In the June 2005 issue of the Archives of General Psychiatry,
there are four reports by Ronald Kessler and colleagues that
are based on a major psychiatric epidemiological study
(references for these articles are provided at the very end
of this post). For such "major" studies, an editorial is
typically provided in the Archives and I've reproduced
below the one by Insel and Fenton which summarizes the
main points of the studies, identifies their limitations, and
provides info on ongoing and future studies. Looks like
things might be worse than some imagine.
Of particular interest to some readers may be that the
dataset used by Kessler and his colleagues for the reports
will be available via the web -- an address is given below
after the editorial but I'll repeat here:
http://www.hcp.med.harvard.edu/ncs.
******************************************
Arch Gen Psychiatry. 2005;62:590-592.
Vol. 62 No. 6, June 2005
Psychiatric Epidemiology
It's Not Just About Counting Anymore
Thomas R. Insel, MD; Wayne S. Fenton, MD
Over the past 2 decades, the National Institute of Mental
Health supported ambitious population-based efforts in
psychiatric epidemiology. The landmark 5-site Epidemiological
Catchment Area (ECA) study of the 1980s provided the
first comprehensive picture of the prevalence of DSM-III
mental disorders in the United States.1 A decade later, the
National Comorbidity Survey (NCS) was the first study to
estimate the prevalence of DSM-III-R mental disorders in
a nationally representative US sample.2 These studies
established the methods of modern psychiatric epidemiology
in the United States, including the use of reliable lay-administered
structured diagnostic assessment tools to ascertain standardized
diagnostic criteria,3-4 the comparison of clinical interviews
with lay interviews to evaluate diagnostic validity,5-7 and the
application of sampling strategies to identify nationally representative
samples. Combined with earlier and richly informative international
studies in psychiatric epidemiology,8-10 the ECA, NCS, and
related surveys demonstrated that mental disorders were highly
prevalent in the general population and placed mental illness
squarely on the nation's and the world's public health agenda.11
These studies have also changed how we view psychopathology.
Most mental illnesses, for example, begin far earlier in life than was
previously believed. In addition, findings such as the frequency of
comorbidity among the major diagnostic entities have led to
systematic studies of their boundaries and renewed questions
about categorical vs dimensional approaches to classification.
Nonetheless, many critical issues were not addressed by earlier
studies. While the overall 12-month prevalence of any mental
illness was reported to be in the range of 30%, significant
questions about the disability associated with these syndromes
remain. How severe are the disorders reported to be present
in 30% of the population? What is the economic and public
health impact of these conditions? How long is the delay
between onset and diagnosis? And to what extent have we
made progress in providing appropriate evidence-based
treatments to those who are ill?
The 4 articles from the National Comorbidity Survey Replication
(NCS-R) published in this issue of the ARCHIVES address each
of these questions.12-15 The NCS-R uses the international
World Health Organization-Composite International Diagnostic
Interview (WHO-CIDI),6 a fully structured lay-administered
interview, to generate DSM-IV diagnoses from data collected
in a household survey of 9282 respondents (70.9% response rate).
Relative to prior studies, methodological innovations include an
expanded set of diagnoses; in-depth clinical validation of field
research diagnoses based on clinician-administered Structured
Clinical Interview for DSM-IV (SCID) reinterviews7; dimensional
self-ratings on clinically anchored scales16-18; inclusion of
subthreshold diagnostic syndromes; assessment of disability
and impairment; the use of disease burden metrics linked to
marker physical disorders; and assessments of service use,
treatment barriers, and adequacy of treatment.
A single study cannot address all pertinent questions so there
are several limitations to the NCS-R. The survey did not
collect extensive data on relatively low base-rate, disabling
disorders such as schizophrenia and autism. In addition,
sampling required that all respondents speak English and
belong to a household. As a result, non-English speakers,
institutionalized, and homeless individuals were not included
in this survey. There was a relatively high nonresponse rate
(29.1%), but a careful evaluation of nonresponders revealed
no systematic association between nonresponse and
psychopathology.12 In addition, data on age of onset were
obtained retrospectively; there was no prospective arm to
this study. These limitations aside, the results described in
these 4 articles raise several important issues that should
concern readers of the ARCHIVES.
First, as reported in earlier population-based studies, mental
disorders begin in early life and are common and protracted.
As suggested in the WHO Burden of Disease study,19 mental
illnesses are the chronic diseases of the young. Kessler et al12-13
find lifetime history of a mental disorder in 46.4% of their sample;
a 12-month prevalence of 26.2%, with half of all cases reporting
onset by age 14 and three quarters by age 24. What should we
make of these numbers? If one quarter of the population has a
disorder each year, are most mental disorders so mild as to be
trivial? Or are these disorders serious and more prevalent but
underreported?
In the second report, Kessler et al13 address the issue of severity
by demonstrating that nearly 60% of those diagnosed with a
disorder in the previous 12 months are rated as "serious" (22.3%)
or "moderate" (37.3%) rather than "mild." Those rated as serious
(22.3% of 26.2% = 5.8% of the population in the 12-month sample)
reported a mean of 88.3 days when they were unable to carry
out their normal daily activities because of mental or substance
abuse problems. Ratings of serious were most common among
those with bipolar disorder (83%), drug dependence (56.5%),
obsessive-compulsive disorder (50.6%), oppositional-defiant
disorder (49.6%), and mood disorders (45%). Surprisingly,
impulse control disorders, neglected in most previous epidemiological
studies of adults, were found in 8.9% (12-month prevalence) and
24.8% (lifetime prevalence) of the population with a greater
proportion at the serious level than either anxiety or substance
disorders. Corroborating the high rates of comorbidity described
in earlier studies, 45% of those with a 12-month disorder met
criteria for 2 or more disorders. Severity of illness was strongly
related to meeting criteria for more than 1 disorder.
The third report by Wang et al14 demonstrates, as extensively
described in reports from the President's New Freedom
Commission on Mental Health20 and the Surgeon General's
report,21 that mental health care in America is ailing. Over a
12-month period, 60% of those with a disorder (recall that nearly
60% of these are "rated" serious or moderate) receive no
treatment. Indeed, for those with impulse control and substance
abuse disorders, nearly half of all lifetime cases have never been
treated. Among those with any of the disorders who do report
obtaining care, only 32.7% report service that meets criteria
of minimally adequate. While the survey can only crudely estimate
adherence to evidence-based standards and adequacy of
treatment, the sources of care are informative. Those with a
mental or substance use disorder were more likely to receive
help from a general medical professional (eg, primary care
physician or nurse) or a complementary-alternative source
(eg, internet support group) than a psychiatrist. Even for major
depressive disorders, respondents were nearly as likely to
receive services from a non-health care source, such as a
religious or spiritual advisor, as to be treated by a psychiatrist,
yet the survey found that the overall quality of treatment is
much higher in mental health specialty care (minimally adequate
in 48.0% of specialty mental health vs the 12.8% of general
medical and the 13.1% for non-health care sources).14
Finally, a systemic and unacceptable failure in the provision of
care is also reflected in very substantial delays between illness
onset and first diagnosis and treatment.15 Even for mood
disorders, with considerable effort expended to increase public
awareness of detection and treatment, the delay to first treatment
contact ranged from 6 to 8 years. With anxiety disorders, the
delay was even longer, ranging from 9 to 23 years. A number
of factors predict delayed diagnosis, including early onset, male
gender, less education, and racial-ethnic minority status.
Collectively, these articles provide a stark challenge for
psychiatry as a public health discipline. Most of the disorders
assessed by the NCS-R have evidence-based treatments, but
the data suggest that these treatments are rarely provided in the
community. Most psychiatrists practice in office-based specialty
settings, yet most patients obtain care in the general medical
sector. How do patients who receive psychiatric care differ
from those who do not? How can we improve care outside
of the mental health specialty environment?Given that mental
disorders are often life-long illnesses that begin in childhood
or adolescence, how can we ensure care for these patients
equivalent to the care for children with juvenile-onset diabetes
or cystic fibrosis? Regrettably, data from the NCS-R indicate
that we most often fail to identify illness sufficiently early to
intervene and minimize the damaging effects of psychiatric
illness on young peoples' developmental trajectories. With
respect to the detection and appropriate treatment of mental
illness in the United States, the NCS-R quantifies the distance
yet remaining along the path to ensuring that all Americans
have access to timely and high-quality mental health care.
The findings reported here are the first fruit of what promises
to be a bountiful harvest; the NCS-R is one element in a
coordinated program of new psychiatric epidemiological
studies that will be completed over the next several years.1
These include the NCS-A study of adolescent mental health
in the United States that has assessed nearly 10 000 youths
aged 13 to 17 years; the NCS-2, a 10-year follow-up of the
original NCS, that will allow assessment of the natural history
of illness and treatment in a representative sample of the US
population; and the National Study of African American Life
and the National Study of Latino and Asian Americans that
have sampled nationally representative groups of nearly 6000
and 5000 individuals, respectively. Because these studies use
identical diagnostic instruments and share a common core of
predictor, symptom, disability, and service use probes, it will
be possible to combine samples to document, understand,
and potentially remedy mental health disparities in the United
States. Beyond the United States, NCS-R methodology has
been adopted in epidemiological studies under way in 27 other
countries under the aegis of WHO in the WHO World Mental
Health Survey initiative.22 When completed, over 200 000
individuals will have been surveyed, making this the first and
largest international study of mental disorders ever attempted.
Quantifying the prevalence of mental disorders, the disabilities
associated with them, and the adequacy of service provision
forms the foundation for national and international mental
health policy. But psychiatric epidemiology is no longer just
about counting.23 The NCS-R results will yield much-needed
information about the burden of disease, medical comorbidity,
and global patterns of illness. Because it includes subthreshold
diagnostic information, which we know from studies of hypertension
and diabetes can be highly predictive of future diseases, the
results may be informative for studying the effect of early
intervention. Both the sample and findings may also be informative
for future case-control studies of specific subgroups and
population-based genetic studies, as well as a source of empirical
evidence for prevention.
Diagnosis has confounded psychiatry for the past century, with
the DSM approach enhancing diagnostic reliability but not validity.
By empirically defining clusters of symptoms found in
population-based samples, studies such as the NCS-R may
point the way to more valid diagnostic entities. Certainly they
reveal that those we provide diagnosis for in a clinical setting
represent a small fraction of those with disorders, and they
remind us that psychiatry faces one of the greatest public health
challenges in contemporary medicine.
AUTHOR INFORMATION
Correspondence: Dr Insel,
6001 Executive Blvd, Room 8235,
Bethesda, MD 20892-9669 ([EMAIL PROTECTED]).
Submitted for Publication: November 24, 2004; accepted, February 16, 2005.
Additional Information: These data will be available for public use.
Information about access to these public data files as well as the
NCS technical reports can be obtained from the NCS Web page
at http://www.hcp.med.harvard.edu/ncs.
Acknowledgment: The NCS-R project has been the result of a
large team of dedicated program officers and scientists at the
National Institute of Mental Health. Together, Doreen Koretz, PhD,
Lisa Colpe, PhD, Bruce Cuthbert, PhD, and Ellen Stover, PhD,
have nurtured psychiatric epidemiology through several generations
of studies. Kathleen Merikangas, PhD, has served as the National
Institute of Mental Health coprincipal investigator on the NCS-R project.
Thomas R. Insel, MD; Wayne S. Fenton, MD
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14. Wang PS, Lane M, Olfson M, Pincus HA, Wells KB, Kessler RC.
Twelve-month use of mental health services in the the United States:
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Psychiatry. 2005;62:629-640.
15. Wang PS, Berglund P, Olfson M, Pincus HA, Wells KB, Kessler RC.
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RELATED ARTICLES IN ARCHIVES OF GENERAL PSYCHIATRY
Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV
Disorders in the National Comorbidity Survey Replication
Ronald C. Kessler, Patricia Berglund, Olga Demler, Robert Jin,
and Ellen E. Walters
Arch Gen Psychiatry. 2005;62:593-602.
Failure and Delay in Initial Treatment Contact After First Onset of
Mental Disorders in the National Comorbidity Survey Replication
Philip S. Wang, Patricia Berglund, Mark Olfson, Harold A. Pincus,
Kenneth B. Wells, and Ronald C. Kessler
Arch Gen Psychiatry. 2005;62:603-613.
Prevalence, Severity, and Comorbidity of 12-Month DSM-IV
Disorders in the National Comorbidity Survey Replication
Ronald C. Kessler, Wai Tat Chiu, Olga Demler, and Ellen E. Walters
Arch Gen Psychiatry. 2005;62:617-627.
Twelve-Month Use of Mental Health Services in the United States:
Results From the National Comorbidity Survey Replication
Philip S. Wang, Michael Lane, Mark Olfson, Harold A. Pincus,
Kenneth B. Wells, and Ronald C. Kessler
Arch Gen Psychiatry. 2005;62:629-640.
¨ 2005 American Medical Association. All Rights Reserved.
Mike Palij
New York University
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