Copyright 1999 by
The Cerontological Society of America
The Cerontologist
Vol. 39, No. 3, 291-298
We enrolled 543 elderly participants of a managed care organization in a cross-sectional
study to test whether the association between self-rated physical health and clinically
defined illness differs for persons who are not depressed compared with persons with
minor or serious depression. Depression was measured with the Diagnostic Interview
Schedule (DIS). Clinically defined illness was measured with the Chronic Disease Score
(CDS), a pharmacy-based measure. Additional variables included age, sex, and selfreported pain and physical function. Self-rated physical health was associated with both
minor and serious depression, independent of clinically defined illness; minor depression
was no longer significant when self-reported pain and physical function were added to the
model. A significant negative correlation between self-rated physical health and clinically
defined illness was observed for minor and no depression, but no correlation was seen for
serious depression. These results confirm the association between depression and selfrated physical health and emphasize that, for persons with serious depression, self-rated
health provides a less accurate picture of clinically defined illness at both ends of the
spectrum. Also, a diagnosis of minor depression should not forestall investigation of
inconsistencies between patient report and clinical evidence.
Key Words: Depression, Elderly, Chronic disease, Comorbidity, Self-rated health
The Role of Depression in the Association
Between Self-Rated Physical Health
and Clinically Defined Illness
Cynthia L. Leibson, PhD,1 Judith Garrard, PhD,2 Nicole Nitz, MS,2
Lance Waller, PhD,3 Mary Indritz, MS, RPh,4 Jody Jackson,5
Sharon J. Rolnick, PhD,5 and Lori Luepke2
Numerous studies of the factors contributing to selfrated health have reported that self-rated health is inversely associated with psychological distress and/or depression (including Mulsant, Ganguli, & Seaberg, 1997;
Ormel et al.; 1998; Rodin & McAvay, 1992; Shadbolt,
1997; Streib, Suchman, & Phillips, 1958; Tessler &
Mechanic, 1978; Wells et al., 1989). These studies
typically found the association was independent of
self-reported physical illness (i.e., number of chronic
conditions, bed disability days, physician visits). Based
in part on these findings, clinicians are encouraged to
rule out depression when patients report poor physical health in the absence of clinical evidence of disease (Schneider, Reynolds, Lebowitz, & Friedhoff, 1994).
But this interpretation is slightly problematic. It suggests that the association between self-rated health and
clinically defined illness is less for persons who are
This research was supported by AHCPR grant 1RO1 1 BS 0772, Judith
Garrard, Principal Investigator.
Address correspondence to Cynthia Leibson, PhD, Department of Health
Sciences Research, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905.
E-mail: [email protected]
1
Department of Health Sciences Research, Mayo Clinic, Rochester, MN.
Divisions of 2Health Services Research and 3Biostatistics, School of Public
Health, and "Social and Administrative Pharmacy, College of Pharmacy,
University of Minnesota, Minneapolis, MN. 5Health Partners, Research Foundation, Minneapolis, MN.
Vol. 39, No. 3, 1999
291
depressed relative to those who are not depressed.
This was not the hypothesis under investigation in a
majority of the previously referenced studies. A majority did not use objective measures of clinically defined illness. Of those studies that included such
measures (Blazer & Houpt ,1979; Connelly, Philbrick,
Smith, Kaiser, & Wymer, 1989; Friedsam & Martin,
1963; LaRue, Bank, Jarvik, & Hetland, 1979; Linn &
Linn, 1980; Maddox, 1962; McHorney, Ware, & Raczek,
1993), not all had access to valid research measures
of depression; and with rare exception (McHorney et
al., 1993), most measures included depressive symptoms due to physical illness.
When self-rated health and clinically defined illness
are in disagreement, the potential consequences include the following: missed or incorrect diagnoses, increased costs, a belief on the part of prpviders or payors
that patients' health care seeking behaviors are inappropriate, and a belief on the part of patients that the
system is unresponsive to their needs (Barsky, Wyshak,
& Klerman, 1986; Connelly et al., 1989). Given the
current health care environment, with its emphasis
on cost reduction and improved outcomes, including
patient satisfaction, the importance of identifying and
addressing the source of disparities between self-rated
health and clinically defined illness merits increased
attention.
The present study examines the association between
self-rated physical health and clinically defined illness
and tests the hypothesis that this association differs between persons who are depressed and persons who
are not depressed. The advantages of this study include (a) a standardized research measure of depression that excludes symptoms due to physical illness or
injury (Robins, Helzer, Croughan, & RatclHf, 1981) and
(b) a pharmacy-based measure of clinically defined illness,
weighted for disease type and severity (Von Korff, Wagner,
& Saunders, 1992).
The study population consists of elderly members
of a social health maintenance organization (SHMO).
Information about the contribution of depressive
symptoms to the association between self-rated health
and clinically defined illness is especially important in
this age group because the prevalence of both depressive symptoms and physical illness is higher, and
the independent contribution of self-rated health to
health outcomes appears greater for older compared
to younger persons (Dasbach, Klein, Klein, & Moss,
1994; Eaton & Kessler, 1981; Williams, Kerber, Mulrow,
Medina, & Aguilar, 1995).
Methods
This cross-sectional study is part of a longitudinal
investigation of outcomes associated with antidepressant treatment among elderly members of a large
health maintenance organization (HMO; Carrard et
al., 1998). Institutional review board approval was
obtained from both the HMO and the University of
Minnesota. Study participants were drawn from all
persons enrolled in a capitated Medicare package
that combined comprehensive hospital, outpatient, and
prescription drug services with expanded communitybased long-term care benefits in a managed care setting. Data on the sociodemographic characteristics of
each of the members were obtained from the membership database. Because the program was capitated,
the population of all enrollees was known, whether
the individuals used any services.
Measure of Depression
To facilitate identification of persons with depressive symptoms, a two-stage case-finding procedure was
used. The intent of the first stage was to enrich the
sample with persons likely to meet diagnostic criteria
for depressed. In the first stage, members who were
65 years or older on June 21, 1993, and enrolled for
the preceding 12 months (N = 6,198) were mailed
an invitation to participate in the study. They were
asked to complete the enclosed Geriatric Depression
Scale (GDS) form and sign the subject consent form
and return both by mail. The GDS is a 30-item true/
false, self-rating instrument with high sensitivity and
moderate specificity that can be used as a reliable
and valid screening tool for indication of depression
(Yesavage et al., 1982). The GDS was completed and
returned by 3,872 individuals (62% response rate). Respondents were similar to nonrespondents with the
exception that respondents were younger than non292
respondents (mean age ± standard deviation = 74.8
± 5.8 vs 75.8 ± 6.3 years, p < 0.001).
Individuals with a GDS score >11 were considered
as screening positive for depression. The cutoff of 11
was used based on published reports of GDS sensitivity and specificity (Brink et al., 1982). Individuals were
also categorized as having evidence of antidepressant
treatment, based on review of the HMO pharmacy
records for the 12 months prior to GDS administration. Based on sample size calculations, with oversampling of persons on antidepressants and/or with indication of depression, 745 individuals were targeted
for the second stage of case finding.
In order to validate the GDS self-report and to differentiate individuals with serious depression or dysthymia, the second stage of case finding consisted
of a structured telephone interview by trained interviewers. The diagnostic tool used consisted of the Depression and Mania subtests of the National Institute
of Mental Health's Diagnostic Interview Schedule (DIS;
Robins et al., 1981). The DIS determines the presence of depressive symptoms based on Diagnostic
and Statistical Manual of Mental Disorders, third
edition, revised (DSM Ill-R) criteria (American Psychiatric Association, 1987). The DIS was particularly appropriate for this investigation because it queries for
and excludes symptoms due to physical illness, injury,
or medication, thus minimizing problems of colinearity between depression status and clinically defined
illness in the multivariate analyses. Persons with none
of the nine DSM Ill-R symptoms needed to diagnose
major depression were defined as not depressed.
Persons with 1-3 symptoms were defined as having
minor depression. Persons with >4 symptoms were
defined as having serious depression. Extensive validity and reliability studies have been reported for the
DIS and its subsections, including Depression and
Mania. The validity of its use by lay interviewers, the
sensitivity and specificity for DSM Ill-R criteria, and
the test-retest reliability of the instrument have been
previously established (Robins et al., 1981). Although
originally designed as a face-to-face interview, comparability of the telephone and face-to-face interview
has been demonstrated (Wells, Bumam, Leake, &
Robins, 1988).
Of the 745 individuals considered for the second
stage, 22% (n = 163) had either died (n = 13), could
not be contacted (n = 13), were no longer participating in the benefit package (n = 24), or were unable
(n = 60) or declined (n = 53) to complete the interview. Compared to the nonrespondents, the 582
respondents were younger (mean age ± standard deviation = 74.0 ± 6.0 vs 75.8 ± 6.7 years, p = 0.001),
more likely female (67% vs 52%, p < 0.001), and less
depressed as measured by GDS > 11 (56% vs 73%,
p < 0.001).
Clinically Defined Illness
The measure of clinically defined illness used in this
study was Von Korffs and colleagues (1992) chronic
disease score (CDS). The CDS considers patterns of
medication use across 17 chronic disease categories,
The Gerontologist
with one to five classes of medication specified for
each category. The CDS assigns an individual a
weighted score for each chronic disease, depending
on the number of classes of prescription medications
filled in the previous year. The weights were based
on consensus judgement of a panel of experts. Possible scores range from zero (no indication of chronic
disease) to 35. The CDS has been shown to have
high year-to-year stability and to be predictive of subsequent hospitalization and mortality, after adjusting
for gender, age, and previous utilization (Von Korff et
al., 1992). The measure was particularly appropriate
for the present study because medications used in the
management of symptomatic conditions (e.g., analgesics, antidepressants, sedative-hypnotics) were excluded,
thus minimizing problems of colinearity between depression status and clinically defined illness in the multivariate analyses.
A CDS score for each of the study participants was
calculated. The score was calculated at baseline (i.e.,
March 1, 1994) using records of prescription drug use
from the HMO automated pharmacy database for the
prior 12 months. The drug benefit, which consisted
of a $10 co-pay, was limited to drugs purchased within
the program-operated pharmacies. The pharmacy
records included details of all prescription drugs filled
within the HMO's pharmacies, regardless of whether
the cost was more or less than the co-pay. Medications were made available for multimonth periods for
enrollees who traveled or lived outside the area part
of the year. All respondents to the DIS had been enrolled at the start of the project, March 1, 1993. Thus
essentially all prescription drugs purchased by study
participants during the 12 months prior to baseline
were captured within the pharmacy database.
Self-Rated Physical Health
Each of the 582 individuals who responded to the
DIS telephone interview was mailed a survey on
March 1, 1994, to obtain baseline data on health-related quality of life. The response rate was 94% (N =
549). The survey included the MOS Short-form General Health Survey (SF-36) (Stewart, Hays, & Ware,
1988) and the Salamon-Conte Life Satisfaction in the
Elderly Scale (LSES) (Salamon, 1988). The SF-36 and
LSES are self-administered multi-item survey instruments developed to measure well-being. As our measure of self-rated physical health, we elected to use
the response to the LSES query, "Physically I am: unhealthy, somewhat unhealthy, average, healthy, very
healthy." This single item measure is very similar to
that used in a large majority of previous investigations
of factors contributing to self-rated health. We chose
the single item from the LSES over the SF-36 overall
measure of health perceptions for two reasons. The
first was its appropriateness for the hypothesis under
investigation. The LSES query is specific to physical
health. The SF-36 query refers to health in general,
and is therefore potentially confounded by mental
health as well as social and role functioning. The second advantage of the LSES query was the appropriateness for use with elderly subjects. The frequency
Vol. 39, No. 3, 1999
293
distribution of responses to the SF-36 query, "In general, would you say your health is: excellent, very
good, good, fair, poor" revealed a lack of discrimination and skewed distribution; 90% of subjects categorized themselves as good, fair, or poor; only 2% responded excellent.
Pain and Physical Function
The mailed survey responses to the SF-36 afforded
separate measures of pain and physical functioning,
two factors that also contribute to self perceptions of
physical health (Kennedy et al., 1989; Linn & Linn,
1980; Maddox, 1962; Ware, Davies-Avery, & Donald,
1978; Wells et al., 1989). The pain score was based
on two questions: "How much bodily pain have you
had during the past 4 weeks?" ("very severe" to "none")
and "During trie past 4 weeks how much did pain
interfere with your normal work?" ("extremely" to "not
at all"). The physical function score was based on 10
questions ranging from whether a person had difficulty bathing and dressing to whether he/she had
difficulty participating in vigorous activities such as
strenuous sports. Responses ranged from "severe limitations" to "no limitations." Both pain and physical
function were scored from zero to 100. A high pain
score indicated freedom from pain; a high physical
function score indicated increased functioning.
Statistical Analysis
Univariate associations with self-rated physical health
("unhealthy" equal 1 and "very healthy" equal 5) were
tested using chi-square test for sex, Kendall's tau-(3
correlation for depression (DIS 0 = no depression;
DIS 1-3 = minor depression, DIS > 4 = serious depression), and Pearson product moment correlation for
age, clinically defined illness, pain, and physical function. The correlation between self-rated physical health
and clinically defined illness was also stratified by category of depression.
Multivariable regression analysis was used to assess
the contribution of depression to self-rated physical
health, controlling for the other variables. Self-rated
physical health was entered as a continuous variable.
Depression was entered as two dummy variables,
with DIS = 0 as the reference. Sex was entered as
a dichotomous variable; age was entered as two
dummy variables 75-84 years and 85+ years, with
65-74 years as the reference. Clinically defined illness was entered as a continuous variable. The question of whether the contribution of clinically defined
illness to self-rated physical health differs between
persons who are depressed and those who are not
depressed was assessed by considering interactions between CDS and the two DIS variables. Because the
relationships between depression and self-reported
pain and physical functioning are not clearly isolated,
we began by fitting models without pain and physical
functioning, then considered their possible confounding effects. Statistical significance was accepted when
p<0.05.
Number of
Individuals
0
2
4
6
8
10
12
14
16
Chronic Disease Score
Figure 1. Distribution of persons by Von Korff and colleagues' Chronic Disease Score (Von Korff et al., 1992).
CDS, is provided in Figure 1. The 218 individuals
(40%) with no clinically defined illness (CDS = 0) included 12 persons with no pharmacy entries for the
12-month period.
Table 1 shows characteristics by categories of selfrated physical health. Responses to the LSES question
about self-rated physical health were fairly symmetrically distributed. The proportion of females was similar across all categories (cni square= 0.96, p = 0.92).
The association between age and self-rated physical
health was not significant (p = 0.145). Overall, selfrated physical health worsened as clinically defined
illness increased. Self-rated physical health was also
negatively correlated with depression; 69% of indi-
Results
Five hundred forty-three of the 549 respondents to
the general health survey responded to all the questions under consideration. The mean age was 75 ± 6
years; 72% were female. Forty-seven percent (n =
257) had no depressive symptoms (DIS = 0), 4 1 %
(n = 222) had minor depression (DIS = 1-3), and
12% (n = 64) had serious depression (DIS > 4). In
interpreting these percentages, it is important to remember that study participants were not a random
sample of the elderly population (i.e., individuals who
scored depressed on the GDS were oversampled). The
distribution of clinically defined illness, measured as
Table 1. Characteristics by Category of Self-Related Physical Health
Somewhat
Age, years
Mean (SD)
% Female
Clinically defined illness
Mean CDS (SD)
Depression
% DIS = 0
% DIS = 1-3
% DIS > 4
Freedom from pain
Mean (SD)
Physical functioning
Mean (SD)
n = 115
Very
Healthy
n = 22
Correlation
Coefficient
75 (6)
72
74 (6)
69
76 (6)
73
-0.097 a
—
5.6 (3.4)
4.1 (3.1)
2.8 (2.4)
2.2 (2.0)
-0.40 a *
31
51
18
39
45
16
47
42
11
64
31
5
69
27
4
-0.20 b *
36 (23)
44 (23)
57 (23)
74 (24)
83 (16)
0.51 a *
15 (15)
32 (25)
55 (28)
68 (28)
85 (17)
0.58a*
Unhealthy
Unhealthy
n = 57
n = 167
Average
n = 182
76 (6)
70
75 (6)
74
6.8 (3.6)
Healthy
a
Pearson product moment.
Kendalls's tau (3.
*p < 0.001.
b
294
The Gerontologist
viduals who rated themselves "unhealthy" exhibited
depressive symptoms (51% had 1-3 symptoms and 18%
had >4 symptoms) compared to 31% of those who
rated themselves "very healthy" who exhibited depressive symptoms (27% with 1-3 symptoms and 4% with
>4). Self-rated physical health was positively correlated with both physical functioning and freedom from
pain. Additional analyses revealed physical functioning and freedom from pain were both negatively
associated with depression (Kendall's tau-|3 = -0.142,
p < 0.001, and Kendall's tau-(3 = -0.198, p < 0.001,
respectively).
Figure 2 reveals the association between self-rated
physical health and clinically defined illness for each
category of depression. For persons with no depressive symptoms and those with minor depression,
self-rated physical health improved significantly as
clinically defined illness decreased (Pearson correlation = -0.437, p < 0.001 for DIS = 0; Pearson correlation = -0.392, p < 0.001 for DIS 1-3). For persons with serious depression, however, the inverse
association between self-rated physical health and
clinically defined illness was not apparent (Pearson
correlation = -0.179, p = 0.157).
This finding was investigated further. Persons with
no depression, those with minor depression, and those
with serious depression were compared for clinically
defined illness, stratified by self-rated physical health
categories: "unhealthy or somewhat unhealthy," "average," and "healthy or very healthy." No significant
differences were found with the following exception:
As is apparent in Figure 2, among persons who rated
themselves "healthy or very healthy," persons with
serious depression exhibited higher clinically defined
illness than persons with no depression (analysis of
variance, combined sum of squares = 33.8, p = 0.037).
In this regard, it is important to note the small numbers of persons with serious depression who rated
themselves either healthy (n = 6) or very healthy
(n = 1).
The above univariate findings were consistent with
results from multivariable regression in Table 2. The
first model was limited to an examination of the main
effects of age, gender, clinically defined illness, and
depression on self-rated physical health. The results of
this model revealed that self-rated physical health did
not differ significantly across aee categories, but selfrated physical healtn declinea as clinically defined
illness increased.'When controlling for clinically defined illness, both persons with 1-3 depressive symptoms and those with >4 symptoms rated their physical health poorer than did persons with no depressive
symptoms.
me addition of interactions to the main effects model
(Table 2, Model 2) revealed a significant interaction
between CDS and DIS > 4. This finding suggests that,
for persons with serious depression, the association
between self-rated physical health and clinically defined illness is weaker than that observed for persons
with no depressive symptoms. But the absence of
a significant interaction between CDS and DIS 1-3
(p = 0.20) suggests that the association between selfrated physical health and clinically defined illness did
not differ between persons with no depressive symptoms and those with minor depression.
Separate analyses were performed to assess the effect of self-reported pain and physical function on the
above findings. The results of the full model, which
Clinically
Defined Illness 4(Mean CDS) 3
Serious Depression
Minor Depression
No Depression
Unhealthy Somewhat
Unhealthy
Average
Healthy
Very
H§althy
Self-rated Physical Health
Figure 2. The mean Chronic Disease Score (Von Korff et al., 1992) for individuals within each category of self-rated physical health
by depression status. Self-rated physical health categories were defined by responses to the Life Satisfaction in the Elderly Scaie (Salamon,
1988) query, "Physically I am." Depression status was measured using the Diagnostic Interview Schedule (DIS; Robins et al., 1981).
Persons with DIS = 0 were defined as not depressed, those with DIS = 1-3 were defined as exhibiting minor depression, and those
with DIS > 4 were defined as exhibiting serious depression.
Vol.39, No. 3, 1999
295
comorbid depression (Blazer & Houpt, 1979; Connelly
et al., 1989; Mulsant et al., 1997; Waxman, McCreary,
Weinrit, & Carner, 1985; Wells et al., 1989). This recommendation is supported by our findings for serious
depression. However, based on results for DIS =
1-3, a slightly different interpretation may apply for
minor depression. It might be speculated that, when
a patient reports poor pnysical health in the absence
of clinical evidence, the presence of minor depression may reflect other factors that are poorly captured
by laboratory tests and diagnostic rubrics (e.g., limitations in physical function and pain). This interpretation is supported by the results when these two variables were added to the main effects model.
Certain qualifications must be placed on this interpretation of study findings. Both physical functioning
and freedom from pain were assessed with subjective self-report. Analyses revealed that these variables
were negatively correlated with the measure of depression. Although it is likely that limitations in functioning and pain contribute to depression, it is also
possible that persons who are depressed report more
limitations or more pain. In addition, although these
baseline data were collected as part of a longitudinal
study, the DIS diagnostic measure of depression was
assessed only at baseline. Thus, sequential measures
of depression were not available; the cross-sectional
study design was generally uninformative about underlying mechanisms or sequence of events.
It should also be emphasized that this was not an
epidemiologic study, undertaken with the intent of
providing population-based estimates. This study was
limited to HMO participants enrolled in a capitated
Medicare package. The generalizability to other populations, especially non-elderly populations, is not
known. This was emphasized by our finding that,
after adjusting for clinically defined illness, pain, and
physical functioning, persons age 85 years and older
rated themselves healthier than persons age 65-74
years. If older adults are more reluctant than younger
adults to complain, either about physical problems or
depression, our finding that minor depression was not
significantly associated with self-rated health when
other variables were in the model (Table 2, Model 3)
may not hold for non-elderly populations. The generalizability of study findings is also tempered by the
study design; persons who screened positive for depression and those who were on anticlepressant treatment were intentionally oversampled. There was an
observed response bias toward younger, female, less
depressed respondents.
The advantages of the present study over most previous investigations lie largely with the instruments for
measuring depression and clinically defined illness. Measures of depression in the earliest studies (Friedsam &
Martin, 1963; Streib et al., 1958; Tessler & Mechanic,
1978) were often unique to the individual study, and
the constructs being measured were not always clearly
defined. More recent studies used standardized instruments with documented evidence of reliability and
validity; however, with few exceptions (McHorney et
al., 1993; Ormel et al., 1998; Wells et al., 1989) the
instruments employed by these studies included de-
Table 2. Multivariable Regression Analyses of Factors
Associated With Self-Rated Physical Health
Model
1
Independent Variables
Age
75-84 years
85+ years
-0.055
(-0.177)
-0.059
(-0.126)
0.000
(0.003)
0.001
(0.004)
Clinically defined illnesss - 0 . 3 8 0 * * *
(low to high CDS)
(-0.115)
Depression
% DIS = 1-3
% DIS > 4
2
3
0.014
(0.030)
0.093**
(0.338)
-0.466***
(-0.141)
-0.189***
(-0.057)
-0.136**
(-0.282)
-0.199**
(-0.415)
-0.055
(-0.114)
-0.170***
(-0.542)
0.304***
(-0.966)
-0.084*
(-0.267)
CDS x DIS 1-3
—
0.103
(0.030)
—
CDS x DIS > 4
—
0.176*
(0.100)
—
Freedom from pain
(poor to good)
—
—
0.217***
(0.008)
Physical functioning
(poor to good)
—
—
0.388***
(0.010)
Adjusted R2
0.19
0.20
0.42
Note: Standardized coefficients are presented with unstandardized coefficients in parentheses.
*p < 0.05; **p < 0.01; * * * p < 0.001.
considered all main effects, are shown in Table 2, Model
3. After adjusting for pain and physical function, persons age 85 years and older rated themselves healtnier
than persons age 65-74 years. The negative association between self-rated physical health and serious
depression (DIS >4) remained significant. But the independent association between minor depression (DIS
1-3) and self-rated physical health was no longer apparent (p = 0.12) when freedom from pain and freedom from physical function were added to the model.
Discussion
This study of elderly members of an HMO found
self-rated physical health was significantly and independently associated with minor depression, serious
depression, and clinically defined illness. The strength
of the negative association between self-rated physical health and clinically defined illness was similar for
persons with no depression and those with minor depression. The association was weaker for persons with
serious depression. When self-reported pain and physical function were added to the main effects model,
the significant association between self-rated physical
health and minor depression was no longer apparent.
The well-demonstrated association between depression and self-rated health has led to heightened
clinical awareness about the need to detect and treat
296
The Gerontologist
pression due to physical symptoms, thus the independent contribution of each to self-rated health is difficult to determine. The DIS measure of depressive symptoms employed in the present study has an advantage
in this respect; subjects are queried following each
positive response as to whether the symptom was due
to physical illness, injury, drugs, medication, or alcohol. Symptoms due to these conditions are not
counted toward the depressive symptoms score.
Measures of physical illness in a majority of previous studies consist of self-reported number of disability days, number of medications, or number of specified medical conditions (Mulsant et al., 1997; Ormel
et al., 1998; Shadbolt, 1997; Wells et al., 1989). The
limitations of self-report with respect to knowledge and
recall bias are well demonstrated (Roberts, Bergstralh,
Schmidt, & Jacobsen, 1996). But most importantly for
studies such as this, self-reports of physical illness are
dependent upon subjective perceptions (Tessler &
Mechanic, 1978). The present study employed a standardized global measure of clinically defined illness
that was based on data obtained from a pharmacy
database. The measure was therefore more objective
than measures based on self-report. It should be noted,
however, that although the instrument was standardized, assignment was not (i.e., whether an individual
was prescribed medication was determined in part by
whicn clinician was seen and whether, when, and how
often the subject presented for care). A more reliable,
objective assessment of clinically defined illness would
have been afforded with standardized physical examinations of all study subjects performed contemporaneous with the assessment of depression and self-rated
health. Physical examinations were in fact used to obtain measures of clinical illness in some of the earlier
investigations (Friedsam and Martin, 1963; Maddox,
1962; Streib et al., 1958). However, with rare exception (Linn & Linn, 1980), these examinations were
not standardized and the reliability of the estimates
was not assessed. Additionally, clinically defined illness based on physical examinations was typically limited
to a dichotomous distinction between ill ana not ill.
The measure used in the present study allowed for a
range of illness ratings. It was not limited to counts of
diagnoses, medications, or disability days, but was weighted
to incorporate disease severity and chronicity.
The question of whether the association between
self-rated health and physical illness differs between
persons who are and are not depressed has been addressed with at least one other recent study. In an
investigation of factors contributing to self-rated health
in older adults, Mulsant and colleagues (1997) tested
for and found no interaction between their measures
of physical illness and minor depression. In contrast
to findings presented here, Mulsant and colleagues also
found no interaction between physical illness and serious depression. Also, minor depression remained significantly associated with self-rated health, after adjusting for limitations in functioning. The Mulsant and
colleagues study differs from ours in that they includea sociodemographic variables not available in
our study, physical illness was assessed by self-report,
their measure of depression included symptoms due
Vol.39, No. 3, 1999
297
to physical illness, and our model included a measure
of pain.
In conclusion, the significant association between
depression and self-rated physical health, independent
of clinically defined illness, reported here is consistent
with numerous other reports. It is generally supportive of the recommendation that patients with somatic
complaints for which there is no objective clinical evidence should be screened for depression. However,
the findings also emphasize the complexity of the relationship between physical and mental illness (Calahan,
Kesterson, & Tierney, 1997) and serve as a caveat.
Persons with serious depression may rate their health
worse or better than clinical evidence suggests. In addition, when a patient's report is inconsistent with clinical
evidence, evidence of minor depression should not
preclude further investigation of physical explanations.
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Received September 15, 1998
Accepted March 12, 1999
INTERGENERATIONAL AND AGING,
AGRICULTURAL AND EXTENSION EDUCATION
PENN STATE seeks applicants for a tenure-track assistant/
associate professor starting October 1999, or as negotiated.
Position has 75% extension and 25% research responsibilities
in the area of adult development and aging that include providing statewide leadership for extension programs; strengthening intergenerational relationships and competencies in
children, youth, and families across the life span; improving
family care of aging and disabled persons; promoting opportunities of intergenerational relationships in civic and family
settings; developing a funded research program to support extension programming; and contributing to the department's
strategic plan. Qualifications include a doctorate in gerontology, human development and aging, family and consumer sciences, developmental education, family sociology or closely
related interdisciplinary fields. Candidates should have a
strong background in intergenerational and extension education as well as applied research. Salary is competitive and
commensurate with background and experience. An attractive
benefits package is available. Applicants should submit a letter of application, resume, academic transcripts, and names
and addresses of three professional references to: Marilyn M.
Furry, Search Committee Chair, 323C Agricultural Administration Building, The Pennsylvania State University, University Park, PA 16802. Closing date is August 1, 1999, or until
a qualified candidate is identified. AA/EOE.
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