, was 0.88, NNT 2.15. The
most common control group was waitlist, with treatment for them
delayed until the intervention group had completed treatment.
Placebo or active treatment control groups are preferable, but are
Figure 1. Effect sizes of Computerised CBT versus control conditions at post-test.
doi:10.1371/journal.pone.0013196.g001
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difficult to arrange when there is no face to face contact with the
participants. Interventions compared to waitlist controls have shown
increased effect sizes compared to interventions compared to the
treatment as usual studies [12] and the null finding in the present
meta-analysis may be due to insufficient power. There were no
studies comparing computerised CBT and medication. Five studies
compared internet therapy directly with face-to-face CBT for
depression or panic disorder, and while all found strong pre-post
treatment effects, none found differences between the two modes of
delivery. We conclude that computerized CBT, with clinician or
technician assistance which can be as brief as one hour per patient,
can work as well as face-to-face CBT.
Adherence to computerized CBT was good; in the median
study, 80% of individuals who began these programs completed all
stages. This rate of completion suggests that computerized CBT
was well accepted by participants. The programs contained
between five and nine ‘lessons’. Conceivably, some participants
who do not complete all the lessons may have gained all they need
from the program. More research is needed regarding the tailoring
of computerized programs to the needs of individuals. Ten of the
22 studies provided data on patient satisfaction; in the median
study 86% of patients were satisfied or very satisfied with the
computerized CBT program. Participants noted the advantages of
computerized therapy, including convenience (such as completion
of the program in the evening when there are no competing
demands), ability to proceed at one’s own pace to master the
material, low cost and privacy. We conclude that computerised
CBT is acceptable to patients.
There is a need for more extensive follow-up assessment as only
14 of the 22 studies provided follow-up data, at a median 26 weeks
(range 4–52). As with face-to-face CBT [5], the benefits lasted and
no significant relapse was reported.
The majority of studies identified measures of distress, disability,
quality of life, or work force participation as secondary outcome
measures. While changes in these secondary outcome measures
were not as large as in the primary outcome measures, they were
significant and demonstrate that internet treatment has the
capacity to change health status not merely reduce specific
symptoms. One study pooled data from three RCTs of social
phobia and showed significant improvements in comorbid
symptoms of depression and generalized anxiety even though
the treatment was focused solely on the social phobia [48].
The benefits described are substantial yet the content of the
programs is relatively simple and the therapist or technician
contact brief. For example in the Andersson [22] study (g = 0.87),
the treatment group had access to five weekly text ‘lessons’ about
recovering from depression – behavioural activation, cognitive
restructuring, sleep and physical health, and relapse prevention
and future goals. This raises an issue of whether we presently
conceptualise the nature of these four disorders correctly, either as
related to temperament [2] or to neurotransmitter abnormalities
[49] neither of which could be expected to yield to relatively brief
sessions of skills based teaching about controlling worrying
thoughts and confronting feared situations. The mechanism by
which these programs produce benefit needs to be explored.
In sum, the 22 identified computerized CBT programs
generated a large effect size superiority over control groups with
maintenance of gains at follow-up and good patient adherence and
satisfaction. As the programs become more sophisticated, the
clinician or technician time required seems to be decreasing to the
order of 10 minutes per week per patient [26,43,50].
Is it possible to integrate these internet services with existing
mental health services so that people who do not recover with
internet therapy can, in a stepped care design, receive face to face
care? We now, it seems, are beginning to know enough about the
efficacy, applicability and potential cost savings from the internet
programs for people with anxiety and depressive disorders to begin
to integrate these internet services with existing mental health
services.
Author Contributions
Conceived and designed the experiments: GA PC MGC PM NT.
Performed the experiments: PC PM. Analyzed the data: GA PC MGC
PM NT. Contributed reagents/materials/analysis tools: NT. Wrote the
paper: GA PC MGC PM NT.
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