Copyright 1992 by the American Psychological Association, Inc. 0882-7974/92/S3.00
Psychology and Aging 1992. Vol.7. No. 3, 343-351
Physical Illness and Symptoms of Depression Among Elderly Outpatients Gail M. Williamson
Richard Schulz University of Pittsburgh
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
University of Georgia
Elderly outpatients were assessed to clarify relations between symptoms of depression and physical illness, disability, pain, and selected psychosocial variables. Three types of assessments were made: (a) medical evaluations by physicians, (b) self-reported symptoms of depression and physical health, and (c) demographic and psychosocial data relating to participants' life circumstances. Both objective (physician-rated illness symptoms) and subjective (self-reported health, activity restriction, and use of pain medications) indicators of health accounted for independent variance in symptoms of depression. After controlling for these factors, additional variance was explained by health-related concerns (e.g., health care expenses, service needs), social support, and "other worries" (e.g., feeling useless, becoming a burden to others).
mano & Turner, 1985; Roy, Thomas, & Matas, 1984). Recently, Parmelee, Katz, and Lawton (1991) found significant associations between pain and depression in a sample of institutionalized elderly. Moreover, although depression was correlated with physical illness severity and functional disability, these correlations did not account for the association between depression and pain. In sum, there is abundant evidence indicating that physical health variables (e.g., illness, disability, and pain) are related to increased psychological distress among the elderly. However, the exact nature of the association remains unclear. In particular, both medically diagnosed and self-reported illness have been shown to be related to psychological distress. Although the results of studies using subjective (self-report) measures of health (e.g., Bolla-Wilson & Bleecker, 1989; Palinkas et al., 1990; Phifer & Murrell, 1986; Revicki & Mitchell, 1990) are consistent with those using objective (e.g., physician-rated) measures, there are reasons to suspect that subjective health may be a better predictor of psychological well-being than is objective health. Recently, Pearlman and Uhlmann (1991) found that quality of life among elderly outpatients was more strongly related to subjective perceptions of health than to the more objective (but still self-report) measure of health care utilization. Such findings are problematic because subjective measures of health may be confounded by psychological distress (e.g., Cohen & Williamson, 1988,1991; Schulz, Visintainer, & Williamson, 1990). In particular, individuals who are more psychologically distressed may be more prone to report being in poorer physical health or to exaggerate reports of health care utilization. If this is the case, then the association between actual health status and depressed affect may be weaker than previously believed. Another possibility is that objective and subjective health contribute to psychological distress independently. In other words, it may be that the documented presence of illness per se leads to declines in affect and that negative perceptions of one's own health status further exacerbate this effect. As yet, few studies have compared objective, physician-assessed health status with subjective, self-reported health as pre-
Although the prevalence of major depression is relatively low among the elderly, a substantial proportion report high levels of depressive symptomatology (Blazer, 1989; Palinkas, Wingard, & Barrett-Connor, 1990). For example, two population studies (Blazer & Williams, 1980; National Institute on Aging, 1986) found that 15% of older adults met criteria for being at risk for clinical depression. A factor repeatedly shown to be associated with affect disturbance in the elderly is the presence of physical illness (e.g., Cassileth et al., 1984; LaRue, Dessonville, & Jarvick, 1985; Pfeiffer & Busse, 1973; Stenback, 1980). In a crossnational study of elderly residents of London and New \brk, Gurland et al. (1983) reported that degree of physical illness was the most consistent correlate of pervasive depression (i.e., needing clinical attention). On the basis of these results, Gurland et al. concluded that "physical illness, disability and dependence [are] probably the major determinants of depression in the elderly" (p. 245). Other research supports this conclusion (e.g., Blazer & Williams, 1980; Cheah & Beard, 1980; Conlin & Fennell, 1983; Roth & Kay, 1956). When biological factors have been ruled out as causes of affect disturbance, speculation about mediating mechanisms has often focused on disability. For example, greater functional incapacity in rheumatoid arthritics (Moos, 1964) and inability to perform normal activities in cancer patients (Cassileth et al., 1984) have been shown to be related to poorer mental health. M. Linn, Hunter, and Harris (1980) reported that, after controlling for level of physical disability, physical illness no longer predicted degree of depression. Gurland et al. (1983) suggested that physical disability may be the primary factor accounting for depression among the physically ill. Another potential causal agent is pain. Chronic pain patients of all adult ages show increased rates of depression (e.g., Ro-
This research was supported by Grant RO1 MH41887 from the National Institute of Mental Health (Richard Schulz, principal investigator). Correspondence concerning this article should be addressed to Gail M. Williamson, Department of Psychology, University of Georgia, Athens, Georgia 30602. 343
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
344
GAIL M. WILLIAMSON AND RICHARD SCHULZ
dictors of psychological distress. In a sample of older adults with no history of clinical depression, we evaluated summary data from comprehensive medical examinations and subjects' own perceptions of their health status for relative ability to predict symptoms of depression. Consistent with previous research, we expected that objective (physician-rated) illness would explain substantial portions of the variance in depressive symptomatology. Moreover, given the strength of associations found in prior studies, we also expected that subjective (self-reported) illness would predict symptoms of depression beyond the effects of objectively assessed health. Taken together, health-related variables define some of the central factors that may contribute to symptoms of depression. However, as other researchers (e.g., Lewinsohn, Hoberman, & Rosenbaum, 1988) have proposed, it is unlikely that any factor is solely responsible for producing psychological distress. In addition to the stress associated with declining health, a variety of psychosocial factors are likely to increase the probability of experiencing depressed affect. Given the large body of literature indicating the importance of social support in mediating the relation between stressful events and psychological distress (e.g., Russell & Cutrona, 1991; also see Cohen & Wills, 1985; House, Landis, & Umberson, 1988, for reviews), we expected that social support would predict symptoms of depression after controlling for physical health status. We also included a category of additional "other worries" variables that preliminary research suggested might be related to depressed affect in the elderly (e.g., worries about becoming a burden to others and fears about personal safety). These variables were considered to be exploratory in nature, and our intent was to investigate their contribution to symptoms of depression beyond the effects of physical illness and social support.
Summary of Hypotheses and Goals On the basis of the results of prior research, we predicted that higher levels of depressive symptomatology would be associated with (a) objective (physician-rated) indicators of more physical illness, including symptoms, disease, impairment, and pain; (b) subjective (self-reported) indicators of more physical illness, including symptoms, disability, pain, and perceived overall health status; and (c) less social support. Beyond replicating earlier findings, we also made hypotheses regarding the relative contributions of each of these categories to explaining variance in symptoms of depression. Specifically, we predicted that subjective (self-reported) health would predict depressive symptomatology after controlling for the effects of objective (physician-rated) health and that social support would make an important contribution to depressive symptomatology beyond the effects of both objective and subjective physical illness. Finally, we predicted that more symptoms of depression would be found among those experiencing greater frequency of a new category of variables, "other worries." In addition to these predicted findings, we conducted other analyses to explore contributions to symptoms of depression made by other worries after controlling for physical health (both objective and subjective) and social support.
Method Data reported in this article are from the first wave of a four-panel longitudinal study. Three types of assessments were made: (a) medical evaluations by physicians and physician's assistants (PAs), (b) self-report data evaluating symptoms of depression and perceived physical health, and (c) demographic and psychosocial data relating to participants and their life circumstances.
Subjects Selection Criteria and Recruitment Procedure Subjects were recruited from two outpatient clinics at the University of Pittsburgh. These facilities provide comprehensive assessment, medical care, and case management to ambulatory adults from a broad social, cultural, economic, and educational base. Charts of patients scheduled for regular medical appointments were screened for eligibility on the following criteria: (a) 55 years of age or older; (b) community dwelling (i.e., not institutionalized); (c) no history of alcoholism; (d) a score of at least 25 out of 30 on the Folstein Mini-Mental State Examination (MMS; Folstein, Folstein, & McHugh, 1975); (e) no psychiatric history of major recurrent depression, schizophrenia, psychosis, organic mental disorder, or dementia; and (f) no single episode of major depression in the 6 months prior to recruitment. Following patient physical examinations, physicians and PAs provided data concerning the results of physical examinations and pain experienced by the patient. Psychosocial interviews were usually conducted in respondents' homes within 1 week after the clinic visit. Interviews took about 90 min to complete.
Participant Sample A total of 414 individuals met eligibility criteria. Of those, 230 (55.6%) agreed to participate. There were no significant differences in mean age or gender between those who agreed to participate and those who refused. The most commonly cited reason for refusing was being too ill to participate (37%), followed by time limitations and busy schedules (18%). Two individuals did not adequately complete the measure of depressive symptomatology and were excluded from all analyses, leaving a total of 228 subjects.
Measures Symptoms of Depression Subjects completed the Center for Epidemiologic Studies-Depression scale (CES-D; Radloff, 1977), a 20-item self-report instrument designed for use in the general population. The CES-D consists of items selected from previously validated scales (Beck Depression Inventory, Zung's Self-Rating Scale, and the Minnesota Multiphasic Personality Inventory depression scale) specifically to avoid the problem characteristic of some measures—placing too much emphasis on somatic factors that frequently characterize nondepressed older or disabled persons. Items were scored on a 4-point scale (0 to 3) describing frequency of occurrence during the previous week. Radloff reported high internal consistency, test-retest reliability, and validity. In the present sample, alpha for internal reliability was .89. Although we did not assess actual clinical depression, the CES-D has been shown to predict concurrent and future diagnosis of clinical depression (e.g., Lewinsohn et al., 1988; Roberts & Vernon, 1983; Rohde, Lewinsohn, Tilson, & Seeley, 1990; Schulberg, McClelland, & Burns, 1987) and to discriminate between community-residing older adults and those in inpatient psychiatric units (Himmelfarb &Murrell,
PHYSICAL ILLNESS AND SYMPTOMS OF DEPRESSION 1983). Scores of 16 and above are generally believed to indicate that individuals are at risk for clinical depression.
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Medical Evaluation—Physician-Rated Health Status Each participant's chart contained thorough medical histories and results of complete physical and neurologic examinations performed in a standardized manner according to established practice at the clinics. To keep the amount of data within manageable limits, assessment summaries were made in two categories: illnesses and their severity, and pain and discomfort associated with illness. Illnesses and their severity. Physicians formulated a complete list of medical diagnoses for each patient and rated severity of all diagnosed conditions. Three summary measures were derived from these data: (a) total symptoms represented a count of the presence or absence of 32 illness symptoms (e.g., fever, deafness, joint pain), (b) total diseases consisted of the number of diagnosed disease conditions, and (c) disease severity was derived by summing physician ratings of the severity of each diagnosed disease condition on scales of 0 to 3, with higher ratings indicating more severity. Clinic physicians also provided a fourth summary measure of patient health status. The Cumulative Illness Rating Scale (CIRS; B. S. Linn, Linn, & Gurel, 1968) yields estimates of physical impairment. On a scale of 0 (no impairment) to 4 (extremely severe impairment), physicians rated each patient's condition in 12 categories (e.g., cardiac, vascular, respiratory, neurologic). Ratings were summed to yield a total CIRS score. Pain and discomfort. Physicians also rated overall levels of pain and discomfort associated with patients' conditions. On scales of 0 (none) to 3 (much), three items asked (a) "In general, how much pain has been associated with these illnesses?" (b) "In your opinion, how much pain has the patient experienced in the last week as a result of these illnesses (independent of the patient's report)?" and (c) "In general, how much annoyance, as opposed to pain, would you think these illnesses have caused the patient?" On scales of 0 (no pain) to 5 (worst pain associated with these illnesses), physicians also rated, independent of the patient's report, (d) the most pain the patient had experienced, and (e) the amount of pain the patient had experienced in the past week. Scores on these five items were summed to yield a measure with standardized Cronbach's alpha of .94.
Self-Reported Physical Health Study participants provided data relevant to their perceived physical health status. Five categories of self-reported health were assessed: (a) subjective overall health, (b) objective health indicators, (c) symptoms, (d) pain and discomfort, and (e) areas of life affected by illness. Subjective overall health was measured with a single item asking subjects to rate their health on a scale of 1 (poor) to 5 (excellent). Objective self-reported health was assessed by summing patients' reports of the number of (a) hospitalization days and physician visits in the past 6 months, (b) disabilities and illnesses that limited activities in the past 12 months, and (c) other chronic health problems. Self-reported symptoms were measured using the 12-item somatization subscale of the Symptom Checklist 90 (SCL-90; Derogatis, Rickels, & Rock, 1976). The somatization scale includes items such as weakness, soreness, numbness, heavy feelings, headache, nausea, and faintness. Respondents indicated the degree to which each ailment had bothered them in the past month on a scale of 1 (not at all) to 5 (extremely). Two scores were obtained—a simple count of the number of symptoms indicated as being bothersome and the extent to which symptoms were bothersome. To measure pain and discomfort, a five-item index was constructed to assess general pain (0 = none, 3 = much), highest level of pain
345
associated with current illness (0 = no pain, 100 = worst pain you can imagine), pain during the past week (0 = none, 3 = much), highest level of pain in the past week (0 = no pain, 100 = worst pain you can imagine), and general annoyance or discomfort (0 = none, 3 = much). Cronbach's standardized alpha for this index was .89. Patients also reported the type and frequency of medications taken for pain and the numberof pain medications served as a secondary measure of discomfort. Perceptions of how health status affected subjects' lives were assessed in two ways. First, as a measure of disability, level of dependence on assistance from others was evaluated with the Activities of Daily Living Scale, derived from the Older Americans Resource and Services scales (OARS; Multidimensional Functional Assessment, 1978). Eighteen items assessed help needed in two categories: 7 items assessed activities of daily living (ADL; e.g., bathing, dressing, and eating), and 11 items assessed instrumental activities of daily living (IADL; e.g., managing money, doing laundry, and shopping for personal items). Each item was rated on a 4-point scale (0 = no help required, 3 = much help required). Second, to measure perceived activity restriction, respondents indicated the extent to which nine areas of activity (self-care, care of others, eating habits, sleeping habits, doing household chores, going shopping, visiting friends, working on hobbies, and maintaining friendships) were restricted by their illness or disability (0 = never or seldom did this, 4 = greatly restricted). Our prior research has shown these items to be highly interrelated (Cronbach's alpha = .89), and in the present study, Cronbach's alpha was .85.
Psychosocial Variables Standard demographic data (age, income, race, marital status, education, employment status, and religion) were collected. Additional psychosocial measures included health care concerns, financial worries, social support, and other worries. Health care concerns. Problems related to obtaining health care services were evaluated with three individual questions: (a) "Is transportation to and from the doctor or clinic a problem for you?" (1 = no problem at all, 4 = always a problem); (b) "How would you rate the amount of care you are getting?" (1 = much less than needed, 4 = more than I need); and (c) "In general, how satisfied are you with the medical care you have received for your latest health problem?" (1 = very dissatisfied, 4 = very satisfied). Financial worries. Four individual questions measured respondents' perceptions of financial difficulties: (a) "How adequate is your income to meet your needs?" (1 = much more than adequate, 5 = not at all adequate); (b) "How adequate are your insurance and financial resources for future health care needs?" (1 = inadequate, 3 = more than adequate); (c) "How much do you worry about being able to cover your health care expenses in the future?" (1 = don't worry at all, 3 = worry a great deal); and (d) "If you could afford it, what other services or care, if any, would you get?" (0 = no additional services needed, 1 = additional services needed). Social support. The construct of social support was assessed multidimensionally. First, satisfaction with social contacts was measured using a six-item scale previously found to predict depressive symptomatology in caregivers of Alzheimer's patients (Schulz, Williamson, Morycz, & Biegel, 1992). Items asked (a) how the number of people that participants felt close to had changed in the past 6 months (1 = increased, 3 = decreased, reverse scored); (b) satisfaction with amount of social contact (1 = very dissatisfied, 5 = very satisfied); (c) satisfaction with quality of social contact (scored same as Item b); (d) how much time participants would like to be spending with people they care about (1 = much less, 5 = much more, reverse scored); (e) how much socializing they were doing (1 = much less than I'd like, 5 = much more
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
346
GAIL M. WILLIAMSON AND RICHARD SCHULZ
than I'd like); and (f) how much help or support they were currently receiving (1 = much less than I need, 5 = much more than I need). Cronbach's alpha for this scale was .69. Although Items d, e, and f employed curvilinear rather than linear scales, few respondents indicated spending more time than they would like with people they care about (2.1%), doing more socializing than they would like (5.6%), or receiving more help or support than they needed (3.4%). Tests of deviation from linearity revealed no F values approaching significance (i.e., all ps > .05). Consequently, responses to these items were analyzed as linear functions. The dimension of perceived social support was measured using a six-item version of the Interpersonal Support Evaluation List (ISEL; Cohen, Mermelstein, Kamarck, & Hoberman, 1985). On a scale of 0 (definitely true) to 3 (definitely false), respondents rated these statements: (a) "When I feel lonely, there are several people I can talk to"; (b) "I often meet or talk with family or friends"; (c) "If I were sick, I could easily find someone to help me with my daily chores"; (d) "When I need suggestions on how to deal with a personal problem, I know someone I can turn to"; (e) "If I had to go out of town for a few weeks, it would be difficult to find someone who would look after my house or apartment" (reverse scored); and (0 "There is at least one person I know whose advice I really trust." Cronbach's alpha was .73. Social exits were investigated using a life events instrument that examines 15 events involving the loss or disruption of important relationships with others (Cohen, Tyrrell, & Smith, 1991). These include moving, death or serious illness of a close other, separation or divorce, relationships that ended or became significantly worse, and other events (e.g., loss of job) that might affect interpersonal relationships. Participants were asked to indicate whether each event had occurred within the past year (0 = no, 1 = yes). Affirmative responses were summed to yield the number of social exits experienced. Two additional social support items were scored individually. To assess willingness to seek help from others, subjects were asked, "In general, how likely are you to ask people you know for help or support?" (1 = very unlikely, 5 = very likely). To measure degree of importance subjects placed on social contact, they were asked, "How important would you say it is for you to get together with people?" (1 = not important, 5 = very important). Other worries. We devised a list of 13 other worries, based on evidence obtained in preliminary work with elderly populations (e.g., becoming a burden to others; see Table 2 for a complete list). Respondents selected as many as 3 concerns that had been difficult for them to face in the past month. Responses for each item were coded as 0 (not difficult) or 1 (difficult).
Statistical Analyses We conducted analyses in four stages. First, the sample was described in terms of CES-D scores and demographic variables. Second, we evaluated relations between indicators of physical illness (both physician-rated and self-reported) and depressive symptomatology. In the third analysis stage, we evaluated relations between sets of psychosocial factors (i.e., health care concerns, financial worries, social support, and other worries) and CES-D scores. The fourth stage consisted of analyses aimed at documenting the importance of these factors in explaining variance in symptoms of depression beyond the effects of physical illness. A large number of analyses (slightly more than 100) were conducted to obtain the reported results. To control for Type I error, only alphasof at least p < .01 are considered significant. For some analyses, incomplete or missing data resulted in n less than 228 (minimum n in any analysis = 210).
Results
Sample Characteristics Participants ranged in age from 59 to 95 years (M = 72). Modal yearly household income was between $5,000 and $10,000. Of the total sample, 68.9% were women. Approximately two thirds of the sample were White; all remaining subjects were Black. One third were married, and an additional 40% were widows or widowers. Two thirds (66.0%) had at least a high school education. Almost one third of the sample were Catholic and more than one half were Protestant. Not surprisingly, given the age of this group, most (60.9%) were retired. Mean score for the CES-D was 10.57, indicating levels of depressive symptomatology substantially higher than population means for similarly aged individuals (M= 7.4) reported by Berkman et al. (1986). Of the total sample, 23.7% (« = 54) were at risk for developing clinical depression, with CES-D scores of 16 or higher. Symptoms of Depression and Physical Health Physician-Rated Health Status Mean scores and standard deviations for each of the physician-rated variables are shown in Table 1, as are correlations between CES-D scores and medical summary variables. Patients evaluated as having more physical illness symptoms and greater physical impairment reported more symptoms of depression. Total diseases, disease severity, and physician-rated pain were not related to CES-D scores. Self-Reported Physical Health Means and standard deviations for self-reported health measures are reported in Table 1 along with correlations between
Table 1
Physical Health Variables: Means and Correlates of Symptoms of Depression Variable Physician-rated health Total symptoms Total diseases Disease severity CIRS Pain Self-reported health Subjective health Objective health Total symptoms Severity of symptoms Pain Pain medications ADL IADL Activity restriction
M
SD
7.12 6.32 4.10 6.57 6.52
4.71 2.51 3.07 3.16 5.40
.35** .12 .08 .21** .05
2.97 9.53 4.32 20.77 82.68 0.71 0.73 3.50 13.25
1.05 10.05 2.91 7.51 65.18 0.84 2.65 5.72 6.27
-.36** .18* .34* .35* .30* .33* .08 .23* .36*
Note. CIRS = Cumulative Illness Rating Scale (B. S. Linn, Linn, & Gurel, 1968); ADL = activities of daily living; IADL = instrumental activities of dairy living. *p
Psychology and Aging 1992. Vol.7. No. 3, 343-351
Physical Illness and Symptoms of Depression Among Elderly Outpatients Gail M. Williamson
Richard Schulz University of Pittsburgh
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
University of Georgia
Elderly outpatients were assessed to clarify relations between symptoms of depression and physical illness, disability, pain, and selected psychosocial variables. Three types of assessments were made: (a) medical evaluations by physicians, (b) self-reported symptoms of depression and physical health, and (c) demographic and psychosocial data relating to participants' life circumstances. Both objective (physician-rated illness symptoms) and subjective (self-reported health, activity restriction, and use of pain medications) indicators of health accounted for independent variance in symptoms of depression. After controlling for these factors, additional variance was explained by health-related concerns (e.g., health care expenses, service needs), social support, and "other worries" (e.g., feeling useless, becoming a burden to others).
mano & Turner, 1985; Roy, Thomas, & Matas, 1984). Recently, Parmelee, Katz, and Lawton (1991) found significant associations between pain and depression in a sample of institutionalized elderly. Moreover, although depression was correlated with physical illness severity and functional disability, these correlations did not account for the association between depression and pain. In sum, there is abundant evidence indicating that physical health variables (e.g., illness, disability, and pain) are related to increased psychological distress among the elderly. However, the exact nature of the association remains unclear. In particular, both medically diagnosed and self-reported illness have been shown to be related to psychological distress. Although the results of studies using subjective (self-report) measures of health (e.g., Bolla-Wilson & Bleecker, 1989; Palinkas et al., 1990; Phifer & Murrell, 1986; Revicki & Mitchell, 1990) are consistent with those using objective (e.g., physician-rated) measures, there are reasons to suspect that subjective health may be a better predictor of psychological well-being than is objective health. Recently, Pearlman and Uhlmann (1991) found that quality of life among elderly outpatients was more strongly related to subjective perceptions of health than to the more objective (but still self-report) measure of health care utilization. Such findings are problematic because subjective measures of health may be confounded by psychological distress (e.g., Cohen & Williamson, 1988,1991; Schulz, Visintainer, & Williamson, 1990). In particular, individuals who are more psychologically distressed may be more prone to report being in poorer physical health or to exaggerate reports of health care utilization. If this is the case, then the association between actual health status and depressed affect may be weaker than previously believed. Another possibility is that objective and subjective health contribute to psychological distress independently. In other words, it may be that the documented presence of illness per se leads to declines in affect and that negative perceptions of one's own health status further exacerbate this effect. As yet, few studies have compared objective, physician-assessed health status with subjective, self-reported health as pre-
Although the prevalence of major depression is relatively low among the elderly, a substantial proportion report high levels of depressive symptomatology (Blazer, 1989; Palinkas, Wingard, & Barrett-Connor, 1990). For example, two population studies (Blazer & Williams, 1980; National Institute on Aging, 1986) found that 15% of older adults met criteria for being at risk for clinical depression. A factor repeatedly shown to be associated with affect disturbance in the elderly is the presence of physical illness (e.g., Cassileth et al., 1984; LaRue, Dessonville, & Jarvick, 1985; Pfeiffer & Busse, 1973; Stenback, 1980). In a crossnational study of elderly residents of London and New \brk, Gurland et al. (1983) reported that degree of physical illness was the most consistent correlate of pervasive depression (i.e., needing clinical attention). On the basis of these results, Gurland et al. concluded that "physical illness, disability and dependence [are] probably the major determinants of depression in the elderly" (p. 245). Other research supports this conclusion (e.g., Blazer & Williams, 1980; Cheah & Beard, 1980; Conlin & Fennell, 1983; Roth & Kay, 1956). When biological factors have been ruled out as causes of affect disturbance, speculation about mediating mechanisms has often focused on disability. For example, greater functional incapacity in rheumatoid arthritics (Moos, 1964) and inability to perform normal activities in cancer patients (Cassileth et al., 1984) have been shown to be related to poorer mental health. M. Linn, Hunter, and Harris (1980) reported that, after controlling for level of physical disability, physical illness no longer predicted degree of depression. Gurland et al. (1983) suggested that physical disability may be the primary factor accounting for depression among the physically ill. Another potential causal agent is pain. Chronic pain patients of all adult ages show increased rates of depression (e.g., Ro-
This research was supported by Grant RO1 MH41887 from the National Institute of Mental Health (Richard Schulz, principal investigator). Correspondence concerning this article should be addressed to Gail M. Williamson, Department of Psychology, University of Georgia, Athens, Georgia 30602. 343
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
344
GAIL M. WILLIAMSON AND RICHARD SCHULZ
dictors of psychological distress. In a sample of older adults with no history of clinical depression, we evaluated summary data from comprehensive medical examinations and subjects' own perceptions of their health status for relative ability to predict symptoms of depression. Consistent with previous research, we expected that objective (physician-rated) illness would explain substantial portions of the variance in depressive symptomatology. Moreover, given the strength of associations found in prior studies, we also expected that subjective (self-reported) illness would predict symptoms of depression beyond the effects of objectively assessed health. Taken together, health-related variables define some of the central factors that may contribute to symptoms of depression. However, as other researchers (e.g., Lewinsohn, Hoberman, & Rosenbaum, 1988) have proposed, it is unlikely that any factor is solely responsible for producing psychological distress. In addition to the stress associated with declining health, a variety of psychosocial factors are likely to increase the probability of experiencing depressed affect. Given the large body of literature indicating the importance of social support in mediating the relation between stressful events and psychological distress (e.g., Russell & Cutrona, 1991; also see Cohen & Wills, 1985; House, Landis, & Umberson, 1988, for reviews), we expected that social support would predict symptoms of depression after controlling for physical health status. We also included a category of additional "other worries" variables that preliminary research suggested might be related to depressed affect in the elderly (e.g., worries about becoming a burden to others and fears about personal safety). These variables were considered to be exploratory in nature, and our intent was to investigate their contribution to symptoms of depression beyond the effects of physical illness and social support.
Summary of Hypotheses and Goals On the basis of the results of prior research, we predicted that higher levels of depressive symptomatology would be associated with (a) objective (physician-rated) indicators of more physical illness, including symptoms, disease, impairment, and pain; (b) subjective (self-reported) indicators of more physical illness, including symptoms, disability, pain, and perceived overall health status; and (c) less social support. Beyond replicating earlier findings, we also made hypotheses regarding the relative contributions of each of these categories to explaining variance in symptoms of depression. Specifically, we predicted that subjective (self-reported) health would predict depressive symptomatology after controlling for the effects of objective (physician-rated) health and that social support would make an important contribution to depressive symptomatology beyond the effects of both objective and subjective physical illness. Finally, we predicted that more symptoms of depression would be found among those experiencing greater frequency of a new category of variables, "other worries." In addition to these predicted findings, we conducted other analyses to explore contributions to symptoms of depression made by other worries after controlling for physical health (both objective and subjective) and social support.
Method Data reported in this article are from the first wave of a four-panel longitudinal study. Three types of assessments were made: (a) medical evaluations by physicians and physician's assistants (PAs), (b) self-report data evaluating symptoms of depression and perceived physical health, and (c) demographic and psychosocial data relating to participants and their life circumstances.
Subjects Selection Criteria and Recruitment Procedure Subjects were recruited from two outpatient clinics at the University of Pittsburgh. These facilities provide comprehensive assessment, medical care, and case management to ambulatory adults from a broad social, cultural, economic, and educational base. Charts of patients scheduled for regular medical appointments were screened for eligibility on the following criteria: (a) 55 years of age or older; (b) community dwelling (i.e., not institutionalized); (c) no history of alcoholism; (d) a score of at least 25 out of 30 on the Folstein Mini-Mental State Examination (MMS; Folstein, Folstein, & McHugh, 1975); (e) no psychiatric history of major recurrent depression, schizophrenia, psychosis, organic mental disorder, or dementia; and (f) no single episode of major depression in the 6 months prior to recruitment. Following patient physical examinations, physicians and PAs provided data concerning the results of physical examinations and pain experienced by the patient. Psychosocial interviews were usually conducted in respondents' homes within 1 week after the clinic visit. Interviews took about 90 min to complete.
Participant Sample A total of 414 individuals met eligibility criteria. Of those, 230 (55.6%) agreed to participate. There were no significant differences in mean age or gender between those who agreed to participate and those who refused. The most commonly cited reason for refusing was being too ill to participate (37%), followed by time limitations and busy schedules (18%). Two individuals did not adequately complete the measure of depressive symptomatology and were excluded from all analyses, leaving a total of 228 subjects.
Measures Symptoms of Depression Subjects completed the Center for Epidemiologic Studies-Depression scale (CES-D; Radloff, 1977), a 20-item self-report instrument designed for use in the general population. The CES-D consists of items selected from previously validated scales (Beck Depression Inventory, Zung's Self-Rating Scale, and the Minnesota Multiphasic Personality Inventory depression scale) specifically to avoid the problem characteristic of some measures—placing too much emphasis on somatic factors that frequently characterize nondepressed older or disabled persons. Items were scored on a 4-point scale (0 to 3) describing frequency of occurrence during the previous week. Radloff reported high internal consistency, test-retest reliability, and validity. In the present sample, alpha for internal reliability was .89. Although we did not assess actual clinical depression, the CES-D has been shown to predict concurrent and future diagnosis of clinical depression (e.g., Lewinsohn et al., 1988; Roberts & Vernon, 1983; Rohde, Lewinsohn, Tilson, & Seeley, 1990; Schulberg, McClelland, & Burns, 1987) and to discriminate between community-residing older adults and those in inpatient psychiatric units (Himmelfarb &Murrell,
PHYSICAL ILLNESS AND SYMPTOMS OF DEPRESSION 1983). Scores of 16 and above are generally believed to indicate that individuals are at risk for clinical depression.
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Medical Evaluation—Physician-Rated Health Status Each participant's chart contained thorough medical histories and results of complete physical and neurologic examinations performed in a standardized manner according to established practice at the clinics. To keep the amount of data within manageable limits, assessment summaries were made in two categories: illnesses and their severity, and pain and discomfort associated with illness. Illnesses and their severity. Physicians formulated a complete list of medical diagnoses for each patient and rated severity of all diagnosed conditions. Three summary measures were derived from these data: (a) total symptoms represented a count of the presence or absence of 32 illness symptoms (e.g., fever, deafness, joint pain), (b) total diseases consisted of the number of diagnosed disease conditions, and (c) disease severity was derived by summing physician ratings of the severity of each diagnosed disease condition on scales of 0 to 3, with higher ratings indicating more severity. Clinic physicians also provided a fourth summary measure of patient health status. The Cumulative Illness Rating Scale (CIRS; B. S. Linn, Linn, & Gurel, 1968) yields estimates of physical impairment. On a scale of 0 (no impairment) to 4 (extremely severe impairment), physicians rated each patient's condition in 12 categories (e.g., cardiac, vascular, respiratory, neurologic). Ratings were summed to yield a total CIRS score. Pain and discomfort. Physicians also rated overall levels of pain and discomfort associated with patients' conditions. On scales of 0 (none) to 3 (much), three items asked (a) "In general, how much pain has been associated with these illnesses?" (b) "In your opinion, how much pain has the patient experienced in the last week as a result of these illnesses (independent of the patient's report)?" and (c) "In general, how much annoyance, as opposed to pain, would you think these illnesses have caused the patient?" On scales of 0 (no pain) to 5 (worst pain associated with these illnesses), physicians also rated, independent of the patient's report, (d) the most pain the patient had experienced, and (e) the amount of pain the patient had experienced in the past week. Scores on these five items were summed to yield a measure with standardized Cronbach's alpha of .94.
Self-Reported Physical Health Study participants provided data relevant to their perceived physical health status. Five categories of self-reported health were assessed: (a) subjective overall health, (b) objective health indicators, (c) symptoms, (d) pain and discomfort, and (e) areas of life affected by illness. Subjective overall health was measured with a single item asking subjects to rate their health on a scale of 1 (poor) to 5 (excellent). Objective self-reported health was assessed by summing patients' reports of the number of (a) hospitalization days and physician visits in the past 6 months, (b) disabilities and illnesses that limited activities in the past 12 months, and (c) other chronic health problems. Self-reported symptoms were measured using the 12-item somatization subscale of the Symptom Checklist 90 (SCL-90; Derogatis, Rickels, & Rock, 1976). The somatization scale includes items such as weakness, soreness, numbness, heavy feelings, headache, nausea, and faintness. Respondents indicated the degree to which each ailment had bothered them in the past month on a scale of 1 (not at all) to 5 (extremely). Two scores were obtained—a simple count of the number of symptoms indicated as being bothersome and the extent to which symptoms were bothersome. To measure pain and discomfort, a five-item index was constructed to assess general pain (0 = none, 3 = much), highest level of pain
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associated with current illness (0 = no pain, 100 = worst pain you can imagine), pain during the past week (0 = none, 3 = much), highest level of pain in the past week (0 = no pain, 100 = worst pain you can imagine), and general annoyance or discomfort (0 = none, 3 = much). Cronbach's standardized alpha for this index was .89. Patients also reported the type and frequency of medications taken for pain and the numberof pain medications served as a secondary measure of discomfort. Perceptions of how health status affected subjects' lives were assessed in two ways. First, as a measure of disability, level of dependence on assistance from others was evaluated with the Activities of Daily Living Scale, derived from the Older Americans Resource and Services scales (OARS; Multidimensional Functional Assessment, 1978). Eighteen items assessed help needed in two categories: 7 items assessed activities of daily living (ADL; e.g., bathing, dressing, and eating), and 11 items assessed instrumental activities of daily living (IADL; e.g., managing money, doing laundry, and shopping for personal items). Each item was rated on a 4-point scale (0 = no help required, 3 = much help required). Second, to measure perceived activity restriction, respondents indicated the extent to which nine areas of activity (self-care, care of others, eating habits, sleeping habits, doing household chores, going shopping, visiting friends, working on hobbies, and maintaining friendships) were restricted by their illness or disability (0 = never or seldom did this, 4 = greatly restricted). Our prior research has shown these items to be highly interrelated (Cronbach's alpha = .89), and in the present study, Cronbach's alpha was .85.
Psychosocial Variables Standard demographic data (age, income, race, marital status, education, employment status, and religion) were collected. Additional psychosocial measures included health care concerns, financial worries, social support, and other worries. Health care concerns. Problems related to obtaining health care services were evaluated with three individual questions: (a) "Is transportation to and from the doctor or clinic a problem for you?" (1 = no problem at all, 4 = always a problem); (b) "How would you rate the amount of care you are getting?" (1 = much less than needed, 4 = more than I need); and (c) "In general, how satisfied are you with the medical care you have received for your latest health problem?" (1 = very dissatisfied, 4 = very satisfied). Financial worries. Four individual questions measured respondents' perceptions of financial difficulties: (a) "How adequate is your income to meet your needs?" (1 = much more than adequate, 5 = not at all adequate); (b) "How adequate are your insurance and financial resources for future health care needs?" (1 = inadequate, 3 = more than adequate); (c) "How much do you worry about being able to cover your health care expenses in the future?" (1 = don't worry at all, 3 = worry a great deal); and (d) "If you could afford it, what other services or care, if any, would you get?" (0 = no additional services needed, 1 = additional services needed). Social support. The construct of social support was assessed multidimensionally. First, satisfaction with social contacts was measured using a six-item scale previously found to predict depressive symptomatology in caregivers of Alzheimer's patients (Schulz, Williamson, Morycz, & Biegel, 1992). Items asked (a) how the number of people that participants felt close to had changed in the past 6 months (1 = increased, 3 = decreased, reverse scored); (b) satisfaction with amount of social contact (1 = very dissatisfied, 5 = very satisfied); (c) satisfaction with quality of social contact (scored same as Item b); (d) how much time participants would like to be spending with people they care about (1 = much less, 5 = much more, reverse scored); (e) how much socializing they were doing (1 = much less than I'd like, 5 = much more
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GAIL M. WILLIAMSON AND RICHARD SCHULZ
than I'd like); and (f) how much help or support they were currently receiving (1 = much less than I need, 5 = much more than I need). Cronbach's alpha for this scale was .69. Although Items d, e, and f employed curvilinear rather than linear scales, few respondents indicated spending more time than they would like with people they care about (2.1%), doing more socializing than they would like (5.6%), or receiving more help or support than they needed (3.4%). Tests of deviation from linearity revealed no F values approaching significance (i.e., all ps > .05). Consequently, responses to these items were analyzed as linear functions. The dimension of perceived social support was measured using a six-item version of the Interpersonal Support Evaluation List (ISEL; Cohen, Mermelstein, Kamarck, & Hoberman, 1985). On a scale of 0 (definitely true) to 3 (definitely false), respondents rated these statements: (a) "When I feel lonely, there are several people I can talk to"; (b) "I often meet or talk with family or friends"; (c) "If I were sick, I could easily find someone to help me with my daily chores"; (d) "When I need suggestions on how to deal with a personal problem, I know someone I can turn to"; (e) "If I had to go out of town for a few weeks, it would be difficult to find someone who would look after my house or apartment" (reverse scored); and (0 "There is at least one person I know whose advice I really trust." Cronbach's alpha was .73. Social exits were investigated using a life events instrument that examines 15 events involving the loss or disruption of important relationships with others (Cohen, Tyrrell, & Smith, 1991). These include moving, death or serious illness of a close other, separation or divorce, relationships that ended or became significantly worse, and other events (e.g., loss of job) that might affect interpersonal relationships. Participants were asked to indicate whether each event had occurred within the past year (0 = no, 1 = yes). Affirmative responses were summed to yield the number of social exits experienced. Two additional social support items were scored individually. To assess willingness to seek help from others, subjects were asked, "In general, how likely are you to ask people you know for help or support?" (1 = very unlikely, 5 = very likely). To measure degree of importance subjects placed on social contact, they were asked, "How important would you say it is for you to get together with people?" (1 = not important, 5 = very important). Other worries. We devised a list of 13 other worries, based on evidence obtained in preliminary work with elderly populations (e.g., becoming a burden to others; see Table 2 for a complete list). Respondents selected as many as 3 concerns that had been difficult for them to face in the past month. Responses for each item were coded as 0 (not difficult) or 1 (difficult).
Statistical Analyses We conducted analyses in four stages. First, the sample was described in terms of CES-D scores and demographic variables. Second, we evaluated relations between indicators of physical illness (both physician-rated and self-reported) and depressive symptomatology. In the third analysis stage, we evaluated relations between sets of psychosocial factors (i.e., health care concerns, financial worries, social support, and other worries) and CES-D scores. The fourth stage consisted of analyses aimed at documenting the importance of these factors in explaining variance in symptoms of depression beyond the effects of physical illness. A large number of analyses (slightly more than 100) were conducted to obtain the reported results. To control for Type I error, only alphasof at least p < .01 are considered significant. For some analyses, incomplete or missing data resulted in n less than 228 (minimum n in any analysis = 210).
Results
Sample Characteristics Participants ranged in age from 59 to 95 years (M = 72). Modal yearly household income was between $5,000 and $10,000. Of the total sample, 68.9% were women. Approximately two thirds of the sample were White; all remaining subjects were Black. One third were married, and an additional 40% were widows or widowers. Two thirds (66.0%) had at least a high school education. Almost one third of the sample were Catholic and more than one half were Protestant. Not surprisingly, given the age of this group, most (60.9%) were retired. Mean score for the CES-D was 10.57, indicating levels of depressive symptomatology substantially higher than population means for similarly aged individuals (M= 7.4) reported by Berkman et al. (1986). Of the total sample, 23.7% (« = 54) were at risk for developing clinical depression, with CES-D scores of 16 or higher. Symptoms of Depression and Physical Health Physician-Rated Health Status Mean scores and standard deviations for each of the physician-rated variables are shown in Table 1, as are correlations between CES-D scores and medical summary variables. Patients evaluated as having more physical illness symptoms and greater physical impairment reported more symptoms of depression. Total diseases, disease severity, and physician-rated pain were not related to CES-D scores. Self-Reported Physical Health Means and standard deviations for self-reported health measures are reported in Table 1 along with correlations between
Table 1
Physical Health Variables: Means and Correlates of Symptoms of Depression Variable Physician-rated health Total symptoms Total diseases Disease severity CIRS Pain Self-reported health Subjective health Objective health Total symptoms Severity of symptoms Pain Pain medications ADL IADL Activity restriction
M
SD
7.12 6.32 4.10 6.57 6.52
4.71 2.51 3.07 3.16 5.40
.35** .12 .08 .21** .05
2.97 9.53 4.32 20.77 82.68 0.71 0.73 3.50 13.25
1.05 10.05 2.91 7.51 65.18 0.84 2.65 5.72 6.27
-.36** .18* .34* .35* .30* .33* .08 .23* .36*
Note. CIRS = Cumulative Illness Rating Scale (B. S. Linn, Linn, & Gurel, 1968); ADL = activities of daily living; IADL = instrumental activities of dairy living. *p
