NDT Advance Access originally published online on September 23, 2006
Nephrology Dialysis Transplantation 2007 22(1):203-208; doi:10.1093/ndt/gfl521
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Associations of race with depression and symptoms in patients on maintenance haemodialysis
1Renal Section, Medical Specialty Service Line, VA Pittsburgh Healthcare System, 2Center for Health Equity Research and Promotion, VA Pittsburgh Healthcare System and 3Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, 4Division of Renal Diseases and Hypertension, George Washington University School of Medicine, Washington, DC, 5Division of General Internal Medicine, Department of Medicine, University of Pittsburgh School of Medicine and 6Departments of Medicine and Psychiatry and the Center for Research on Health Care, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Correspondence and offprint requests to: Steven D. Weisbord, MD, MSc VA Pittsburgh Healthcare System, Mailstop 111F-U, 7E room 120 Pittsburgh, PA 15240, USA. Email: weisbordsd{at}upmc.edu
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Abstract |
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Background. Although studies have shown that African American haemodialysis patients report better overall quality of life than Whites, racial differences in depression and symptom burden remain less well characterized. The aim of this study was to compare these domains between African American and White patients on chronic haemodialysis.
Methods. We surveyed African American and White maintenance haemodialysis patients. Depression was assessed using the Beck Depression Inventory (BDI) and Cognitive Depression Index (CDI). Symptoms were evaluated using the Dialysis Symptom Index (DSI).
Results. Among the 82 Whites and 78 African Americans enrolled, there were no racial differences in the prevalence of depression (27% in African Americans vs 27% in Whites, P = 1.0), BDI Scores (11.2 vs 10.9, P = 0.6) or CDI scores (6.0 vs 6.0, P = 0.9). Symptom burden was substantial in both African Americans and Whites (median number of symptoms 8.5 and 9.0, respectively) with no racial differences in the overall burden or severity of symptoms. However, based on a single item, African Americans were more likely to describe their religious/spiritual beliefs as ‘very important’. Adjustment for demographic and treatment characteristics had no impact on the associations of race with depression or symptoms.
Conclusions. Depression and symptoms are highly prevalent in both African American and White haemodialysis patients, without racial differences in these health-related domains. In exploratory analyses, spiritual/religious beliefs appear to be of greater importance to African Americans. The relevance of these observations to the advantages in quality of life and survival among African Americans on haemodialysis warrants further investigation.
Keywords: depression; haemodialysis; spirituality; symptoms
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Introduction |
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Haemodialysis is a life sustaining treatment for patients with end-stage renal disease, yet is associated with substantial decrements in health-related quality of life (HRQoL) [1,2]. The rigours of a tri-weekly treatment schedule, metabolic derangements that are protean in patients with renal failure and the psychosocial and vocational impact of haemodialysis therapy are important mediators of the significantly impaired HRQoL of those dependent on this therapeutic modality [1,2]. Interestingly, a series of studies have demonstrated that African American haemodialysis patients report better overall HRQoL than their White counterparts [3]. The precise reasons for these racial differences remain incompletely elucidated, although potential explanations include socio-cultural and/or religious differences, variability in the adaptation to disease and disparate mechanisms for coping with chronic illness [4]. While differences in HRQoL between African American and White dialysis patients have been well described, racial differences in other aspects of the psychosocial and physical disease experience of this population have been less well characterized, including depression and symptom burden. Depression affects
20% of the patients on haemodialysis and has been linked to chronic pain, impaired HRQoL and an increased risk of mortality, while the burden of symptoms in this patient group mirrors that of patients with AIDS and several forms of cancer [5–7]. A small number of studies have examined the importance of spirituality among haemodialysis patients and suggest that spirituality impacts patients’ satisfaction with life and quality of life; however, these findings are based largely on studies done in predominantly African American populations [8]. Nonetheless, it remains largely unknown whether racial differences exist in these constructs as they do in overall HRQoL. In this study, we sought to compare the prevalence and severity of depression and symptoms between African American and White patients on maintenance haemodialysis. In addition, we sought to explore racial differences in the importance that patients attach to their spiritual and religious beliefs. |
Subjects and methods |
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We conducted a cross-sectional study in African American and White chronic haemodialysis patients. All patients receiving tri-weekly, in-centre haemodialysis for at least 3 months at one of the three dialysis units in Allegheny County, Pennsylvania were approached by dialysis unit personnel between January and April 2003. Patients who indicated a willingness to participate were subsequently approached by study personnel. No data were collected from patients who refused to participate. To help ensure that patients’ cognitive functioning was adequate to understand the details of the study and the informed consent procedure, a clock drawing task of executive function, the CLOX test, was administered. For every patient who passed the CLOX test and gave informed consent, a trained research assistant administered the study surveys verbally during a routine weekday dialysis session. We also collected clinical data from patients including history of diabetes mellitus, dialysis vintage and history of prior renal transplant as well as demographic data including self-reported race, age, gender, educational level, site of residence and marital status. As part of this demographic assessment, we also explored the importance that patients attached to spiritual/religious beliefs. Using a single item, patients were asked to rate the importance of religious/spiritual beliefs using a 4-point Likert scale ranging from ‘not at all important’ to ‘very important’.
Survey instruments
We used the Beck Depression Inventory (BDI) and its subscale, the Cognitive Depression Index (CDI) to assess the presence and degree of depression. The BDI is a 21-item, patient-rated scale that has been validated in the haemodialysis population [8,9]. Scores can range from 0 to 63, with higher scores indicating more severe depression. We defined the presence of depression as a categorical variable based on a BDI score of 15. This value was chosen because it has previously been shown to have high specificity and predictive value for a clinical diagnosis of major depressive disorder [10,11]. In patients with end-stage renal disease, the BDI correlates highly with diagnostic criteria of depression, quality of life, functional status, severity of illness and mortality over time [12]. From the BDI, we generated CDI scores, which are comprised of 15 BDI items, excluding the six items related to the somatic aspects of depression. The CDI, which targets patients’ thoughts and feelings about depression, has been correlated with the BDI and has been validated as a measure of depression in the haemodialysis population [13].
The Dialysis Symptom Index (DSI) was utilized to assess symptoms and their severity. The DSI is comprised of 30 items, each of which targets a specific physical or emotional symptom. Enrolled patients were asked to describe the presence (yes/no) of each symptom at any time during the previous 7 days. Using a 5-point Likert scale (1 = ‘not at all bothersome’ to 5 = ‘bothers very much’), the severity of each reported symptom was assessed by asking patients to rate the degree to which the symptom was bothersome. Two scores were generated from the DSI. First, an overall symptom burden score was formulated by totalling the number of symptoms reported as present. Second, a total symptom severity score was generated by summing the severity scores for each reported symptom, with a score of 0 for symptoms that were not reported as present. Using this scoring system, the minimum possible total severity score was 0 if none of the 30 symptoms was present and the maximum potential score was 150 if all the 30 symptoms were reported and rated as ‘bothers very much’ (severity score of 5).
Statistical analysis
For descriptive analyses, means and medians were used to describe continuous variables and, percentages and frequencies were used to describe categorical variables. Differences between African American and White patients in demographic variables including the importance attached to spiritual/religious beliefs, the prevalence of depression, BDI and CDI scores and overall symptom burden and severity were assessed using the chi-square test for categorical variables, two sample Student's t-test for normally distributed continuous variables and the Wilcoxon rank sum test for non-parametrically distributed continuous variables. Racial differences in the proportion of patients reporting individual symptoms on the DSI were assessed using the chi-square test employing the Bonferroni correction because of the multiple comparisons.
To examine potential mediators of the association of race with depression and symptoms, we explored individual two-way interactions of age, gender, diabetes mellitus, prior transplant, educational level and dialysis vintage with race. Linear regression models were employed for these analyses using the interaction terms as independent variables and overall symptom burden, total symptom severity and BDI and CDI scores as dependent variables. We also explored correlations among depression, symptoms and the importance that patients attached to spiritual/religious beliefs using Pearson's, and when appropriate, Spearman's correlation coefficient. A two sided P-value of <0.05 was considered statistically significant for all analyses that did not adjust for multiple comparisons. A P-value of <0.001 was employed in analyses that used a Bonferroni correction. STATA version 8.0 (College Station, TX) was used for all analyses.
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Results |
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Study population
Overall, 220 patients were approached for participation and 162 (73.6%) consented to participate and completed the study questionnaires; two Asian patients were excluded from the present analysis. Of the 160 study patients, 139 (87%) were from Dialysis Clinic Incorporated units and 21 (13%) were from a Veterans Affairs dialysis unit. The 78 African American participants were younger than their 82 White counterparts and were more likely to have diabetes (Table 1).
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Race and depression
The mean BDI score for the entire study population was 11.0 ± 7.8. There were no differences in mean BDI scores between African Americans and Whites (11.2 vs 10.9, P = 0.6). The proportion of African American patients with depression (BDI score
15) was not different from the proportion of Whites with this condition (27 vs 27%, P = 1.0). Comparable proportions of African Americans and Whites reported scores on the BDI of greater than 18 (13 vs 15%, P = 0.7), which correlates with moderate to severe depression. The mean overall CDI score was 6.0 ± 5.7, and CDI scores did not differ by race (6.0 in African Americans and 6.0 in Whites, P = 0.9). None of the interaction terms of demographic/clinical variables with race had statistically significant associations with either BDI or CDI scores.
Race and symptoms
The median number of symptoms in the overall patient population was 9.0 (IQR 6–13) and was similar among African Americans and Whites (8.5 and 9.0, respectively, P = 0.7). The most commonly reported symptoms in African Americans were dry skin, bone or joint pain, dry mouth and feeling tired/lack of energy; each of which was described by >50% of the patients. Among Whites, the most common symptoms were feeling tired/lack of energy, dry skin, itching, trouble falling asleep and trouble staying asleep. African Americans reported trouble staying asleep less frequently than Whites, while cough and decreased appetite were more commonly described among African Americans, although differences were of borderline statistical significance (Table 2).
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Overall symptom severity scores were nearly identical in both racial groups (median severity score 25 in African Americans and 24 in Whites, P = 0.9). Decreased interest in sex was reported as being more severe by African Americans than by Whites (mean severity 2.4 vs 1.8, P = 0.05), although this difference failed to meet statistical significance with Bonferroni correction. Notably, there were no gender differences in this symptom among either African Americans or Whites. Difficulty becoming sexually aroused was reported as more severe among African Americans, (3.1 vs 1.9, P = 0.001). Men were more likely to report this symptom than women, and this gender difference was greater among African Americans (47 vs 14%, P = 0.001) than among Whites (41 vs 24%, P = 0.12). There was a trend for African Americans to report more severe irritability (2.0 vs 1.4, P = 0.07), and less severe dry skin (1.6 vs 1.9, P = 0.1) and headache (1.8 vs 2.3, P = 0.1) (Table 3). Although the interaction between race and diabetes mellitus had a borderline statistically significant relationship with overall symptom prevalence (P = 0.08), none of the other two-way interaction terms were associated with either overall symptom burden or total symptom severity.
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Race and the importance of spiritual/religious beliefs
Although our assessment of the importance attached to spiritual and religious beliefs was exploratory, we uncovered interesting findings in this domain. Overall, 63% of the patients rated their religious/spiritual beliefs as ‘very important’, while only 6% described their religious/spiritual beliefs as ‘not at all important’. However, African Americans were more likely to report religious/spiritual beliefs as ‘very important’ than Whites (74 vs 52%, P = 0.004), while a smaller proportion of African Americans reported their religious/spiritual beliefs as ‘not at all important’ (3 vs 10%, P = 0.06) (Figure 1).
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Correlations of depression, symptoms and the importance of spiritual/religious beliefs
In the overall population, symptom burden, symptom severity, and BDI and CDI scores were highly correlated. Because of the observed racial differences in the importance that patients attached to spiritual/religious beliefs, we explored associations of depression and symptoms with this domain, yet found no statistically significant correlations. In linear regression models, the interaction of race with the importance of spiritual/religious beliefs on BDI and CDI scores had an effect approaching statistical significance (P = 0.1). When stratified by race, the correlations of the importance of spiritual/religious beliefs with BDI scores, and to a larger extent CDI scores, were significantly stronger among African Americans than Whites (Table 4).
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Discussion |
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In this cross-sectional survey study, depression and symptoms were common and frequently reported as severe in both African Americans and Whites. We found no racial differences in the overall prevalence or severity of depression or symptoms. Preliminary and exploratory analyses suggest that African Americans attach greater importance to their spiritual/religious beliefs than Whites. Despite the high overall prevalence and severity of depression, we found no racial differences in this health-related domain; findings that are novel, yet not entirely unexpected. In an analysis of HRQoL among more than 1700 HEMO study patients, Unruh et al. [1] found no differences in the Mental Health Component Summary Score of the Kidney Disease Quality of Life Long Form between African Americans and Whites, suggesting that psychological well-being is comparable in these racial groups. Conversely, Watnick and colleagues [10] used the BDI to assess depression in a cohort of incident dialysis patients and found higher rates of depression among Whites than African Americans. It is important to note that Watnick et al. [10] examined depression in patients newly initiated on dialysis, whereas our findings reflect depression among prevalent haemodialysis patients. The impact of dialysis vintage on the development of depression, particularly among African Americans, is worthy of further investigation.
We also uncovered no racial differences in overall symptom burden or symptom severity. There also appear to be few racial differences in the prevalence or severity of individual symptoms. Although prior studies of the association of race with symptoms have yielded conflicting results, they all suggest that symptoms are common [14,15]. As a part of the HRQoL assessment conducted by Unruh et al. [1] among HEMO study patients, scores on the Kidney Disease Quality of Life Long Form suggested the presence of fewer symptoms among African Americans than Whites [16]. Although the observed difference in symptoms was statistically significant, the absolute magnitude of the difference was relatively small. Kutner and colleagues examined symptoms in 183 African American and 125 White older haemodialysis patients using ad hoc questions administered in the context of personal interviews [17]. African Americans were less likely to report nausea, sexual dysfunction and fatigue than Whites. Interestingly, we found no racial differences in the prevalence of symptoms related to sexual dysfunction, yet these symptoms were described as more severe by African Americans. Differences in survey techniques and patient populations may underlie these conflicting observations. More recently, Kimmel and colleagues [18] explored symptoms in a cohort of 165 haemodialysis patients. There were no racial differences in the proportion of patients reporting one or more symptoms or who described the presence of pain, which was the most commonly reported symptom in this study. While we also found no racial differences in the description of pain, this was one of the most commonly described symptoms in both African Americans and Whites in our study population, underscoring the potential importance of this symptom to this group of patients.
Our findings have implications for clinical care and future research. First, a significant proportion of African Americans and Whites had BDI scores consistent with a diagnosis of depression, while an average of more than eight symptoms were reported by study patients. These observations underscore the importance for providers to assess both African American and White patients for the presence of depression and bothersome symptoms. Studies in the general population have shown that anti-depressant use is considerably more common among Whites [19]. Among depressed patients initiating dialysis, only 16% have been found to be receiving treatment [10]. Our findings should prompt investigation of whether there is under-treatment of depression among prevalent dialysis patients and if racial disparities exist in the treatment of depression in the dialysis population. Second, it appears unlikely that differences in depression or symptoms account for previously observed racial differences in HRQoL. As a part of this study, we did assess quality of life with the Illness Effects Questionnaire (data not shown). Our African American patients tended to have a lower burden of illness (better HRQoL), suggesting that our study patients were representative of the broader dialysis population. Future efforts to examine reasons for the racial variation in HRQoL in the haemodialysis population should consider alternative explanations for this unusual phenomenon.
In exploratory analyses, we found that spiritual/religious beliefs may be of greater importance to African Americans than Whites. Prior studies have demonstrated a similar phenomenon and correlated spirituality with depressive affect and quality of life [8]. While we did not find statistically significant correlations between the importance that patients attached to spiritual/religious beliefs and depression or symptoms, more robust inverse associations between this domain and depression were seen among African Americans. This is consistent with data showing that African Americans are more likely than Whites to use religion to cope with illness [20]. While the relationship between spiritual and religious beliefs and healthcare outcomes is controversial, this intriguing finding in our study might help to explain, at least in part, the outcome advantages that African Americans have on dialysis. Further research on the impact of spirituality and religiosity on outcomes, particularly as it relates to the yet unexplained survival advantage of African Americans on chronic dialysis therapy, should be conducted using validated instruments to assess spiritual and religious beliefs and practices.
This study has several limitations. First, our study sample was relatively small, leading to limited power to discern subtle differences in study outcomes. However, any observed differences in BDI, CDI and symptom scores were small and unlikely to have clinical significance. Second, we used a single ad hoc item to measure the importance of spiritual/religious beliefs. Although appearing to have a significant face validity, this single item question had not been previously validated. Therefore, our findings on the importance of spiritual/religious beliefs should be viewed as preliminary and hypothesis-generating. Third, over 25% of the patients who were initially approached regarding this study refused to participate, which could have biased our results. Lastly, we did not assess patients’ comorbid illness burden, treatment-related parameters such as haemoglobin level, nutritional status, or adequacy of dialysis, or treatment for depression or psychiatric disease. However, there is little reason to believe that meaningful racial differences in these metrics existed in our study patients.
In summary, this study suggests that the proportion of African American and White haemodialysis patients who suffer from depression and bothersome symptoms is high, yet comparable. There may be small differences between African Americans and Whites in the prevalence and severity of individual symptoms, although firm conclusions on the clinical significance of such differences cannot be established from this study. The use of psychometrically sound instruments for the assessment of depression and symptoms in the present study supports the validity of our findings. There may be potential racial differences in the importance that patients attach to spiritual/religious beliefs; a finding that warrants further investigation. Future studies are needed to confirm our observations and to examine the impact that depression, symptom burden and spiritual/religious beliefs have on long-term outcomes including survival among African American and White haemodialysis patients.
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Acknowledgements |
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Dr Weisbord was supported by a VA Health Services Research and Development Career Development Award (RCD 03-176) and a pilot grant from the VA Center for Health Equity Research and Promotion. Dr Fine was supported in part by a mid-career development award (K24 AI001769) from the National Institute of Allergy and Infectious Diseases.
Conflict of interest statement. None declared.
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References |
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Accepted in revised form: 7. 8.06
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