Psychological Disorders and Distress in Older Primary Care Patients: A Comparison of Older and Younger Samples

Transcription

1 Psychological Disorders and Distress in Older Primary Care Patients: A Comparison of Older and Younger Samples JOSHUA KLAPOW, PHD, KURT KROENKE, MD, TRUDI HORTON, PHD, STEVEN SCHMIDT, BA, ROBERT SPITZER, MD, AND JANET B. W. WILLIAMS, DSW Background: Community studies have documented prevalence rates of psychological disorders among older individuals. Further, a growing number of studies have examined depression in older medical patients. However, little is known about the prevalence of a broad range of psychological disorders and psychosocial stressors among older primary care patients. The purpose of the present study was to characterize psychological disorders and psychosocial stressors in older primary care patients and identify differences with younger patients. Methods: Descriptive survey; criterion standard. Five hundred thirty-four patients 65 years and older and 2466 patients less than 65 years old recruited from eight primary care sites. The Patient Health Questionnaire (PHQ) was employed to assess major depressive disorder, other depressive disorder, panic disorder, other anxiety disorder, probable alcohol abuse/dependence, somatoform disorder, bulimia nervosa, and binge eating disorder. Common psychosocial stressors were also assessed. Patient-reported health status was measured by the Medical Outcomes Study Short Form 20 (SF-20). Results: Older patients were much less likely than younger patients to have a psychological disorder (5% vs. 17%). Also, older patients had significantly less severe psychological symptom (4.7 vs. 8.0) and psychosocial stressor (2.3 vs. 4.7) scores. Worrying about health (10%), weight (9%), and a recent bad event (8%) were the most common stressors among the older group. Like younger patients, older patients who suffered from psychological symptoms and disorders experienced substantial functional impairment. Conclusions: Prevalence rates of psychological disorders and psychosocial stressors differ greatly between younger and older primary care patients and, somewhat contrary to clinical intuition, are lower among older patients. Key words: psychological distress, primary care, elderly, health status. PHQ Patient Health Questionnaire; SF-20 Medical Outcomes Study Short-Form 20. INTRODUCTION Chronic medical conditions are common among older patients, although often a direct relationship between presenting symptoms and an underlying medical illness is not present (1). Indeed, at least one third of presenting symptoms lack a clear-cut physical etiology (2 5), and several studies have identified psychological and psychosocial factors as prominent contributors to symptom manifestation (2 6). The From the Department of Psychology (J.K., S.S.), University of Alabama at Birmingham, Birmingham, AL; Department of Health Care Organization and Policy (J.K.), University of Alabama at Birmingham, Birmingham, AL; Center for Outcomes and Effectiveness Research and Education (J.K., T.H.), University of Alabama at Birmingham, Birmingham, AL; Regenstrief Institute for Health Care and Department of Medicine (K.K.), Indiana University, Indianapolis, IN; and Biometrics Research Department (R.S., J.B.W.W.), New York State Psychiatric Institute and Department of Psychiatry, Columbia University, New York, NY. Address reprint requests to: Joshua Klapow, the University of Alabama at Birmingham, 330 Ryals Public Health Building, 1665 University Boulevard, Birmingham, AL jklapow@uab.edu Received for publication April 20, 2001; revision received August 14, DOI: /01.PSY C3 spectrum of psychological disorders and symptoms among general primary care populations and the impact on functional status and health care utilization have been well documented (7 10). Further, there is a growing literature documenting prevalence rates of depression in older patients across a variety of health care settings (11 19); however, only community-based studies such as the Epidemiologic Catchment Area Study have examined a broad spectrum of psychological disorders in both older and younger individuals (20 22). Therefore, beyond the diagnosis of depression, little is known about the range and prevalence of psychological symptoms and disorders among older patients in the primary care setting (2 6, 11, 12, 15 19). Moreover, studies have yet to systematically examine the prevalence of a broad array of psychosocial stressors among older primary care patients. Older primary care patients are a particularly vulnerable group for the misdiagnosis and mismanagement of psychological symptoms and psychosocial stressors. Research has suggested that older patients may be more likely than younger patients to report physical symptoms rather than emotional symptoms when psychological distress is present (23), making it difficult to differentiate the origin of somatic complaints (ie, disease progression vs. distress). Studies have also documented a greater preference of older patients (relative to younger patients) to seek care for psychological problems from a primary care provider rather than a mental health specialist (24 26). Given these factors, we sought to address the following questions: /02/ Copyright 2002 by the American Psychosomatic Society 635

2 J. C. KLAPOW et al. 1. What is the prevalence of psychological disorders in older primary care patients and does it differ from younger patients? 2. What are the most common psychosocial stressors among older primary care patients and do they differ from younger patients? 3. Are psychological disorders in older primary care patients associated with somatic complaints, health-related quality of life, and use of health care services? METHODS Sites and Selection of Subjects All data reported in the present study were collected previously as part of a large-scale validation study for the Patient Health Questionnaire (PHQ). Details of the study including subject recruitment and retention have been previously reported (10). Briefly, the study was conducted at eight primary care sites (five general internal medicine and three family practice). The institutional review board of each site approved the study protocol. From May 1997 to November 1998, 3890 patients, 18 years or older, who presented to the centers for medical care were approached to participate in the study. Of the patients, 190 declined to participate, 266 started but did not complete the questionnaire, and 434 questionnaires were not entered into the data set because either more than one page was not completed or inadequate data were available. This resulted in the 3000 cases reported here (1578 family practice, 1422 general internal medicine). All sites used one of two subject selection methods to minimize sampling bias: either consecutive patients for a given clinic session or every nth patient until the intended quota for that session was achieved. From this data set, two groups were created (Table 1). Older patients were those 65 years or more (N 534), and younger patients were between the ages of 18 and 64 (N 2466). Measures The Patient Health Questionnaire (10) is a four-page self-administered questionnaire derived from the PRIME-MD (Primary Care Evaluation of Mental Disorders) (7). The PHQ assesses eight of the most common disorders in the primary care setting. The disorders are divided into threshold disorders (disorders that correspond to specific DSM-IV diagnoses: major depressive disorder, panic disorder, other anxiety disorder, and bulimia nervosa) and subthreshold disorders (disorders for which criteria encompass fewer symptoms than are required for any specific DSM-IV diagnoses: other depressive disorder, probable alcohol abuse/dependence, somatoform and binge eating disorders). Individuals who endorse symptoms that do not meet criteria for threshold or subthreshold disorders were considered to be symptom screen positive. In this study, the data from the questionnaire were entered into a computer program, which then applied the diagnostic algorithms (written in SPSS 8.0 for Windows). The computer program does not include the diagnosis of somatoform disorder because this diagnosis requires a clinical judgment regarding the adequacy of a biological explanation for physical symptoms that the patient has noted. In addition to the 8 psychiatric diagnoses, the PHQ assesses concern about 10 common psychosocial stressors (eg, financial status, family relationships, work, health) on a three-point scale (not bothered, bothered a little, bothered a lot). Also, summary scores combining frequency and severity are derived for somatic symptoms TABLE 1. Characteristics of Older and Young Primary Care Patients Older ( 65) (n 534) Younger ( 65) (n 2466) Age, mean (SD) 73 (6.30)* 40 (12.32) Women, % 60** 68 Race, % minority 31** 24 High school education or 73** 84 greater, % Physical conditions, % Hypertension 52.6** 18.1 Arthritis 29.0** 6.4 Cardiac 21.5** 4.7 Diabetes 12.4** 6.6 Pulmonary 10.1** 6.3 Cancer 5.8** 1.4 Renal 2.8* 0.8 Liver Other Number of physical 1.7 (1.2)** 0.8 (0.9) conditions, mean (SD) PHQ Somatic Symptom 6.3 (4.7)** 7.5 (5.2) Severity, mean (SD) PHQ Psychological Symptom 4.4 (5.6)** 8.0 (8.6) Severity, mean (SD) PHQ Psychosocial Stressor 2.3 (2.3)** 4.7 (3.5) Severity, mean (SD) Clinic visits in past 3 months, 1.2 (2.7)* 1.5 (2.7) mean (SD) Disability days in past 3 months, mean (SD) 3.0 (10.4)** 6.2 (15.5) * Significant difference from the younger group, p.05; ** significant difference from the younger group, p.01. (13 commonly presented symptoms, referred to as Somatic Symptom Severity), psychological symptoms (Psychological Symptom Severity), and psychosocial stressors (Psychosocial Stressor Severity). Finally, a single item (referred to as perceived difficulty) asks patients who have checked off any problems on the questionnaire, How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people? The four response categories range from not difficult at all to extremely difficult. In addition to the PHQ, each patient completed the Medical Outcomes Study Short-Form General Health Survey (SF-20) (27). The SF-20 measures health-related quality of life in six dimensions (all scores range from 0 to 100, 100 best health). Validity of the PHQ was established by examining the consistency between PHQ diagnoses and diagnoses derived by a phone interview by a mental health professional (MHP) in a mixed sample of older and younger primary care patients (N 550). Overall, agreement between PHQ diagnoses and MHP diagnoses was good (kappa 0.65) (10). When older and younger patients are separated, agreement between PHQ diagnoses and MHP diagnoses does not differ significantly by age group: the kappas for PHQ-MHP agreement for diagnosis of any psychological disorder among older compared with younger patients are.59 and.64, respectively; for mood disorders, they are.50 and.58; for anxiety disorders, they are.56 and.63; and for alcohol disorders, they are.79 and.60. There were no older patients with an eating disorder. These findings support the validity of the PHQ in both younger and older patient samples. 636

3 DISTRESS IN PRIMARY CARE PATIENTS Data Collection Patients. Before seeing the physician, all patients completed the PHQ. Additionally, they completed items regarding physician visits and disability days during the past 3 months, their comfort with answering the PHQ questions, and how valuable they believed the PHQ would be to their doctor in understanding and treating the problems they were having. Physicians. A total of 62 physicians participated in the study (21 general internal medicine; 41 family practice, 19 of whom were family practice residents). Their mean age was 37 years (SD 6.5), and 63% were male. All patients participating in the study were seen by one of the 62 physicians. After evaluating each patient but before reviewing the PHQ, the physician noted whether the patient was new or established, his or her knowledge of any current mental disorders, and types of current physical disorders (hypertension, heart disease, diabetes, liver disease, renal disease, arthritis, pulmonary disease, cancer, or other). The physician then reviewed the PHQ and asked any additional questions necessary to clarify responses on the questionnaire. Also noted were any treatments or referrals for mental disorders that were being initiated on this visit or being planned for initiation in the future. Details regarding types of treatments and referrals are reported in detail elsewhere (10). In the present study, all psychological symptoms and disorders reported were derived from patient responses to the PHQ, not physician diagnoses. Statistical Analyses Because data in the current study had been collected previously and examined in a validation study, findings presented in the current study were derived as post hoc analyses. All analyses were performed with SPSS PC 8.0. All categorical variables were evaluated using chi-square analyses. Comparisons of older and younger patients across continuous variables were conducted using t tests. Examination of the relationship between age and psychological symptoms was conducted with linear regression. Comparisons of diagnostic status were conducted using analysis of covariance with age and number of physical conditions as covariates. Follow-up comparisons were conducted using Tukey s pairwise comparison test. Approximately 4% of the 54 questionnaire items that all subjects were asked to complete had missing data. Missing data for the SF-20 scales were determined as in the original PHQ validation study (10). This resulted in missing data on 4% to 9% of the subjects for the different scales. For 4% of the questionnaires, physician data were absent. RESULTS Table 1 presents demographics, comorbidities, symptoms, and health care utilization for older and younger patients. As highlighted in Table 1, the older sample was, on average, 73 years old, predominately Caucasian, and high-school educated. The younger sample was, on average, 40 years old and also predominately Caucasian and high-school educated. While the mean number of physical conditions was greater for the older group, the younger group reported greater overall severity of somatic and psychological symptoms and psychosocial stressors than did the older group. In addition, the younger group reported a significantly greater number of physician visits and disability days. The unique contribution of age to the presence of psychological symptoms was examined with linear regression. A two-part model was constructed. At step 1, gender, race, education, and number of physical conditions explained 1.6% of the variance in the PHQ Psychological Symptom Severity Score (R 2.016, F(4, 2659) , p.0001). Age was added to the model at step 2. After controlling for gender, race, education, and number of physical conditions, age explained an additional 2.2% of the variance in the PHQ Psychological Symptom Severity Score (R 2.038, F(1, 2658) , p.0001). These results indicated that age was a significant and independent predictor of psychological symptoms. Further, the beta coefficient for age was negative, indicating an inverse relationship between age and reports of psychological symptoms. Prevalence rates were calculated for psychosocial stressors to determine the percentage of individuals in each group who reported being bothered a lot by each particular psychosocial stressor. As seen in Table 2, significant group differences exist for all stressors with the exception of little or no pleasure during sex. In each case, a significantly smaller percentage of individuals in the older group reported being bothered by that particular stressor than in the younger group. The most frequently endorsed stressor among the older individuals was worrying about your health, followed by your weight or how you look, something TABLE 2. Prevalence of Patient Health Questionnaire (PHQ) Specific Psychosocial Stressors, Older (n 534) vs. Younger (n 2466) patients PHQ Psychosocial Stressor Severe Stressor (%) a Older ( 65) Younger ( 65) Worrying about your health 10** 18 Your weight or how you look 9** 23 Something bad that happened recently 8** 13 Financial problems or worries 4** 19 The stress of taking care of children, parents, 4** 11 or other family members Little or no pleasure during sex 4 5 Difficulties with spouse 2** 8 Having no one to turn to when you have a 2** 8 problem Thinking or dreaming about something 2** 6 terrible that happened to you in the past Stress at work outside of the home or at school 1** 14 a Severe, only symptoms endorsed as bothering a lot. ** Significant difference from the younger group, p

4 J. C. KLAPOW et al. bad that happened recently, and financial problems or worries. Frequencies of each PHQ diagnostic category are presented in Table 3. For the younger group, the highest percentage (36%) of individuals was classified as symptom screen negative, followed closely by a large group of individuals (33%) who were categorized as symptom screen positive. Seventeen percent of the younger group were characterized as having threshold psychiatric diagnoses while 14% were categorized as having a subthreshold psychiatric diagnosis. The distribution of individuals falling into each of these categorizations was notably different in the older group. Although the largest percentage of individuals in the older group was also categorized as symptom screen negative, this percentage (59%) was much greater than that in the younger group (36%). Twenty-nine percent of the older group was categorized by the PHQ as symptom screen positive. Finally, the percentages of older individuals categorized as having subthreshold (7%) and threshold (5%) diagnoses were much smaller than those for the younger individuals. A more detailed analysis was conducted to determine the prevalence of each psychological disorder within the older and younger groups. Similar to the previous analysis, the older and younger groups differed significantly across all disorders. Prevalence rates for all disorders assessed by the PHQ were significantly higher in the younger group than in the older group (p.01 for all differences except that for TABLE 3. Prevalence of Patient Health Questionnaire (PHQ) Psychological Disorders in Older (n 534) vs. Younger (n 2446) Patients a Diagnostic Status Older ( 65) n (%) Younger ( 65) Symptom screen negative 315 (59) 854 (36) Symptom screen positive but no 156 (29) 791 (33) psychiatric diagnosis Subthreshold psychiatric diagnosis 36 (7) 329 (14) Threshold psychiatric diagnosis 27 (5) 408 (17) Psychological disorder Any mood disorder 41 (8) 419 (18) Major depressive disorder 8 (2) 127 (5) Other depressive disorder 33 (6) 292 (12) Any anxiety disorder 16 (3) 291 (12) Panic disorder 9 (2) 151 (6) Other anxiety disorder 9 (2) 204 (9) Probable alcohol abuse/dependence 16 (3) 183 (8) Any eating disorder 4 (1) 201 (8) Binge eating disorder 4 (1) 177 (7) Bulimia nervosa 0 (0) 24 (1) a All differences between older and younger groups are significant at p.01 (except bulimia nervosa, which is p.05). bulimia nervosa, p.05). The most common disorder in both the younger and older groups was other depressive disorder. To assess the relationship between psychological disorders and health outcomes, a detailed examination was conducted. Tables 4 and 5 examine the relationship between PHQ diagnostic category and perceived difficulty of problems, severity of somatic symptoms, disability days, and physician office visits. In both older and younger patients, after controlling for age and number of physical conditions, increasing severity of diagnostic status (eg, symptom screen negative, screen positive, subthreshold, threshold) was associated with increased perceived difficulty of problems. Likewise, the magnitude of mean somatic severity score increased significantly from the symptom screen-negative group to the threshold psychiatric diagnosis group. In regard to disability days, individuals in the threshold psychiatric diagnosis group reported the highest number of disability days. Severity of PHQ diagnostic status was not associated with the number of self-reported clinic visits in the past 3 months within the older group, but it was associated with clinic visits within the younger group. Tables 6 and 7 examine the relationship between PHQ diagnostic classification and health-related quality of life as assessed by each of the SF-20 subscales. For each of the six subscales, there was a general trend toward worsening health status as one progressed from the symptom screen-negative group to the threshold psychiatric diagnosis group. DISCUSSION In this study, older primary care patients reported fewer and less severe psychological symptoms than did younger patients. The average psychological symptom severity score for patients over the age of 65 was approximately half that of younger patients (see Table 1). We classified older patients as 65 years or greater for several reasons, including convention in geriatrics health services research, recommendations from special reports (28), and current Medicare definitions. However, when examined as a continuous variable in our regression model, increasing age showed a strong, independent, and inverse association with psychological symptom severity. While older patients had two to three times more chronic medical conditions than younger patients, the number of psychological disorders in the older group was significantly fewer. The prevalence rate of psychological disorders assessed by the PHQ was nearly three times higher for the younger cohort (17% vs. 5% in the older cohort). Mood and anxiety disorders were the 638

5 DISTRESS IN PRIMARY CARE PATIENTS TABLE 4. Relationship Between Patient Health Questionnaire (PHQ) Diagnostic Status and Severe Difficulty of Problems, Somatic Complaints, Disability Days, and Health Care Utilization in Older Subjects n Severe Difficulty of Problems a % Somatic Symptom Severity Mean (SD) b Disability Days in Past 3 Months Clinic Visits in Past 3 Months Symptom screen negative (4.0) A 2.3 (7.9) A 1.1 (1.7) Symptom screen negative but no (4.4) B 2.6 (9.1) A 1.5 (4.2) psychiatric diagnosis Subthreshold psychiatric diagnosis (5.2) B 3.4 (7.7) A 1.2 (1.4) Threshold psychiatric diagnosis (5.6) C 13.0 (25.5) B 2.2 (2.1) a Severe, responses of very difficult or extremely difficult to the following question: How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people? Chi-square 26.11; p.001. b Comparisons across somatic complaints, disability days, and clinic visits employed ANCOVA with age and number of physical conditions as covariates. Groups with different superscripts are significantly different from one another as determined by Tukey test with p.05. TABLE 5. Relationship Between Patient Health Questionnaire (PHQ) Diagnostic Status and Severe Difficulty of Problems, Somatic Complaints, Disability Days, and Health Care Utilization in Younger Subjects n Severe Difficulty of Problems a % Somatic Symptom Severity Mean (SD) b Disability Days in Past 3 Months Clinic Visits in Past 3 Months Symptom screen negative (3.8) A 2.1 (7.2) A 0.93 (1.8) A Symptom screen negative but no (4.4) B 4.8 (12.1) B 1.4 (2.2) B psychiatric diagnosis Subthreshold psychiatric diagnosis (4.6) C 6.8 (14.0) B 1.8 (3.1) C Threshold psychiatric diagnosis (4.8) D 17.3 (26.9) C 2.5 (3.8) D a Severe, responses of very difficult or extremely difficult to the following question: How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people? Chi-square 26.11; p.001. b Comparisons across somatic complaints, disability days, and clinic visits employed ANCOVA with age and number of physical conditions as covariates. Groups with different superscripts are significantly different from one another as determined by Tukey test with p.05. TABLE 6. Mean SF-20 Scale Scores Across Patient Health Questionnaire (PHQ) Diagnostic Categories in Older Subjects a SF-20 Scales Physical Social Role Mental Health Bodily Pain Health Perception Symptom screen negative 68.4 C,D 87.9 C,D 82.3 B,D 83.6 B,C,D 63.9 B,D 67.0 B,C,D Symptom screen positive but no 62.9 D 81.9 C,D 69.5 A 73.1 D 55.6 A,D 57.0 A,C,D psychiatric diagnosis Subthreshold psychiatric diagnosis 51.0 A 68.1 A,B A,D 58.0 D 44.1 A,B Threshold psychiatric diagnosis 43.1 A,B 53.6 A,B 52.1 A 53.7 A,B,C 36.7 A,B,C 31.9 A,B a Comparisons employed ANCOVA with age and number of physical conditions as covariates. Group differences indicated by superscripts were determined by Tukey test with p.05. most prevalent psychological disorders within both groups. The present study focused on characterizing a broad spectrum of psychological symptoms and disorders in older primary care patients. However, the prevalence rates of depression and depressive symptoms are consistent with previous studies in elderly populations. Specifically, relatively low levels of mood disorders are seen among older primary care patients relative to the general population, but a high incidence of depressive symptoms are present in the absence of a disorder (13, 23). Although the current study did not assess all psychological disorders, the findings also document lower rates of threshold and subthreshold anxiety, alcohol, and eating disorders among older primary care patients. Unique to the present study was the examination of both psychological symptoms and psychosocial stressors. Across all categories, older patients reported 639

6 J. C. KLAPOW et al. TABLE 7. Mean SF-20 Scale Scores Across Patient Health Questionnaire (PHQ) Diagnostic Categories in Younger Subjects a SF-20 Scales Physical Social Role Mental Health Bodily Pain Health Perception Symptom screen negative A 85.4 B,C,D 92.9 B,C,D 85.4 B,C,D 82.9 B,C,D 67.9 B,C,D 67.2 C,D Symptom screen positive but no 79.5 A,C,D 85.5 A,C,D 77.6 A,C,D 71.2 A,C,D 59.3 A,D 57.1 C,D psychiatric diagnosis B Subthreshold psychiatric diagnosis C 74.3 A,B,D 77.2 A,B,D 69.0 A,B,D 65.0 A,B,D 56.7 A,D 43.7 B Threshold psychiatric diagnosis D 58.5 A,B,C 55.8 A,B,C 40.2 A,B,C 41.3 A,B,C 44.1 A,B,C 29.9 A,B a Comparisons employed ANCOVA with age and number of physical conditions as covariates. Group differences indicated by superscripts were determined by Tukey test with p.05. fewer and less severe psychosocial stressors than younger patients. Health worries and concerns about something bad that had recently happened were the most commonly reported psychosocial stressors in the older sample. This finding is consistent with previous work suggesting that the death of a friend or family member, long-term care for a family member, or a major illness in self or spouse are the most common psychosocial stressors among older individuals (29, 30). Previous studies have documented the relationship between psychological symptoms and a broad range of outcomes in combined samples of older and younger patients (7, 10, 31). The present study examined this relationship in independent samples of older and younger primary care patients. Results indicated that, after controlling for age and number of physical conditions, severity of diagnostic status (eg, not ill, screen positive, subthreshold, threshold) in older patients was associated with reports of physical symptoms, health-related quality of life, disability days, and perceived difficulty of problems. It was not associated with reports of health care service use. A similar pattern of results was found in the younger group. The only difference in findings between the older and younger samples was a positive relationship between severity of PHQ diagnostic category and visits to a physician within the younger group. The lack of relationship between severity of psychiatric diagnostic status and use of health care services among older primary care patients has been documented previously in a study of over 1000 Medicare patients (14). Overall, these findings are consistent with previous validation studies of both the PHQ and its predecessor, the PRIME-MD (7, 10, 31). The current findings are intriguing and somewhat counterintuitive. As expected, older patients had a greater number of chronic medical conditions than younger patients. However, unlike some previous findings (32 35), this increased medical comorbidity was not associated with a greater number of psychological symptoms, disorders, or psychosocial stressors. In fact, older patients uniformly reported fewer psychological disorders and psychosocial stressors than did the younger cohort. Interpretation of these findings in the context of existing literature is difficult because previous studies of older patients have tended to focus on somatic symptoms and have lacked a comparison group of younger subjects (eg, 14, 36 38). There are several potential explanations for these findings. First, the elderly patients in this sample may truly have had fewer and less severe psychological symptoms and disorders than the younger cohort. While literature reviews have shown increased rates of some psychological disorders with certain comorbid medical conditions, eg, stroke, cancer, cardiac disease (32 35), the primary studies have often focused on single disorders being cared for in hospital or specialty clinic settings. Such patients probably have, on average, a greater severity of medical illness, which in turn substantially increases psychological comorbidity (32, 33, 35, 39). The chronic physical conditions cared for in primary care tend to be less serious and more stable. While one large population-based study found an increased prevalence of depression across a variety of chronic conditions (40), two clinic-based studies found psychological status was either not worse in patients with various chronic conditions compared with the general population (41) or significantly worse only for those patients with cancer (39). A second possible explanation for fewer psychological disorders in our older primary care patients may be that they underreport psychological symptoms to a greater degree than do younger patients. This reporting bias could occur for several reasons. First, older primary care patients may experience psychological distress with physical symptoms (eg, fatigue, difficulty sleeping) rather than emotional symptoms (23), thereby decreasing the rate of endorsement of psychological disorders. This explanation seems unlikely in 640

7 DISTRESS IN PRIMARY CARE PATIENTS the present study, however, because older patients, on average, also reported significantly lower somatic severity scores than younger patients. Second, older patients may tend to normalize symptoms of psychological distress more so than younger patients do, thus raising their threshold for symptom reports as well as for seeking care (36). Finally, the process of normalizing may be indicative of coping skills that are adequate to manage the experience of psychological symptoms without the need to seek health care services. Indeed, previous work has demonstrated a natural improvement in general coping skills with age (28). A third explanation for the present findings may be that the use of primary care services is less driven by symptom manifestation in older vs. younger patients. Greater medical comorbidity in the elderly may mean that more office visits are driven not by new symptoms (physical or psychological) but rather by scheduled follow-up of existing conditions for which symptoms are tolerable or, in some cases, absent when properly treated. Because younger patients have fewer chronic conditions that require ongoing management, a greater proportion of their office visits may be triggered by new symptoms. Fourth, it is possible that depressed patients die at a younger age, in which case they would be underrepresented in the older population. Because we considered a variety of psychological symptoms and disorders, however, our findings are not based solely on the prevalence of major depressive disorder. Moreover, our population of interest was older patients presenting for clinical care. Even if they constitute a survival cohort, they are in fact the older patients primary care clinicians will care for. Finally, demographic factors other than age may contribute to the current findings. The younger sample had 8% more women, who, compared with men, are known to have a higher prevalence of depressive and anxiety disorders (42 47). Although the younger sample also had a greater percentage of high-school graduates and fewer minority patients, the impact of education and ethnicity on the prevalence of psychological disorders is less established (7, 20, 48). Several possible limitations in our study should be noted. First, the cross-sectional nature of the study allowed only for a limited snap-shot of differences in presentation between older and younger patients. This precluded an examination of differences in the natural history of symptoms between the groups. Future prospective studies may begin to examine whether the prognosis (ie, natural history) of symptoms differs between age groups. Second, parameters of the study did not allow for data collection on individuals who refused to participate. While refusal rates were modest (approximately 30%), generalizability would be affected to the extent that older patients refused at a higher rate than younger patients or sicker patients refused at a higher rate than healthier patients. Third, the symptoms reported in the presented study were only those elicited by a standardized questionnaire. Through the use of semistructured interviews, future studies may also begin to determine whether older and younger patients differ in their presenting symptoms (chief complaints). The data collected on health care utilization was patient reported and focused on the frequency of visits. No information was collected on the reason for the visit. Therefore, it was not possible to determine whether visits were due to the occurrence of symptoms or for a scheduled follow-up. Future studies may begin to incorporate medical claims data to provide a more detailed description of health care utilization (type of visit, primary diagnosis, procedures, etc). Finally, while age was a significant and independent predictor of psychological distress after controlling for other factors such as gender, race, education, and comorbid conditions, it accounted for a small portion of the variance. It may be that other factors not examined in the current study are more powerful predictors of psychological distress. In summary, the present study documents a broad range of psychological symptoms and disorders in a large sample of older primary care patients. This is important because the primary care setting is the predominant source of behavioral health care for these patients. Prevalence rates of psychological symptoms and disorders differ in younger and older primary care patients and, somewhat contrary to clinical intuition, are lower among older primary care patients. It is important to emphasize, however, that the lower rates of disorders and distress are relative to younger patients. The findings in no way should be interpreted as evidence for discounting the possibility of psychological disorders among older primary care patients. Future studies can start to focus on possible explanatory factors, including differences in symptom perception among older and younger patients and age-related changes in health beliefs and coping skills. This study was supported in part by Grant AG from the National Institute on Aging. The development of PRIME-MD PHQ was underwritten by an educational grant from Pfizer US Pharmaceuticals Inc, New York, NY. PRIME-MD is a trademark of Pfizer Inc. Copyright 1999 Pfizer Inc. REFERENCES 1. Burnum JF. The worried sick. Ann Intern Med 1978;88: Kroenke K, Mangelsdorff AD. Common symptoms in ambulatory 641

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