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19
Studying Outcomes for Patients with
Depression: Initial Findings From the
Medical Outcomes Study
M. Audrey Burnam
My purpose is to describe work that my RAND colleagues and I have
conducted to examine outcomes for patients with depression. I will summa-
rize our approach and then some initial findings from the study.
THE MEDICAL OUTCOMES STUDY
Our work was done as part of the National Study of Medical Care Out-
comes (the Medical Outcomes Study, or MOS). The MOS was designed to
examine the impact of different health care systems on the processes and
outcomes of care for patients with specific chronic conditions. Four conditions
were selected to be the focus of the study: depression, coronary heart
disease, diabetes, and hypertension.
HEALTH CARE SETTING
Because we wanted to understand the outcomes of care as practiced in
usual circumstances and did not want to disrupt naturally occurring rela-
tionships between patients and providers, this was an observational study.
Clinicians and patients were selected on the basis of the health care systems
that they had chosen. As a result, there were likely to be differences in
patient characteristics-for example, severity of the target condition, stage
of treatment, and complicating comorbidities that could affect outcomes,
independently of the quality of care received. To estimate the effect of the
health care system on outcomes in this study, it was necessary to assess
patient characteristics that might affect these outcomes. The plan, then,
was to control for patient differences across health care settings by statisti
160
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DEVELOPMENT AND USE OF OUTCOMES MEASURES
161
catty adjusting for these differences, a strategy sometimes referred to as
. .
case-m~x adjustment.
The study was designed to compare care received in three types of health
care systems: (a) single-specialty small group and solo practices represent-
ing the traditional, largely fee-for-service, private practice sector; (b) health
maintenance organizations (HMOs), large health care organizations repre-
senting the major prepaid alternative to traditional private practice care; and
(c) large multispecialty group practices, a rapidly growing alternative that
includes significant prepaid as well as fee-for-service financing. The study
was conducted in three cities Boston, Chicago, and Los Angeles with
each system of care studied at each site.
INITIAL SAMPLES
More than 500 providers were recruited. They were selected to represent
specialty groups providing the majority of care to patients with the four
target conditions. The medical providers included in the study were inter-
nists, family practitioners, cardiologists, endocrinologists, and diabetologists.
Mental health specialty providers included psychiatrists and psychologists.
The outpatient practices of these clinicians provided the patient sample.
Patients visiting these practices over a short period (nine days on average)
were screened in the initial, baseline phase of the study to determine whether
they had one of the target conditions. Persons identified by the study as
having one of the targeted chronic conditions were recruited into a two-year
longitudinal panel to follow their outcomes. Over 22,000 patients were
screened initially.
THE STUDY OF DEPRESSION
Depression was selected to be studied in the MOS because of its impor-
tance from a health policy perspective. Some background information will
illustrate this.
First, it is clear from recent epidemiological studies that depression is a
very common mental disorder. One in 20 persons has experienced it at
some time, and one in 40 persons is currently experiencing it (1,2~. I am
not referring here to transient spells of depressed mood or demoralization,
but to distinct, clinically defined syndromes that are characterized by mul-
tiple and persistent symptoms and that tend to occur as repeated episodes of
illness lasting from a few months to years. Second, depression has serious
consequences for the affected individual and his family and for society.
About 15 percent of depressed individuals commit suicide within 10 years
after onset of the illness (3,4~. Depression can often be socially and occu-
pationally debilitating (5,6~. Depressed persons use considerable health
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EFFECTIVENESS AND OUTCOMES IN HEALTH CARE
care resources (7) and may present with somatic symptoms or nonspecific
complaints when seeing a provider in primary care settings (8~. Unless the
depression is recognized and treated, inappropriate use of services is likely
to result (9~.
Third, most depression can be successfully treated. Sufficient evidence
has accumulated to support the efficacy of a variety of pharmacological and
psychosocial therapies (10~.
Finally, about two-thirds of persons with depression are not receiving
treatment (11~. Although most people with depression do visit medical care
providers (12), the literature suggests that medical providers often fail to
detect depression in their patients (13~.
Taking all these points together, we can hypothesize that important dif-
ferences exist across health care settings in the detection of depression and
the subsequent quality of care provided to depressed patients. We may
further hypothesize that such differences have important implications for
patients and for society.
The MOS focused on two specific types of depressive disorders, major
depression and dysthymia. The definitions of these were based on the
diagnostic criteria of the American Psychiatric Association. Major depres-
sion is characterized by persistent depressive mood or loss of interest in
nearly all usual activities. It is accompanied by such symptoms as distur-
bances in appetite, weight, and sleep; psychomotor agitation or retardation;
decreased energy; feelings of worthlessness or guilt; difficulty concentrating
or thinking; and thoughts of death or suicide or attempts at suicide. A
cluster of such symptoms must be present nearly every day for a period of
at least two weeks.
Dysthymia is also characterized by depressed mood or loss of interest in
nearly all usual activities. However, dysthymia lasts longer than major
depression (it must last at least two years to meet diagnostic criteria) and
the symptoms are less severe. The two disorders commonly coexist. That
is, a major depressive episode may be superimposed upon underlying dysthymia.
IDENTIFYING PATIENTS WITH DEPRESSION
Because primary care providers, in particular, may underdetect depres-
sion in their patients, it was important to base our case identification method
on direct assessment from the patient. To screen over 22,000 patients for
the presence of depression, we used a two-stage case identification strategy.
At the first stage, we administered a very brief (eight-item) screen for de-
pression that patients completed themselves while waiting in their providers'
offices (141. To patients who exceeded a specified score, we subsequently
administered a structured diagnostic interview by telephone. The interview
was designed to help us determine a specific diagnosis and to collect infor
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DEVELOPMENT AND USE OF OUTCOMES MEASURES
163
mation on history and severity of depression for use in case-mix adjust-
ment. About one-third of those who screened positive for depression at the
first stage were determined to have met criteria for current major depression
or dysthymia.
ASSESSING OUTCOMES
Once we had identified depressed patients, a sample was recruited to the
longitudinal study. Both generic and depression-specific outcomes were
assessed periodically in the longitudinal study. Generic outcomes were
assessed initially, to provide a baseline, and once every six months thereaf-
ter. The generic outcomes consisted of brief, self~administered measures of
functional status and well-being that have been developed and extensively
tested at RAND (15~. The functioning scales encompass physical, social,
and role functioning. Items on the physical functioning scale ask about
limitations due to health in activities such as sports, climbing stairs, walking,
dressing, and bathing. Role functioning refers to the extent to which health
interferes with work, housework, or schoolwork. Social functioning is the
extent to which health interferes with social activities such as visiting friends
or relatives. Well-being measures include general perceptions of current
health (such as feeling well or ill) and the degree of body pain experienced.
There is evidence that each of these measures reliably represents a single
outcome dimension (161.
Depression-specific outcomes were assessed once every year by means
of a structured telephone interview. This interview elicited information on
number and duration of spells of depression during the past year, including
whether each spell met criteria for major depression or dysthymia. In addi-
tion, the interview determined whether a complete recovery from depression
had occurred during the past year, and if so, for how long. This information
was used to construct a number of outcome indicators. Some indicators
reflect the current level of depression at the time of follow-up: these include
type of depression diagnosis (if any) and number of current symptoms.
Other indicators represent the course of the disorder during the past year:
whether a recovery occurred, and in the case of recovery, whether there was
a relapse (onset of a subsequent depressive episode). Finally, we examined
the number and persistence of depressive symptoms during the past year.
As I mentioned earlier, to compare patient outcomes across different
health care settings using an observational design, one must identify baseline
patient characteristics that may affect the course of depression. In the
baseline phase of the MOS, we comprehensively assessed factors that are
believed to be of some prognostic significance in depression. These in-
cluded demographic and socioeconomic characteristics, medical comorbidity,
the presence of other psychiatric disorders (particularly anxiety disorders,
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EFFECTIVENESS AND OUTCOMES IN HEALTH CARE
psychotic symptoms, and substance use disorders), the type and severity of
depression at baseline, and lifetime history of depressive symptoms and
episodes. We also, of course, controlled for generic measures of function-
ing and well-being at baseline.
RESULTS OF THE DEPRESSION STUDY
FINDINGS FROM THE BASELINE DATA
I would like to summarize some results from our analyses of the baseline
data. We have arrived at estimates of the prevalence of depression among
patients in these health care systems (17~. In practices of mental health
specialists, about 25 percent of visiting patients on any given day currently
had depression. The treatment of this disorder thus occupies much of men-
tal health specialty practice. The prevalence of depressed patients in prac-
tices of general medical physicians was lower, as we would expect, but
even so it was strikingly high present in S percent of patients. This high
rate of depression in medical practices was similar for each of the three
health care systems and was similar across sites. It was similar in practices
of family practitioners, internists, and medical subspecialists. The rate of
depression in medical outpatients is double the rate found in the general
population.
We also learned that medical providers detected depression in only one-
half of their currently depressed patients (18~. The rate of detection was
significantly lower for patients in prepaid care than for patients in fee-for-
service care. These results the high prevalence and low rates of detection
of depression in medical practices suggest that one important determinant
of depression outcomes across health care settings may be the extent to
which it is detected and any treatment provided.
Another set of baseline findings illustrated the importance of case-mix
adjustment. Among patients with current depression, those visiting mental
health providers had a more severe pattern of depressive symptoms than did
those visiting medical providers (19~. Depressed patients of medical pro-
viders, on the other hand, were more likely to have chronic medical condi-
tions. The differences were not great patients of both mental health and
medical providers had, on average, severe depression, a pernicious history
of past depression, and much medical comorbidity. For example, patients
of mental health providers typically had 14 depression symptoms, compared
to 12 symptoms among patients of medical providers. We know, however,
that differences of this magnitude will have a substantial impact on the
course of depression (20~.
We also examined the levels of functioning and well-being experienced
by patients with depression, compared to those experienced by patients with
various chronic medical conditions (21~. In this analysis, we estimated the
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DEVELOPMENT AND USE OF OUTCOMES MEASURES
165
levels of functioning and well-being that were uniquely associated with
depression and with each specific chronic condition (holding other factors,
such as demographic characteristics and comorbidity, equal).
Figure 1 illustrates the results. The zero level on the vertical axis repre-
sents the average level of functioning and well-being of patients with no
chronic medical or mental health conditions. Positive numbers along the
vertical axis represent the extent to which patients with depression and
chronic medical conditions have poorer functioning arid well-being than
those with no chronic conditions. For example, the physical functioning of
patients with depression is 10.5 points poorer than that of patients with no
chronic condition. The figure also shows results for some of the other
chronic medical conditions that we examined angina, advanced coronary
artery disease, arthritis, diabetes, and hypertension.
The physical functioning of patients with depression is worse than that of
patients with most other conditions (including diabetes, arthritis, and hyper-
tension) but better than that of patients with advanced coronary artery disease
or angina. Social functioning of patients with depression is worse than that
of patients with any of the other chronic conditions we studied. Role func-
tioning of patients with depression is about the same as for patients with
angina. Depressed patients perceived their general health as poorer than did
patients with most other conditions and about the same as patients with
30
20
10
o
-1
16.9
10.5 ~
- Ff
t2 ~
_.
10.7
me,
.-.
....
.--.
. _
5.0
30.2
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·:-:
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:-:
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18.2 .-.,
16 9 ~ .:~
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9.9
[~ Depression
~3
Angina
Advanced coronary artery disease
Arthritis
Diabetes
Hypertension
17 0 14.9
/15.1 15.8
-0.3
Physical Social Role Perceived Pain
Functioning Functioning Functioning Health
FIGURE 1 Levels of Functioning on Five Measures of Health Status Among Pa-
tients Enrolled in the Medical Outcomes Study.
NOTE: Higher scores imply poorer functioning.
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166
EFFECTIVENESS AND OUTCOMES IN HEALTH CARE
heart conditions. Finally, patients with depression experience more pain
than patients with most other medical conditions, except for arthritis. The
overall pattern of results across these measures indicates that the function-
ing and well-being of depressed patients is similar to or worse than that of
patients with other major, chronic medical conditions.
Besides measures of functioning and well-being, which can be affected
by cognitive biases known to be associated with depression (such as pessi-
mism), we also looked at a more "objective" measure of functioning days
spent in bed in the past month. What we found is that depression is associ-
ated with more days in bed than any other chronic medical condition except
current advanced coronary artery disease.
PRELIMINARY FINDINGS FROM THE LONGITUDINAL DATA
At this point, we are in a preliminary stage of analyzing the longitudinal
data. We have begun to examine baseline predictors of depression-specific
outcomes one year later, including the probability of recovery, and the
severity and persistence of symptoms throughout the year (201. We have
discovered that these measures of the clinical course of depression are quite
sensitive to the severity of depression at baseline and also the severity of
prior history of depression. Finally, we know that the presence of certain
chronic medical conditions at baseline also affects the subsequent course of
depression (22~.
We have not yet compared depression-specific outcomes across health
care settings, but we have learned two things that are important for under-
taking these comparisons, which are the next step in our work. First, we
have identified some depression-specific indicators that should be relatively
sensitive outcomes for our comparisons across health care settings. Second,
we have identified a number of baseline patient characteristics, particularly
severity of depression, which need to be included as case-mix adjustment
factors in comparisons of health care settings.
CONCLUSION
I will end with a couple of thoughts. First, it is dangerous for us to
forget about mental health when we start to think about health effectiveness
and outcomes. I was happy to see that, although depression is not on the
short list of conditions for the HCFA initiative, it is on the long list.
Depressive disorder is highly prevalent in medical care settings, and there is
~Editors' Note: The reference is to the list of clinical conditions recommended
by an Institute of Medicine committee for high priority attention in the Effectiveness
Initiative. See Institute of Medicine. Effectiveness Initiative: Setting Priorities for
Clinical Conditions. Washington, D.C.: National Academy Press, 1989.
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DEVELOPMENT AND USE OF OUTCOMES MEASURES
167
much that we can learn from an examination of the effectiveness of care for
depression. If we ignore depression, its impact on general outcomes such
as functioning and well-being are nonetheless going to emerge in our stud-
ies of other health conditions.
A second issue is whether, from a measurement perspective, we are
ready to begin studying outcomes as a part of health care effectiveness
studies. With respect to generic measures of functioning and well-being, I
agree with John Ware that we are ready to begin using generic measures in
large-scale efforts.2 There exist brief, patient-administered generic mea-
sures that have established reliability, that are responsive to changes in
patient state, and that are responsive to differences across conditions. I
think these measures are ready to be used. I also think that the field is
ready, at least for certain conditions, to assess disease-specific outcomes.
We may not, however, be quite able to determine the factors responsible
for differences in outcomes across care settings when using observational
study designs. Although we want to be able to attribute outcomes to quality
of care, outcomes can be a function of patient case-mix differences. To
make inferences to quality of care we will have to make sure that we have
controlled well for case-mix. So far, brief case-mix measures are not avail-
able, and there are difficulties in developing measures of case-mix differences.
We have to isolate, from all of the possible confounding patient selection
factors, those that are relevant for the specific outcomes of interest.
One way to approach this problem is to continue to do observational
studies in which we have comprehensively assessed case-mix, so that we
can begin to learn which case-mix factors are important. I think we can
also begin to distinguish effects of case selection and effects of quality of
care by looking very closely at the process of care in any study of patient
health outcomes. We can have greater confidence in attributing differences
in outcomes to differences in health care delivery systems once we under-
stand how the process of care varies across systems.
REFERENCES
1. Robins, L.N., Helzer, J.E., Weissman, M.M., et al. Lifetime Prevalence of
Specific Psychiatric Disorders in Three Sites. Archives of General Psychiatry 41:949-
958, 1984.
2. Regier, D.A., Boyd, J.H., Burke, J.D., et al. One-Month Prevalence of Mental
Disorders in the United States. Archives of General Psychiatry 45:977-986, 1988.
3. Guze, S.B. and Robins, E. Suicide and Primary Affective Disorders. British Journal
of Psychiatry 117:437-438, 1970.
4. Coryell, W., Noyes, R., and Clancy, J. Excess Mortality in Panic Disorder
2For more discussion of this point and for further elaboration of the MOS, see
Chapters 15-17 (23, 24, 25) in this volume.
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EFFECTIVENESS AND OUTCOMES IN HEALTH CARE
A Comparison with Primary Unipolar Depression. Archives of General Psychiatry
39:701-703, 1982.
5. Stoudemire, A., Frank, R., Hedemark, N., et al. The Economic Burden of
Depression. General Hospital Psychiatry 8:387-394, 1986.
6. Weissman, M.W. and Paykel, E.S. The Depressed Woman: A Study of Social
Relationships. Chicago: University of Chicago Press, 1974.
7. Houpt, J.L., Orleans, C.S., George, L.K., et al. The Role of Psychiatric and
Behavioral Factors in the Practice of Medicine. American Journal of Psychiatry
173:37-47, 1980.
8. Klerman, G.L. Other Specific Affective Disorders. Pp. 1305-1309 in Kaplan,
H.I., Freedman, A.M., and Sadock, B.J., eds. Comprehensive Textbook of Psychia-
try III, vol. 2. Baltimore: Williams & Wilkins, 1980.
9. Katon, W. Depression: Somatic Symptoms and Medical Disorders in Primary
Care. Comprehensive Psychiatry 23 :274-287, 1982.
10. Paykel,E.S.,ed. Handbook of Affective Disorders. New York: Guilford Press,
1982.
11. Shapiro, S., Skinner, E.A., Kessler, L.G., et al. Utilization of Health and
Mental Health Services. Archives of General Psychiatry 41:971-982, 1984.
12. Regier, D.A., Goldberg, I.D., and Taube, C.A. The De Facto US Mental
Health Services System. Archives of General Psychiatry 35:685-693, 1978.
13. Kessler, L.G., Amick, B.C., and Tompson, J. Factors Influencing the Diag-
nosis of Mental Disorders Among Primary Care Patients. Medical Care 23:50-62, 1985.
14. Burnam, M.A., Wells, K.B., Leake, B., et al. Development of a Brief
Screening Instrument for Detecting Depressive Disorders. Medical Care 26:775-789,
1988.
15. Stewart, A.L., Greenfield, S., Hays, R.D., et al. Functional Status and Well-
Being of Patients with Chronic Conditions. Journal of the American Medical Asso-
ciation 262:907-913, 1989.
16. Stewart, A.L., Hays, R.D., and Ware, J.E. The MOS Short-Form General
Health Survey: Reliability and Validity in a Patient Population. Medical Care 26:724-
735, 1988.
17. Burnam, M.A., Wells, K.A., Rogers, W., et al. The Prevalence of Depres-
sion in General Medical and Mental Health Outpatient Practices in Three Health
Care Systems. Santa Monica, CA: RAND Corporation, in preparation.
18. Wells, K.B., Hays, R.D., Burnam, M.A., et al. Detection of Depressive
Disorder for Patients Receiving Prepaid or Fee-for-Service Care: Results from the
Medical Outcomes Study. Journal of the American Medical Association, 26:3298-3302,
1989.
19. Burnam, M.A., Wells, K.B., Rogers, W., et al. Severity of Depression in Prepaid
and Fee-for-Service Practices of Mental Health Specialists and General Medical
Providers. Santa Monica, CA: RAND Corporation, in preparation.
20. Wells, K.B., Burnam, M.A., and Rogers, W. One-Year Course of Depres-
sion for Adult Outpatients: Implications for Psychiatric Nosology. Santa Monica, CA:
RAND Corporation, in preparation.
21. Wells, K.B., Stewart, A., Hays, R.D., et al. The Functioning and Well-Being
of Depressed Patients. Journal of the American Medical Association 262:914-919, 1989.
22. Wells, K.B., Rogers, W., Burnam, M.A., et al. Are There Differences in the
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Medical Comorbidity of Depressed Patients by Type of Payment for Services and
Type of Treating Clinician? Santa Monica, CA: The RAND Corporation, in prepa-
ration.
23. Ware, J.E., Jr. Measuring Patient Function and Well-being: Some Lessons
from the Medical Outcomes Study. Pp. 107-1 19 in Electiveness and Outcomes in
Health Care. Heithoff, K.A. and Lohr, K.N., eds. Washington, D.C.: National Academy
Press, 1990.
24. Patrick, D.L. Methodologic Issues in Assessing Health-Related Quality of
Life Outcomes. Pp. 136-151 in Effectiveness and Outcomes in Health Care. Heithoff,
K.A. and Lohr, K.N., eds. Washington, D.C.: National Academy Press, 1990.
25. Cleary, P.D. Using Patient Reports of Outcomes to Assess Effectiveness of
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Application to Clinical Practice:
Introduction
]. Sanford Schwartz, Session Moderator
The ultimate objective of effectiveness research is to improve the health
of our patients and the public. To accomplish this goal, we need to do
several things: (1) we must define what we mean by effectiveness; (2) we
must be able to measure effectiveness in a valid and reliable way (that is, in
a way that is clinically meaningful); (3) we must be able to interpret the
results in a way that will be useful to those delivering and receiving health
care services; and (4) we must present the information to providers and
patients in such a way that its adoption and application are facilitated.
The next four writers discuss how the results of effectiveness research
can be best implemented to change provider and patient behavior, thereby
improving the health of the public. They address such questions as: How
does one change behavior among physicians and patients? What information
is needed to address the concerns of providers and patients? Once this
information is obtained, how can it be presented to patients and providers in
in a way that will get them to change their practices?
Harold C. Sox is chairman of the Department of Medicine at Dartmouth
Medical School. He examines the question of what to do, given valid and
important effectiveness data, to modify the practice patterns of practicing
. .
physlclans.
Albert G. Mulley is an associate professor of medicine and health care
policy and chief of the Section of General Internal Medicine at Massachusetts
General Hospital and Harvard University School of Medicine in Boston.
Dr. Mulley addresses medical decision making from the perspective of patient
preferences and outcomes. His chapter focuses on how to combine this
information in a way that actually changes physician and patient practices.
Stephen C. Schoenbaum is deputy medical director of the Harvard Com-
munity Health Plan (HCHP). He discusses a clinical program evaluation
171
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EFFECTIVENESS AND OUTCOMES IN HEALTH CARE
and management system at HCHP that attempts to measure and manage
variations in clinical practice.
Eugene C. Nelson is director of quality-of-care research at the Hospital
Corporation of America. In his discussion of outcome measures to improve
care delivered by physicians in hospitals, he focuses on what works to
improve the practice of medicine and addresses the question of outcomes
measurement from a system perspective.
Representative terms from entire chapter:
depressed patients
