Efficacy of Treatment for Somatoform Disorders: A Review of Randomized Controlled Trials

Efficacy of Treatment
for Somatoform Disorders:
Kurt Kroenke, M.D.
A Review of Randomized
Controlled Trials
Objective: To review the evidence from randomized clinical trials (RCTs) that have focused on the treatment of patients with Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) somatoform disorders. Although somatoform disorders are among the most common mental disorders presenting in the general medical setting,
the strength of evidence for specific treatments has not been well synthesized. Methods: MEDLINE search of articles
published in English from 1966 to 2006, using the following search terms: randomized clinical trial, somatoform disorders, somatization disorder, undifferentiated somatoform disorder, hypochrondriasis, conversion disorder, pain disorder, and body dysmorphic disorder. Results: A total of 34 RCTs involving 3922 patients were included. Two thirds of
the studies involved somatization disorder (n ⫽ 4 studies) and lower threshold variants, such as abridged somatization
disorder (n ⫽ 9) and medically unexplained symptoms (n ⫽ 10). Cognitive behavioral therapy (CBT) was effective in
most studies (11 of 13), as were antidepressants in a small number (4 of 5) of studies. RCTs examining a variety of
other treatments showed benefit in half (8 of 16) of the studies, the most consistent evidence existing for a consultation
letter to the primary care physician. Effective treatments have been established for all somatoform disorders except conversion disorder (1 of 3 studies showing benefit) and pain disorder (no studies reported). Conclusion: CBT is the best
established treatment for a variety of somatoform disorders, with some benefit also demonstrated for a consultation
letter to the primary care physician. Preliminary but not yet conclusive evidence exists for antidepressants.
(Reprinted with permission from Psychosomatic Medicine 2007; 69:881– 888)
INTRODUCTION
Somatoform disorders are among the most prevalent mental disorders seen in the general medical
setting, present in 10% to 15% of primary care
patients (1– 4). The functional impairment associated with somatoform disorders is comparable with
that seen in depressive and anxiety disorders (5, 6).
Moreover, clinically significant somatization leads
to excessive health care use, costing the US health
care system an estimated $100 billion annually (7).
Also, somatoform disorders are among the most
frustrating mental disorders for clinicians to manage and also result in high levels of patient dissatisfaction (5, 8 –10). Finally, there is greater skepticism regarding the treatability of somatoform
disorders compared with the confidence practitioners have regarding the treatment of depression and
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anxiety. It is likely that if evidence-based treatments
existed and were more uniformly applied, the adverse consequences of somatoform disorders, including disability, costs, and dissatisfaction would
be reduced.
There have been several evidence-based reviews
of psychological treatments for somatic symptoms
and functional somatic syndromes (11–15). However, the overlap between these symptom-based
general medical disorders and somatoform disorders remains controversial. Therefore, a critical review of the literature was undertaken to determine
which treatments are efficacious for somatoform
disorders and to ascertain the strength of evidence for particular treatments. The purpose is
both to guide current practice as well as to identify gaps in the evidence to inform future treatment research.
THE JOURNAL OF LIFELONG LEARNING IN PSYCHIATRY
KROENKE
METHODS
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RESULTS
SOMATOFORM
DISORDERS STUDIED IN THE
RANDOMIZED CLINICAL TRIALS
A total of 34 randomized clinical trials (RCTs)
involving 3922 patients were included (Table 1).
Two thirds of the studies involved somatization
disorder (SD) (n ⫽ 4 studies) (20 –23) and lower
threshold variants, such as abridged versions of SD
(n ⫽ 9) (24 –32) and medically unexplained symptoms (n ⫽ 10) (33– 42). There were five studies of
hypochondriasis (43– 47), three of conversion disorder (48 –50), and three of body dysmorphic disorder (BDD) (51–53). Three of the trials included
patients with undifferentiated somatoform disorder (USD) but did not report the results separately
for USD (30 –32). Also, most or all of the patients
in the nine studies of abridged versions of SD and
the ten studies of medically unexplained symptoms
would likely meet the criteria for USD. Finally,
although there are a large number of RCTs in the
literature focused on patients with specific pain
conditions or chronic pain in general, there were no
studies of Diagnostic and Statistical Manual of
Mental Disorders, 4th Edition (DSM-IV) pain disorder per se.
TREATMENTS
STUDIED IN THE
RCTS
INFLUENTIAL
PUBLICATIONS
A MEDLINE search of articles published in English from 1966 to 2006 was conducted, using the
following search terms: randomized clinical trial,
somatoform disorders, somatization disorder, undifferentiated somatoform disorder, hypochrondriasis, conversion disorder, pain disorder, and
body dysmorphic disorder.
Potential studies were also identified from bibliographies of retrieved articles, as well as several recent reviews of selected treatments (12, 14, 16, 17).
Prepost studies (i.e., where outcomes were assessed
in a single group of patients before and after an
intervention) were excluded. Also excluded were
studies that focused on specific symptoms (e.g.,
back pain, headache) or functional somatic syndromes (e.g., irritable bowel syndrome, fibromyalgia).
Data were abstracted on the following key variables: somatoform disorder category, sample size,
type of intervention, number of and duration of
sessions, type of control group, duration of followup, outcomes evaluated, and treatment effect. The
following types of patient-centered outcomes were
evaluated: a) symptoms (i.e., the study’s main measure of somatic symptom count and/or severity); b)
functional status (i.e., the study’s main measure of
functional impairment or quality of life); and c)
psychological (i.e., either a domain specific to the
disorder, such as hypochondriacal or body dysmorphic beliefs and behaviors, or a generic measure of
depression, anxiety, or psychological distress). For
each trial, these three outcomes were assessed as
positive (outcome was better in the treatment
group than the control group), equivocal (there was
a trend favoring the treatment group but the group
difference was not statistically significant), negative
(the groups did not differ), or not assessed. Secondary variables for which data were abstracted include
patient demographics (age, gender, educational
level, race), and country as well as type of clinic in
which the study was conducted.
A standard meta-analytic approach to aggregate
the reported data on efficacy was not possible because of the small number of trials for a given intervention within broad treatment classes; substantial
differences in the definition and types of reported
outcomes; and considerable variation in the reporting of statistical details, such as exact p values and
standard deviations. Moreover, many studies neither stated what the primary outcome was nor prespecified the sample size needed to adequately test
for a primary outcome. Therefore, similar to several
previous literature syntheses of mental health interventions across multiple conditions (12, 18), a
vote-counting approach (19) was used to classify
each trial as positive or negative. Any trial that reported statistically significant improvement in at
least one of the three patient-centered outcomes
was operationally defined as a positive trial.
Cognitive behavioral therapy (CBT) was the
treatment studied in 13 trials, antidepressants in 5,
and other treatments in 16 (Table 2). Twelve of the
16 trials involving other treatments were conducted
in patients with SD and its lower threshold variants
and evaluated a psychiatric consultation letter (n ⫽
4) to the patient’s primary care physician (PCP),
training PCPs how to better manage somatizing
patients (n ⫽ 3), non-CBT psychotherapy (n ⫽ 2),
a multicomponent nurse care management intervention (n ⫽ 1), aerobic exercise (n ⫽ 1), and writing disclosure (n ⫽ 1). There were studies of hypnosis (n ⫽ 2) and paradoxical intention (n ⫽ 1) in
conversion disorder and explanatory therapy (n ⫽
1) in hypochrondriasis.
The median number of subjects and range per
study by type of treatment are shown in Table 2.
There were a few studies with very small samples
(⬍40 subjects), and the several largest studies fo-
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415
416
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173
61
79
50
82
228
98
200
Hellman et al.a 1990 (33)
Speckens et al. 1995 (34)
Lidbeck 1997 (35)
McLeod et al.a 1997 (36)
Peters et al. 2002 (37)
Kolk et al. 2004 (38)
Smith et al. 2006 (39)
112
Kroenke et al. 2006 (29)
Muller et al. 2004 (32)
111
Dickinson et al. 2003 (28)
200
127
Larisch et al. 2004 (27)
149
137
Schilte et al. 2001 (26)
Volz et al. 2000 (30)
68
Volz et al. 2002 (31)
56
Sumathipala et al. 2000 (25)
70
Kashner et al. 1995 (22)
Smith et al. 1995 (24)
73
Rost et al. 1994 (21)
84
38
Smith et al. 1986 (20)
Allen et al. 2006 (23)
na
Disorder(s)
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MUS
MUS
MUS
MUS
MUS
MUS
MUS
SD (67) USD (30)
SAD (90)
SD (108) USD (7)
SAD (38)
SD, USD, SAD
MSD
MSD
ASD or greater
ASD
ASD
ASD
SD
SD
SD
SD
Control
Usual care
Usual care
Psychotherapy, ⱕ12
(1 hr)
Bundled (CBT and/or
antidepressant)
Stretching, 20
(1 hr)
Wait list
Wait list
Usual care
Stress
management
Placebo
Placebo
Placebo
Placebo
Usual care
PCP trained in
psycho-social
care
Usual care
Usual care
Usual care
Consult letter to
PCP
Consult letter to
PCP
Usual care
Usual care
Exercise, 20 (1 hr)
CBT-group, 6
CBT-relaxation therapy, 8
(3 hr)
CBT, 6 to 16 (1 hr)
CBT-group, 6 (1.5 hr)
St. John’s wort
St. John’s wort
Opipramol
Venlafaxine
Consult letter to PCP
PCP training in
reattribution (12 hr)
Writing disclosure, 2
(1.5 hrs)
CBT, 6 (1/2 hr)
Consult letter to PCP
CBT, 10 (1 hr)
Psychotherapy-group, 8
(2 hr)
Consult letter to PCP
Consult letter to PCP
Treatment,
No. Sessions (hours)
12
12
6
6
6
12
6
1/12
1/12
1/12
3
24
6
24
3
24
15
12
12
18
Follow-up
(mo)
⫺
⫹
⫹
⫹
2 HC; 2 medications
⫹
⫺
⫺
⫹
⫹
Response difference ⫽ 16%
⫹
(Continued)
Low power—imbalanced groups (only
18 controls)
Active instead of usual care
comparator. Both groups improved
ES ⫽ 0.43
2 Utilization; ES ⫽ 0.38 to 0.88
Response difference ⫽ 25%;
excluded major depression
⫺
⫺
⫺
⫺
⫹
⫹
⫺
Response difference ⫽ 18%; ES ⫽
0.54 and 36 (6 and 12 months)
⫹
⫹
ES ⬍ St. John’s wort trials
Independent of depression
improvement
⫹
⫹
⫹
Pain improved, but not total somatic
symptom score
5.5 1 PCS score (ES ⫽ 0.48);
change similar for SD and ASD
Used active instead of usual care
comparator. Patients in each group
got mean of 4.5 sessions
No effect on utilization
⫹
⫾
⫺
⫹
⫹
⫺
⫺
⫹
⫾
⫺
⫺
⫺
2 Utilization
2 Costs
⫹
⫹
Comments
Response difference ⫽ 35%; 2
costs
2 Costs
2 Costs
2 Costs
⫹
⫺
⫺
⫺
Functional Psychologic
⫹
⫹
Symptoms
Outcomesb
Summary of 34 Randomized Clinical Trials Testing Treatments for Somatoform Disorders
Reference
Table 1.
KROENKE
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187
45
44
30
54
Barsky et al. 2004 (47)
Moene et al. 2002 (48)
Moene et al. 2003 (49)
Ataoglu et al. 2003 (50)
Rosen et al. 1995 (51)
Hypnosis, 10 (1 hr)
Inpatient treatment for 12
weeks plus hypnosis,
8 (1 hr)
CBT, 6 (1.5 hr)
CT or exposure Rx, 12
(1 hr)
Explanatory, 8 (1/2 hr)
CT or stress
management, 17 (1 hr)
CBT, 16
BDD
BDD
BDD
Fluoxetine
CBT, 12
CBT with exposure rx, 8
(2 hr)
CD
Paradoxical intention
(pseudoseizures)
twice daily for 3
weeks as inpatient
CD (motor)
CD (motor)
HC
HC
HC
HC
HC
Usual care
Placebo
Wait list
Wait list
Diazepam
Wait list
Inpatient treatment
for 12 weeks
Usual care
Wait list
Wait list
Wait list
Wait list
Wait list
3
3
6
1.5
6
8
12
7
6
12
7
6
6
12
Follow-up
(mo)
2 HC cognitions/behaviors; 2
utilization
⫹
⫹
⫹
⫾
2 Obsessive-compulsive BDD
beliefs and behaviors
2 Obsessive-compulsive BDD
beliefs and behaviors
⫹
⫹
2 Obsessive-compulsive BDD
beliefs and behaviors
⫹
1/15 versus 6/15 seizures
(p ⫽ .08)
2 Motor signs using video
rating scale immediately
post treatment but not
assessed at follow-up
⫺
2 HC cognitions/behaviors; no
effect on HC somatic sx
⫾
⫹
Hypnosis provided no added
benefit to inpatient
treatment
⫹
2 HC cognitions/behaviors; CT
⫽ stress management in
efficacy
⫹
2 HC cognitions/behaviors; CT
⫽ exposure in efficacy
2 HC cognitions/behaviors
⫹
⫹
2 Utilization; 2 medications;
mixed somatization results
2 Utilization
Comments
⫺
⫺
⫺
Psychologic
⫺
⫹
⫾
⫹
⫺
⫺
⫺
Functional
Symptoms
Outcomesb
SD ⫽ somatization disorder; ASD ⫽ abridged somatization disorder; MSD ⫽ multisomatoform disorder; MUS ⫽ medically unexplained symptoms; SAD ⫽ somatoform autonomic dysfunction; HC ⫽ hypochondriasis; BDD ⫽
body dysmorphic disorder; CBT ⫽ cognitive-behavioral therapy; PCP ⫽ primary care physician; ES ⫽ effect size (mean group difference ⫼ SD); USD ⫽ undifferentiated somatoform disorder; CD ⫽ conversion disorder; GP ⫽
general practitioner; CT ⫽ cognitive therapy; Sx ⫽ symptoms; Rx ⫽ therapy.
a
Drop-outs are not included in n if not included in the analysis of the original paper.
b
⫹ ⫽ treatment group was better than control group on this outcome; ⫾ ⫽ there was a trend favoring the treatment group but the difference was not statistically significant; ⫺ ⫽ the groups did not differ on this outcome.
67
78
Visser et al. 2001 (46)
Phillips et al. 2002 (53)
20
Fava et al. 2000 (45)
19
48
Clark et al. 1998 (44)
Veale et al. 1996 (52)
32
Warwick et al. 1996 (43)
GP training (8 hr)
CBT-group, 1 (3.5 hr)
MUS ⱖ2
MUS ⱖ2
295
140
Rief et al. 2006 (41)
Usual care
Control
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Martin et al. 2007 (42)
GP training in
reattribution (25 hr)
MUS
667
Rosendal et al. 2007 (40)
Disorder(s)
Treatment, No.
Sessions (hours)
na
Continued
Reference
Table 1.
KROENKE
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Selected Characteristics of Trials by Type of Treatment for
Somatoform Disorder
Table 2.
Cognitive-Behavioral
Therapy
Characteristic of Trial
Number of trials
Antidepressants
Other
Therapy
13
5
16
Median
68
149
86
Range
19–187
67–200
20–667
982
701
2239
⬍6 months
2
5
1
6–11 months
7
0
6
ⱖ12 months
4
0
9
Sample size, n subjects
Total (all trials)
Duration of follow-up, n trials
cused on general practitioner training, where patients enrolled were clustered within a modest
number of physcians, potentially diminishing the
study power. All five antidepressant trials had ⱕ3
months of follow-up, whereas the duration of follow-up tended to be longer in the studies of nonpharmacological interventions.
TREATMENT INTENSITY FOR INTERVENTION
GROUP AND TYPES OF CONTROL GROUPS
Data could be abstracted for 24 studies (Table 1)
on the number of sessions and total contact hours
provided for subjects in the intervention arm (it was
not relevant and therefore not provided for five antidepressant trials, four trials of a consultation letter
to the PCP, and one trial of a bundled CBT/antidepressant trial). The median number of sessions
was 8 (range ⫽ 1–30), and the median number of
total contact hours was 12 (range ⫽ 3–25). Subjects in the control arm were assigned to treatment
as usual in 12 trials, a wait list in 10, an active
comparator in 7, and placebo (all drug trials) in five.
The active comparator was a psychiatric consult
letter to the PCP in two trials, and stress management, stretching exercises, diazepam, psychiatric
inpatient treatment, or specialized PCP psychosocial training in one trial each.
SECONDARY
STUDY CHARACTERISTICS
Slightly over half (n ⫽ 18) of the trials reported
enrollment rates. In these trials, the median proportion of eligible subjects enrolled was 76% (range ⫽
30%–100%). In the seven CBT trials that reported
enrollment rates, the median was 81% (range ⫽
30%– 87%). All trials reported the proportion of
women, the median being 75% (range ⫽
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45%–100%). All trials also reported the average patient age, the median being 43 years (range of average
ages ⫽ 27.0 –50.6 years). Ten trials (all from the
United States) reported on race/ethnicity, with the
median proportion of minority subjects enrolled being 19% (range ⫽ 10%–37%). In the 16 trials that
reported educational status, the variable ways of reporting years of schooling made precise pooled estimates difficult. Nonetheless, the median educational
level achieved approximated a high school education.
Of the 34 trials, 13 were conducted in the United
States (20 –24, 28, 29, 33, 36, 39, 47, 51, 53), 6 in
Germany (27, 30 –32, 41, 42), 6 in the Netherlands (26, 34, 38, 46, 48, 49), 4 in the United
Kingdom (37, 43, 44, 52), and 1 each in Denmark
(40), Italy (45), Sri Lanka (25), Sweden (35), and
Turkey (50). The treatment was administered by a
mental health professional (MHP) in 22 trials, a
primary care provider in 9 trials (20, 21, 24, 27–29,
39 – 41), and other types of providers in 3 trials (26,
35, 37). Of the 22 trials involving an MHP-delivered intervention, 10 enrolled subjects solely or
predominantly from primary care (22, 23, 25, 33,
34, 36, 38, 42, 45, 47), and the MHPs were psychiatrists in 16 trials (22, 23, 25, 30 –32, 34, 43–
45, 47–50, 52, 53), psychologists in 4 trials (38, 42,
46, 51), and behavioral medicine specialists in 2
trials (33, 36). Finally, the vast majority of studies
were published in the past decade with 22 published since 2000, nine studies between 1995 and
1999, two studies between 1990 and 1994, and
only one study before 1990.
OUTCOMES
IN GENERAL
Outcomes of individual trials are summarized in
Table 1. Of the 20 studies assessing somatic symptom outcomes, 10 (50%) were positive trials
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KROENKE
whereas 4 were equivocal and 6 were negative. Of the
14 studies assessing functional status, 8 (57%) were
positive trials whereas 1 was equivocal and 5 were negative. Of the 32 studies assessing psychological distress, 18 (56%) were positive trials whereas 14 were
negative. Of the 10 trials in which somatic symptoms
improved, depression and/or psychological distress
also improved in 7 trials, did not improve in 2 trials,
and was not assessed in 1 trial. Improvement in the
primary outcome measure was independent of depression status or change in the six studies where this
was assessed (31, 32, 39, 44, 45, 53).
A secondary outcome highly relevant to somatoform disorders is health care use and/or costs, and 10
of the 11 studies assessing this outcome showed reduction in health care use (5 trials) or costs (5 trials).
OUTCOMES
BY TREATMENT TYPE
OUTCOMES
BY SOMATOFORM DISORDER
CATEGORY
SD and its lower threshold variants. CBT was
effective in five of seven trials, and antidepressants
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DISCUSSION
This literature synthesis allows one strong and
several tentative conclusions regarding the efficacy
of treatment for somatoform disorders. First, CBT
is consistently effective (11 of 13 trials) across a
spectrum of somatoform disorders including SD
and its lower threshold variants, hypochondriasis
and BDD. Second, a psychiatric consultation letter
to the primary care physician about strategies for
managing the somatizing patient seems to improve
physical functioning (three of four trials) and reduce costs, although surprisingly the effect on somatic symptoms themselves has not been reported.
Third, although there is preliminary evidence that
antidepressants may be beneficial, the degree to
which this is a general effect mediated through reduced depression and anxiety versus a specific effect
on somatic symptoms needs to be better ascertained. A variety of other treatments have been evaluated for which the results have been either negative or inconclusive.
All trials except three were published in the past
decade. This could be due to a number of factors
ranging from substantial changes in classification, a
paucity of interest in somatoform disorders, lack of
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PUBLICATIONS
Table 3 shows the proportion of positive trials by
major treatment category. A positive study was defined as one in which the treatment group fared better
than the control group on at least one of the three
patient-centered outcomes. The one treatment for
which there seems to be convincing evidence is CBT,
which proved beneficial for at least one outcome in 11
of 13 trials. Of the five trials examining antidepressants, four were positive (two trials of St. John’s wort
and one of opipramol for SD-spectrum disorders and
one trial of fluoxetine for BDD), whereas one was
equivocal for the primary outcome but positive for at
least one secondary patient-centered outcome (venlafaxine for SD-spectrum disorders). It should be
noted that all antidepressant trials specified a primary
outcome, whereas many nonpharmacological studies
did not specify a primary outcome but simply reported multiple outcomes.
Of the other treatments, only two were evaluated
in ⱖ1 or 2 studies. Three of the four trials examining the effectiveness of providing a simple psychiatric consultation letter to PCPs were positive; the
benefits were in terms of improved functional status (3 of 4 positive for this outcome) rather than
reduced psychological distress (0 of 4 positive). Somatic symptom outcomes were not assessed in any
of these four studies, although there were cost savings in all three studies that examined this outcome.
Only one of the three trials examining the effectiveness of providing specialized training to PCPs in
managing the somatizing patient proved positive.
in three of four trials. A psychiatric consultation
letter to the PCP was effective in three of four trials,
whereas providing specialized training to the PCP
was effective in only one of three trials. A multicomponent nurse-administered intervention, using
a type of CBT and antidepressants as indicated, was
beneficial in one trial, whereas one of two trials
using non-CBT psychotherapy was positive. Finally, one trial found aerobic exercise ineffective
(although an active comparator of muscle stretching was used in the control group), and emotional
disclosure through writing was ineffective in a single trial.
Hypochondriasis. CBT proved consistently effective (four of four trials involving a total of 345
patients). One pilot study of explanatory therapy in
20 patients was also positive. All five trials also
showed benefits in terms of hypochondriacal cognitions and behaviors.
Body Dysmorphic Disorder. CBT was effective
in two of two trials involving a total of 73 patients,
and fluoxetine was effective in a single trial involving 67 patients. All three trials also showed benefits
in terms of obsessive-compulsive BDD beliefs and
behaviors.
Conversion Disorder. There were only three
small studies of conversion disorder (two using
hypnosis and one using paradoxical intention), and
the results were inconclusive.
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KROENKE
Table 3.
Outcomes of 34 Randomized Clinical Trials for Somatoform Disorders
Cognitive-Behavioral
Therapy
Disorder
Antidepressants
Other
Therapy
Somatization disorder
1/1
2/3
Lower threshold somatization disorder
1/1
Medically unexplained symptoms
3/5
1/5
Hypochondriasis
4/4
1/1
3/4
Conversion disorder
3/4
1/3
Body dysmorphic disorder
Total
2/2
1/1
11/13
4/5
8/16
Positive trials/total trials.
clinical trial funding for these disorders, and the
fact that most somatizing patients present in primary care and fewer are referred to mental health
specialists than patients with other mental disorders. Although somatoform disorders are just as
common as depression and anxiety in primary care,
the number and quality of trials to inform our treatment of somatoform disorders are far less.
The literature reviewed has important limitations,
which in turn weaken the conclusions we can draw,
except for the likely efficacy of CBT. First, the heterogeneity of conditions, disease definitions, treatments, intervention type and intensity, outcomes, and
duration of follow-up precluded quantitative pooling
of study data. Thus, we had to resort to a crude votecounting approach of characterizing studies as positive
or negative, and a narrative synthesis rather than a
formal meta-analysis. Second, most trials measured
multiple outcomes and reported neither which outcome was primary nor a prespecified sample size.
Therefore, our operational definition of a positive trial
as needing to show benefit for only one of the three
patient-centered outcomes could overestimate treatment benefits because multiple outcomes were often
assessed and analyses were not typically adjusted for
multiple hypothesis testing. On the other hand, many
studies had small sample sizes meaning the differences
that were found had to be of at least a moderate magnitude to be statistically significant. Third, the comparison arm for most studies was a usual care, wait list,
or active comparator rather than placebo control.
Consequently, blinding of the patient was impossible
in many of these studies, and blinding of the outcome
assessment was often not specified.
Functional somatic syndromes (e.g., irritable
bowel syndrome, fibromyalgia, chronic fatigue syndrome) and individual chronic symptoms (e.g.,
headache, low back pain) were not the subject of
this review but exhibit considerable overlap with
somatoform disorders (54) as well as depression
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Summer 2009, Vol. VII, No. 3
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and anxiety (55). It is therefore notable that evidence-based reviews have established the efficacy of
both CBT and antidepressants for these somatic
conditions (11–15, 56). Additionally, it seems the
effect of CBT and antidepressants on somatic
symptoms is not entirely mediated through reduction of depression and psychological distress (11,
12). On the other hand, depression and anxiety
frequently co-occur in patients with functional somatic syndromes as well as somatoform disorders
(4, 57), and some studies have suggested that somatic symptoms may improve to a lesser degree
than emotional symptoms (58, 59).
Regarding type of treatment, the strongest and
most consistent evidence exists for CBT. In contrast, the number of antidepressant trials was small.
Of these five trials, four were positive for the prespecified primary outcome, whereas the other was
positive for one of the other patient-centered outcomes considered primary for this review. Compared with the nonpharmacological treatment
studies, antidepressants had on average larger patient samples, had a prespecified primary outcome,
and were placebo-controlled; the latter two factors
would tend to increase the likelihood of a negative
trial. On the other hand, antidepressant trials
tended to have shorter follow-up periods, leaving
unanswered questions about the persistence of benefits and the need for chronic therapy. Also, the
three antidepressant trials, which showed benefits
for SD-spectrum disorders, were all conducted in
Germany and used either St. John’s wort or opipramolol rather than antidepressants typically prescribed in the US. Much stronger evidence is
needed regarding the efficacy of pharmacotherapy,
including the magnitude and sustainability of its
benefits for somatic symptoms as well as its independent effect not mediated by improvement of
comorbid depression and anxiety.
Ironically, a psychiatric consultation letter pro-
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disorders and medically unexplained symptoms
among the most difficult conditions to treat, both
in terms of outcomes as well as clinician-patient
interactions (10, 63). The reasons for this may be
multifactorial including lack of clinician knowledge about evidence-based treatments, lack of access to or inadequate reimbursement for CBT and
other psychotherapeutic interventions, concomitant personality disorders, and limited time in busy
outpatient encounters with other competing demands. Also, there may be selection bias in published trials. For example, despite the consistent
evidence supporting CBT, many such patients seen
in clinical practice may refuse referral to mental
health providers. Those with somatoform disorders
who are convinced their problems are “physical”
may be less likely to enroll in studies of “psychological” treatments.
In summary, there is strong evidence supporting
the efficacy of CBT across several types of somatoform disorders, and moderate evidence supporting
a psychiatric consultation letter in SD and its lower
threshold variants. Antidepressants also seem
promising, particularly for functional somatic syndromes, but require further study in somatoform
disorders per se. The most prevalent type of somatoform disorder is the family of conditions that
includes SD, its lower threshold variants including
medically unexplained symptoms, USD, and pain
disorder. The overlap along a continuum of these
disorders with one another and with functional somatic syndromes has important implications for revised classification in DSM-V as well as common
treatments (54, 64). Also, psychotherapeutic interventions other than CBT (e.g., interpersonal therapy, problem-solving therapy, brief psychodynamic therapy) as well as treatments outside of
what are traditionally considered “psychological”
(e.g., optimizing analgesics, the use of pain selfmanagement programs) merit further study for somatoform disorders. Finally, most trials have studied single treatments, whereas it is likely that
combining treatments may be necessary in patients
with chronic somatic conditions. Because somatoform disorders are as prevalent as depression and
anxiety in primary care and account for considerable disability and costs, enhancing treatment outcomes for this often-neglected category of mental
disorders should be a priority.
INFLUENTIAL
PUBLICATIONS
vided to PCPs was effective in three of four trials,
but specialized PCP training was effective in only
one of three trials. Although substantial differences
between trials make comparisons difficult, several
points should be mentioned. First, although the
consultation letter trials showed modest improvement in physical functioning, none of the trials
reported on somatic symptom outcomes, which is
notable in that all four trials were performed in SD
or its lower threshold variants. Second, the consultation letter trials were all performed by the same
group and had small sample sizes. Nonetheless, the
fact that PCP training trials have not shown a convincing effect means further work is needed to determine the optimal balance between PCP care, collaborative care, or referral for CBT for improving
outcomes of somatoform disorders in primary care.
In terms of type of somatoform disorder, the
most evidence (23 of the 34 trials) (Table 3) exists
for the family of related disorders including SD, its
abridged or subthreshold variants, and medically
unexplained symptoms. Clinical trial evidence for
the treatment for other somatoform disorders
ranges from modest to limited. The evidence supporting CBT in hypochondriasis is consistent
across four trials. Two trials of CBT and one trial of
fluoxetine were beneficial in BDD. A meta-analysis
of treatments for BDD (60) included, in addition
to the RCTs reported here, three case series and one
crossover trial of antidepressants (three with SSRI,
one with clomipramine) involving 89 patients, and
eight case series of psychological treatments (four
with behavioral therapy, three with CBT, and one
with cognitive therapy) involving 85 patients. Including all studies where the effect size could be
derived from the published date, the mean effect
sizes were 0.92 for antidepressants (five studies),
1.43 for behavioral therapy (four studies), and 1.78
for CBT (five studies). Effect sizes of 0.8 or greater
are considered large therapeutic effects (61). Finally, the three small trials in conversion disorder
were inconclusive, yet they are the only trials that
qualified for inclusion in a recent Cochrane Collaboration review (62). Although we found no trials
focusing on DSM-IV Pain Disorder or Undifferentiated Pain Disorder per se, previous evidencebased reviews of antidepressants, CBT, and other
psychological treatments for functional symptoms
had patient samples where pain was often a cardinal
symptom (11–15, 56). Also, many of the trials in
our review that focused on patients with lowerthreshold SD and/or medically unexplained symptoms likely included many patients with pain
symptoms or undifferentiated SD.
Despite the evidence for some potentially effective treatments, many clinicians find somatoform
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NOTES
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