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The Impact of Chronic Pain on Depression, Sleep, and the Desire to Withdraw from Dialysis in Hemodialysis Patients

      Abstract

      Pain is a multidimensional phenomenon with physical, psychological, and social components and is a significant problem for 50% of hemodialysis (HD) patients. Failure to treat pain adequately may lead to disruption in many aspects of life. This study examines the relationship between moderate to severe chronic pain and depression, insomnia, and the desire to withdraw from dialysis in HD patients. In a cross-sectional study of 205 Canadian HD patients, patients completed a questionnaire that included the Brief Pain Inventory, Beck Depression Inventory, and the Pittsburgh Sleep Quality Index. One hundred and three patients (50.2%) reported chronic pain and 85 (41.4%), moderate to severe pain. There was a higher prevalence of depression in patients with moderate or severe chronic pain compared to patients with mild or no pain (34.1% vs. 18.3%, odds ratio [OR]=2.31, P=0.01). Severe irritability, anxiousness, and inability to cope with stress were all more common in patients with pain compared to patients without pain (P<0.001). There was a higher prevalence of insomnia in patients with moderate or severe chronic pain compared to patients with mild or no pain (74.7% vs. 53.0%, OR=2.32, P=0.02). Although consideration of withdrawal from dialysis was significantly associated with moderate or severe pain compared to no or mild pain (46% vs. 16.7%, P<0.001), death due to withdrawal from dialysis was not. Chronic pain in HD patients is associated with depression and insomnia and may predispose patients to consider withdrawal of dialysis.

      Key Words

      Introduction

      End-stage renal disease (ESRD) is a major public health problem. Given the aging population and the increasing incidence of diabetes and hypertension, the prevalence of ESRD is projected to nearly double in the next decade.
      • Xue J.L.
      • Ma J.Z.
      • Louis T.A.
      • Collins A.J.
      Forecast of the number of patients with end-stage renal disease in the United States to the year 2010.
      During recent decades, dialysis has proven to be a successful life-sustaining therapy, with its effectiveness judged largely by patient survival. However, as the population ages and experiences multiple comorbidities, it appears increasingly difficult to maintain reasonable health-related quality of life (HRQOL).
      Pain, depression, and insomnia are highly relevant patient outcomes in evaluating HRQOL. Chronic pain is a significant problem for 50% of hemodialysis (HD) patients and pain management is suboptimal, with 55% of these patients rating their pain as severe.
      • Davison S.N.
      Pain in hemodialysis patients: prevalence, cause, severity, and management.
      However, pain is a multidimensional phenomenon with physical, psychological, and social components. Failure to treat pain adequately could be expected to lead to disruption in many aspects of life, such as functional status, mood, and sleep. Recent research suggests that patient perceptions of physical symptoms, especially pain, may be more important than objective assessments in determining the HRQOL of patients with ESRD.
      • Kimmel P.L.
      • Emont S.L.
      • Newmann J.M.
      • Danko H.
      • Moss A.H.
      ESRD patient quality of life: symptoms, spiritual beliefs, psychosocial factors, and ethnicity.
      In addition, it is well recognized in the literature that depression and insomnia adversely affect HRQOL and are common problems for people with chronic pain. Despite this, the impact of pain in patients with ESRD in relation to major contributors to HRQOL, such as depression and insomnia, has not been well studied.
      The purpose of this study was to determine the relationship between chronic pain and depression, insomnia, and the desire to withdraw from dialysis in HD patients. We hypothesized that moderate to severe chronic pain would be independently associated with a greater prevalence of depression and insomnia in HD patients and would predispose patients to consider withdrawal of dialysis.

      Methods

      Patient Selection

      This was a cross-sectional study of 205 HD patients attending four HD units (two in-center and two satellite HD units) at the University of Alberta, Canada. The study was conducted between September, 2001 and July, 2002. All eligible patients were invited to participate. Eligibility criteria included the following: age older than 18 years, on HD for ≥3 months, and the ability to converse and complete the questionnaires in English. Ethics approval was obtained from the University of Alberta Health Research Ethics Board, and written informed consent was obtained from all participants.

      Assessments and Instruments

      A chart review was conducted to collect demographic and clinical data, including cause of ESRD, biochemical indices, comorbidity, and investigations for and etiology of pain. Participants were evaluated using a detailed pain history questionnaire that asked patients if they had a problem with chronic pain. Patients completed the questionnaires while they were on HD during a midweek treatment. Chronic pain was defined as pain of greater than 3 months' duration. Pain severity was assessed using the Brief Pain Inventory-Short Form (BPI). The impact of chronic pain was measured using the BPI and a collection of tools that are described below.
      The BPI
      • Daut R.L.
      • Cleeland E.S.
      • Flanery R.C.
      Development of the Wisconsin Brief Pain Questionnaire to assess pain in cancer and other diseases.
      is a widely used, self-administered tool that includes four pain intensity items and seven pain interference items. Patients rate their current pain, as well as their average, least, and worst pain, in the prior 24 hours, on scales of 0–10, with 0 being no pain and 10 being severe pain. The seven interference items reflect dimensions of daily life: ability to walk, usual activity, work, mood, relationships with others, sleep, and enjoyment in life. Patients are asked how, during the past 24 hours, pain has interfered with these dimensions of daily life, each of which is rated on a scale of 0–10, with 0 reflecting no interference and 10 reflecting complete interference. Pain severity and interference items are rated as mild if scored 0–4, moderate if scored 5–6, and severe if scored 7–10.
      Depression was measured using the Beck Depression Inventory II (BDI).
      • Beck A.T.
      • Steer R.A.
      • Brown G.K.
      BDI-II manual.
      This is a 21-item self-report scale measuring characteristic attitudes and symptoms of depression. It uses 0–3 Likert scales, with total scores ranging from 0 to 63. Although the gold standard for the psychiatric diagnosis of Major Depression is the interview using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria, the BDI is a well-validated measure of depression in patients with ESRD,
      • Craven J.L.
      • Rodin G.M.
      • Littlefield C.
      The Beck Depression Inventory as a screening device for major depression in renal dialysis patients.
      as well as in patients with chronic pain.
      • Turner J.A.
      • Romano J.M.
      Self-report screening measures for depression in chronic pain patients.
      • Geisser M.E.
      • Roth R.S.
      • Robinson M.E.
      Assessing depression among persons with chronic pain using the Center for Epidemiological Studies-Depression Scale and the Beck Depression Inventory: a comparative analysis.
      It has been shown that a BDI score of ≥19 has high diagnostic sensitivity and specificity for depression and correlates with diagnostic criteria.
      • Beck A.T.
      • Steer R.A.
      • Brown G.K.
      BDI-II manual.
      • Craven J.L.
      • Rodin G.M.
      • Littlefield C.
      The Beck Depression Inventory as a screening device for major depression in renal dialysis patients.
      Typically, the somatic aspects of depression are included in diagnostic evaluations and scoring systems for depression. However, symptoms of medical illness can make the diagnosis of depression more difficult in patients with a chronic medical illness. For this reason, the Cognitive Depression Index (CDI) was developed. It is a 15-item subscale of the BDI in which somatic items of the BDI have been deleted and the total score ranges from 0 to 45. This also has been used in patients with ESRD.
      • Kimmel P.L.
      Psychosocial factors in adult end-stage renal disease patients treated with hemodialysis: correlates and outcomes.
      The CDI and BDI scores are both presented.
      Insomnia was measured with the Pittsburgh Sleep Quality Index (PSQI).
      • Buysse D.J.
      • Reynolds III, C.F.
      • Monk T.H.
      • Berman S.R.
      • Kupfer D.J.
      The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research.
      It is a self-report questionnaire that assesses seven aspects of sleep: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Scoring for each component is on a Likert scale of 0–3. The sum of scores for these seven components yields a global score between 0 and 21. A score of >6 is an indicator of clinically relevant sleep disturbance and results in a sensitivity for insomnia of 93.4% and a specificity of 100%.
      • Backhaus J.
      • Junghanns K.
      • Broocks A.
      • Riemann D.
      • Hohagen F.
      Test-retest reliability and validity of the Pittsburgh Sleep Quality Index in primary insomnia.
      It has been used for the assessment of insomnia in ESRD and chronic pain.
      • Sayar K.
      • Arikan M.
      • Yontem T.
      Sleep quality in chronic pain patients.
      • Iliescu E.A.
      • Coo H.
      • McMurray M.H.
      • et al.
      Quality of sleep and health-related quality of life in haemodialysis patients.
      Questions regarding anxiety and ability to cope with stressful situations were asked using Likert scales of 0–5. Participants were also asked about whether they had considered withdrawal of dialysis, and six potential reasons for this were explored. These were generated from the literature surrounding withdrawal of life-sustaining treatment. The questionnaire was self-administered and completed at home and returned to an experienced research assistant at the next dialysis treatment who then reviewed the questionnaire for completeness.

      Statistical Analysis

      Statistical analyses were performed using SPSS 11.5 (SSPS, Inc., Chicago, IL). Results are expressed as mean±SD for continuous variables and percentages for categorical variables. Descriptive statistics were calculated for global and composite scores for each assessment tool. To assess the relationship between pain severity and the various study variables, patients were grouped in terms of their pain severity based on the Serlin et al. classification, where no or mild pain corresponds to a “worst pain” rating of 0–4, moderate pain corresponds to a “worst pain” rating of 5–6, and severe pain corresponds to a “worst pain” rating of 7–10.
      • Serlin R.C.
      • Mendoza T.R.
      • Nakamura Y.
      • Eduards K.R.
      • Cleeland C.S.
      When is cancer pain mild, moderate or severe? Grading pain severity by its interference with function.
      Mild pain has a limited impact on functional status so patients with mild or no pain were compared to patients with moderate to severe pain.
      • Cleeland C.S.
      • Nakamura Y.
      • Mendoza T.R.
      • et al.
      Dimensions of the impact of cancer pain in a four country sample: new information from multidimensional scaling.
      Mean scores were treated as continuous variables and compared by using t-tests. Percentages for categorical variables were compared using the Chi-squared test. We individually examined the effect of patient characteristics on binary outcomes (no-mild pain/moderate-severe pain, insomnia, depression, and consideration of or death from withdrawal of dialysis) using univariate logistic regression analysis. We then determined which characteristics were independently associated with these outcomes using multivariate logistic regression analyses including independent variables that were significantly associated with the outcome (P<0.2) in univariate analyses. Factors considered included age, gender, marital status, time on dialysis, comorbidity, and PSQI and BDI scores. The multivariate models were examined by means of a purposeful regression with independent variables entered or removed based on the significance of the Wald test statistic. Potentially important variables removed were assessed for confounding through observed changes in the regression coefficients (β) or odds ratios (ORs) of the variables retained in the final model. A variable was considered to be an important confounder and retained in the final model if it changed at least one β coefficient or OR by >15%. P<0.05 is considered statistically significant.

      Results

      There were 251 eligible patients, of whom 205 (81.7%) consented to participate. The 46 patients who refused participation stated that they did not wish to complete the questionnaire; of these, 18 (39%) were taking analgesics. Characteristics of participating patients are shown in Table 1. One hundred and three of the 205 participating patients reported a problem with chronic pain (50.2%), and 85 (41.4%) reported moderate to severe chronic pain. Musculoskeletal pain was most common (61.3%) and was equal in severity to ischemic and neuropathic pain, which accounted for 9.7% and 12.6% of pain, respectively. Data on the prevalence, etiology, severity, and management of the pain have been described fully elsewhere.
      • Davison S.N.
      Pain in hemodialysis patients: prevalence, cause, severity, and management.
      Table 1Characteristics of Patients with No-Mild Pain Compared to Patients with Moderate-Severe Pain
      No-Mild Pain, n=120 (%)Moderate-Severe Pain, n=85 (%)PAll, n=205 (%)
      Age in years
       <5029 (24.2)29 (34.1)58 (28.3)
       50–6957 (47.5)26 (30.6)83 (40.5)
       70+34 (28.3)30 (35.3)64 (31.2)
       Mean±SD60.9±15.858.8±16.10.3760.0±15.9
      Gender0.07
       Female44 (36.7)32 (49.4)86 (42.0)
       Male76 (63.3)43 (50.6)119 (58.0)
      Marital status0.34
       Never married14 (11.7)16 (18.8)30 (14.6)
       Married72 (60.0)46 (54.1)118 (57.6)
       Widowed17 (14.2)8 (9.4)25 (12.2)
       Separated/divorced17 (14.2)15 (17.6)32 (15.6)
      Ethnic origin0.17
       Caucasian90 (75.6)70 (82.4)160 (78.4)
       Asian14 (11.8)2 (2.4)16 (7.8)
       First Nations7 (5.9)6 (7.1)13 (6.4)
       African2 (1.7)1 (1.2)3 (1.5)
       Other6 (5.0)6 (7.1)12 (5.9)
      Etiology of ESRD0.06
       Diabetes38 (31.2)23 (27.1)61 (31.2)
       Polycystic kidney disease (PCKD)8 (6.7)9 (10.6)17 (8.3)
       Glomerulonephritis24 (20.0)16 (18.8)40 (19.5)
       Hypertension20 (16.7)11 (12.9)31 (15.1)
       Other25 (20.8)19 (22.4)44 (21.5)
       Unknown5 (4.2)7 (8.2)12 (5.9)
      Comorbidity
       Hypertension74 (61.7)44 (51.8)0.16118 (57.6)
       Diabetes mellitus50 (41.6)26 (30.6)0.0176 (37.1)
       Ischemic heart disease32 (26.7)28 (32.9)0.3360 (29.3)
       Cerebrovascular disease15 (12.5)7 (8.2)0.3322 (10.7)
       Peripheral vascular disease6 (5.0)9 (10.6)0.1315 (7.3)
       Malignancy8 (6.7)7 (8.2)0.6715 (7.3)
      Time on HD (months)
      Categorized based on approximate tertiles.
      <0.01
       ≤947 (39.2)17 (20.5)64 (31.5)
       9–2438 (31.7)28 (33.7)66 (32.5)
       >2435 (29.2)38 (45.8)73 (36.0)
       Mean±SD27.0±39.842.1±59.8<0.0133.2±49.4
       Median13.919.515.6
      Insomnia
       PSQI, mean±SD7.2±7.311.8±7.4<0.0113.8±3.2
       Yes (PSQI>6)62 (53.0)59 (74.7)<0.01121 (61.7)
      Depression
       BDI, mean±SD13.1±6.321.9±8.416.7±7.2
       CDI, mean±SD6.4±4.48.9±5.97.4±4.9
       Yes (BDI19)22 (18.3)29 (34.1)<0.0151 (24.9)
      Consideration of withdrawal of HD
       Yes20 (16.7)39 (45.9)<0.0159 (28.8)
      Death due to withdrawal of HD
       Yes7 (5.8)7 (8.2)0.5014 (6.8)
      a Categorized based on approximate tertiles.
      Compared to patients with mild or no pain, patients with moderate or severe chronic pain had been on dialysis for longer (42.1 vs. 27.0 months, P=0.04) (Table 1). BDI and CDI scores were significantly higher in patients with moderate to severe pain compared to those patients with no or mild pain, indicating a greater burden of depressive symptoms. Thirty-four percent of patients with moderate to severe pain had a BDI19, meeting the criterion for moderate depression, compared to 18.3% of patients with no or mild pain (P<0.01). The prevalence of insomnia was significantly higher in HD patients with moderate to severe pain compared to HD patients with mild or no pain (74.7% vs. 53.0%, P<0.01). Even among those patients with insomnia, the PSQI scores were significantly higher in patients with moderate-severe pain than in patients with no-mild pain (11.8±7.4 vs. 7.2±7.3, P<0.01), indicating a more severe degree of sleep dysfunction. This was primarily a function of worse subjective sleep quality and daytime dysfunction. Consideration of withdrawal of HD was almost three times as likely in patients with chronic pain as in patients with no or mild chronic pain (45.9% vs. 16.7%, P<0.01), although the pain itself was not identified as the most common reason for considering withdrawal of dialysis in those patients (Table 2). As of April 30, 2004, 56 (27.3%) of the 205 patients had died. Of these deaths, 14 (25.0%) were a result of withdrawal from dialysis. Eight of the 14 patients (57%) had considered withdrawal at the time of the study and 6 (43%) had not. Although consideration of withdrawal of HD was significantly associated with moderate or severe chronic pain, death due to withdrawal of HD was not. All other patient characteristics were similar between the two groups.
      Table 2Reasons for Consideration of Withdrawal of Dialysis
      No-Mild Pain
      Pain severity was defined using worst pain scores on the BPI.
      (n=120)
      Moderate-Severe Pain
      Pain severity was defined using worst pain scores on the BPI.
      (n=85)
      P
      Number of patients (%)20 (16.7)39 (45.9)<0.001
      Reasons for consideration of withdrawal from dialysis
      Totals add to more than 100% as more than one reason could be given.
       Pain (%)3 (15.0)19 (48.7)0.012
       Loss of satisfaction with life (%)17 (85.0)28 (71.8)NS (0.34)
      Not statistically significant (P > 0.05).
       Loneliness (%)5 (25.0)11 (28.2)NS (0.99)
      Not statistically significant (P > 0.05).
       Sense of burden on others (%)10 (50.0)18 (46.2)NS (0.59)
      Not statistically significant (P > 0.05).
       Loss of control (%)10 (50.0)22 (56.4)NS (0.78)
      Not statistically significant (P > 0.05).
       Other (%)2 (10.0)6 (15.4)NS (0.79)
      Not statistically significant (P > 0.05).
      a Pain severity was defined using worst pain scores on the BPI.
      b Totals add to more than 100% as more than one reason could be given.
      c Not statistically significant (P > 0.05).
      Chronic pain in this population of HD patients was often severe. The BPI severity items showed that 82.5% of patients with chronic pain experienced moderate or severe pain in the previous 24 hours (Table 3). Pain was also associated with significant interference in all aspects of life as defined by the BPI interference items. Fifty-five percent of patients with chronic pain felt that their pain resulted in a moderate to severe interference with their mood, and 62% felt that their pain resulted in a moderate to severe interference with sleep. A greater percentage of patients with moderate to severe pain had significant irritability, anxiety, or difficulty coping with stressful situations than patients with no or mild pain (P<0.001, data not shown). There was significantly greater dissatisfaction with sleep, use of medications, daily activities, recreational activities, relationships, physical functioning, emotional functioning (P<0.01), and sexual functioning (P=0.04) in patients with moderate-severe pain compared to those with no or mild pain (data not shown).
      Table 3Brief Pain Inventory Scores (n=103)
      Mild (0–4)
      Pain severity and interference items are assessed with a 0–10 Likert scale: mild is defined as 0–4, moderate is defined as 5–6, and severe is defined as 7–10.
      Moderate (5–6)Severe (7–10)Mean BPI Score (SD)
      Pain severity items
       Worst18 (17.5%)28 (27.2%)57 (55.3%)7.03 (2.40)
       Least77 (74.8%)17 (16.5%)9 (8.7%)3.07 (2.82)
       Average43 (41.7%)31 (30.1%)29 (28.2%)5.61 (2.21)
       Now46 (44.7%)29 (28.2%)28 (27.2%)4.99 (2.96)
      Interference items
       Activity33 (32.0%)20 (19.4%)50 (48.5%)6.16 (3.18)
       Mood46 (44.7%)34 (33.0%)28 (22.3%)4.42 (2.4)
       Walk37 (35.9%)50 (48.5%)18 (17.5%)4.08 (3.6)
       Work34 (33.0%)13 (12.6%)56 (54.4%)6.35 (3.57)
       Relationships48 (46.6%)16 (15.5%)39 (37.9%)4.82 (3.81)
       Sleep39 (37.9%)24 (23.3%)40 (38.8%)5.17 (3.58)
       Enjoyment27 (26.2%)22 (21.4%)54 (52.4%)6.68 (3.20)
      a Pain severity and interference items are assessed with a 0–10 Likert scale: mild is defined as 0–4, moderate is defined as 5–6, and severe is defined as 7–10.
      Univariate and multivariate analyses to determine predictors of both depression and insomnia can be seen in Tables 4 and 5, respectively. Although insomnia predicted depression with borderline significance (P=0.09) in the univariate analysis, pain was the only independent and significant (P=0.01) predictor of depression in the final multivariate model. Pain and younger age were independent predictors of insomnia. There was also a significant association between consideration of withdrawal of HD and insomnia. Interactions between pain, insomnia, depression, consideration of withdrawal from dialysis, time on dialysis, age, and gender were tested for, but all were nonsignificant (P>0.1).
      Table 4Odds Ratios and 95% Confidence Intervals for Depression
      UnivariateMultivariate
      OR (95% CI)POR (95% CI)P
      Age in years
       <501.0
       50–690.58 (0.26–1.26)0.17
       70+0.94 (0.43–2.07)0.89
      Gender
       Male1.0
       Female1.32 (0.70–2.49)0.39
      Time on HD (months)
       ≤91.0
       9–240.61 (0.27–1.42)0.25
       >241.12 (0.53–2.37)0.77
      Pain
      Moderate or severe pain as defined using “worst” pain on the BPI.
      2.31 (1.21–4.39)0.012.31 (1.21–4.39)0.01
      Insomnia1.86 (0.91–3.82)0.09
      Death due to withdrawal1.75 (0.56–5.49)0.34
      Withdrawal consideration1.84 (0.94–3.58)0.07
      OR=odds ratios; 95% CI=95% confidence intervals.
      Marital status, ethnic origin, etiology of ESRD, and comorbidity were not significant by univariate and/or multivariate analysis and are not shown.
      a Moderate or severe pain as defined using “worst” pain on the BPI.
      Table 5Odds Ratios and 95% Confidence Intervals for Insomnia
      UnivariateMultivariate
      OR (95% CI)POR (95% CI)P
      Age in years
       <501.01.0
       50–690.41 (0.18–0.91)0.030.47 (0.20–1.09)0.08
       70+0.21 (0.09–0.47)<0.010.19 (0.08–0.45)<0.01
      Gender
       Male1.0
       Female1.00 (0.56–1.79)0.99
      Time on HD (months)
       ≤91.0
       9–241.29 (0.63–2.64)0.49
       >241.73 (0.85–3.54)0.13
      Pain
      Moderate or severe pain as defined using “worst” pain on the BPI.
      2.62 (1.40–4.88)<0.012.32 (1.16–4.65)0.02
      Depression1.86 (0.91–3.82)0.09
      Death due to withdrawal2.40 (0.65–8.90)0.19
      Withdrawal consideration3.44 (1.65–7.21)<0.012.96 (1.34–6.55)<0.01
      OR=odds ratios; 95% CI=95% confidence intervals.
      Marital status, ethnic origin, etiology of ESRD, and comorbidity were not significant by univariate and/or multivariate analysis and are not shown.
      a Moderate or severe pain as defined using “worst” pain on the BPI.

      Discussion

      Chronic pain is a common problem for HD patients, is often severe, and is suboptimally treated.
      • Davison S.N.
      Pain in hemodialysis patients: prevalence, cause, severity, and management.
      The causes are numerous and often multifactorial for any given patient, making the diagnosis a challenge.
      • Davison S.N.
      Pain in hemodialysis patients: prevalence, cause, severity, and management.
      This study shows that chronic pain is significantly associated with depression and insomnia. There was also evidence that pain may be associated with considerations of withdrawal from dialysis, although this was not associated with death from withdrawal of dialysis.

      Depression

      In this study, moderate to severe chronic pain was associated with depression, anxiety, irritability, and greater difficulty coping with stressful situations. Depression is a common and often underdiagnosed problem in patients with ESRD, with a prevalence of 20%–50% depending on the tool used to measure depression.
      • Smith M.D.
      • Hong B.A.
      • Robson A.M.
      Diagnosis of depression in patients with end-stage renal disease. Comparative analysis.
      Self-reported depression by two simple questions as well as depression scores using the BDI are associated with increased risks of mortality and hospitalization for HD patients, as well as decreased HRQOL.
      • Lopes A.A.
      • Bragg J.
      • Young E.
      • et al.
      Depression as a predictor of mortality and hospitalization among hemodialysis patients in the United States and Europe.
      • Kimmel P.L.
      • Peterson R.A.
      • Weihs K.L.
      • et al.
      Multiple measurements of depression predict mortality in a longitudinal study of chronic hemodialysis outpatients.
      The high prevalence of depression is likely, in part, due to the multiple and radical lifestyle changes required of dialysis patients. However, the role of chronic pain in depression of ESRD patients is not as readily acknowledged. The results of this study are consistent with those of another smaller study in HD patients that reported a positive association between pain severity and self-reported depression and anxiety.
      • Alvarez-Ude F.
      • Fernandez-Reyes M.J.
      • Vazquez A.
      • Mon C.
      • Sanchez R.
      Physical symptoms and emotional disorders in patient on a periodic hemodialysis program.
      All potential confounders for depression, such as time on dialysis, age, gender, insomnia, and comorbidity, were not predictive of depression. These results are also consistent with the general population, where chronic pain and depression frequently coexist. In the National Health and Nutrition Epidemiologic Follow-Up Study, depressive symptoms were found to be the variable most closely linked to chronic musculoskeletal pain.
      • Magni G.
      • Rossi M.R.
      • Rigatti-Luchini S.
      • Merskey H.
      Chronic abdominal pain and depression. Epidemiologic findings in the United States. Hispanic Health and Nutrition Examination Survey.
      Pain itself may be the cause of depressive symptoms by imposing limits on activities that are intrinsically rewarding or by altering perceptions of control over one's life. The reporting of pain as a symptom of depression, or as an expression of “masked depression,” has also been considered, although this remains controversial.
      • Scharff L.
      • Turk D.C.
      Chronic pain and depression in the elderly.
      However, the ways in which chronic pain patients cope or adjust to their illness are likely central to understanding the great variability across patients in their ability to function with their pain. This concept is well stated in the term “total pain,” first used by Cicely Saunders, who emphasized the contribution of psychological, spiritual, and social factors to the experience of pain. Regardless of the exact nature of this relationship, the implication of these findings is that health care providers will need to pay more attention to diagnosing and treating depression in HD patients if they are to provide adequate pain management. Conversely, attention to adequate pain assessment and management will likely have a significant positive impact on depressive symptomatology of HD patients.

      Insomnia

      In this study, moderate to severe chronic pain was independently associated with insomnia. It is estimated that 4%–29% of the general population experiences sleep disturbances (trouble falling asleep and/or nighttime waking). However, the prevalence increases in patients with a chronic illness such as ESRD. The overall prevalence of insomnia was 61.7% in this study, comparable to the 45%–86% prevalence reported in other studies of dialysis patients.
      • Sabbatini M.
      • Minale B.
      • Crispo A.
      • et al.
      Insomnia in maintenance haemodialysis patients.
      However, insomnia is also a significant problem in patients with chronic pain. It has been estimated that between 50% and 88% of patients with chronic nonmalignant pain have significant sleep disturbances.
      • Morin C.M.
      • Gibson D.
      • Wade J.
      Self-reported sleep and mood disturbance in chronic pain patients.
      However, insomnia is a defining symptom of major depression using DSM-IV criteria. It is not clear whether the relationship between pain and insomnia is due to comorbidity with depression or whether insomnia has independent or even additive effects when they occur together. In this study, pain was significantly associated with insomnia, but depression was significant neither in univariate analysis nor in multivariate analysis. Depression was neither a confounder nor an effect modifier. Poor sleep in HD dialysis patients has been associated with multiple factors, such as time on dialysis, dialysis shift, high levels of parathyroid hormone, age, gender, history of ischemic heart disease, high phosphate levels, anemia, and poorer mental and physical HRQOL.
      • Unruh M.L.
      • Hartunian M.G.
      • Chapman M.M.
      • Jaber B.L.
      Sleep quality and clinical correlates in patients on maintenance dialysis.
      Although the relationship between chronic pain and insomnia is poorly understood, studies of other patient populations have found that the sleep disturbance is correlated with higher pain intensity, greater levels of depression and anxiety, and reduced activity levels. It has been suggested that sleep disturbance in chronic pain patients may increase pain sensitivity, increase attention to pain, interfere with daily functioning, and create a self-perpetuating cycle of sleep disruption, increased pain, and depression. Although pain and younger age were significantly associated with insomnia in this study, increased time on dialysis and depression were not.

      Withdrawal from HD

      Patients were more likely to have considered or be considering withdrawal of dialysis if they suffered from chronic pain. A loss of satisfaction with life, sense of burden on others, and a loss of control were the most common reasons for considering withdrawal from dialysis in all patients, regardless of pain. However, this did not translate into more deaths as a result of withdrawals from dialysis due to pain. This may in part be due to the small numbers. Little is known about end-of-life decision making for dialysis patients. We do know that most decisions to withdraw from dialysis are associated with a prior decrease in HRQOL and that approximately 50% of patients experience significant pain at the time of withdrawal from dialysis.
      • Cohen L.M.
      • Germain M.
      • Poppel D.M.
      • Woods A.
      • Kjellstrand C.M.
      Dialysis discontinuation and palliative care.
      If patients are withdrawing from dialysis due to pain, such a finding would be contrary to extensive studies in other populations of terminally ill patients, where decisions to hasten death are not usually related to pain but more to depression, hopelessness, loss of control, and fears of being a burden to others.
      This study has several limitations. It was confined to four dialysis units in Western Canada, and the results may not be generalizable to other HD populations. Although well-validated tools were used to assess depression and insomnia, the questions asked to assess considerations of withdrawal of dialysis were not part of a validated tool. Recurrent disease-specific complaints, such as muscle cramps and pruritis, were not specifically studied and, therefore, these results likely underrepresent the burden of painful symptoms experienced by HD patients. In addition, a causal relationship between chronic pain, and depression and insomnia cannot be established by this study. This study did not attempt to examine all important determinants of HRQOL, including spiritual beliefs and perception of social support. The relationship between chronic pain and these determinants of HRQOL needs to be studied to fully understand the impact of chronic pain within a comprehensive assessment of HRQOL.

      Summary

      This study suggests that chronic pain in HD patients is significantly associated with depression and insomnia. If we are to provide comprehensive care and improve HD patients' HRQOL, we need to pay more attention to our patients' chronic pain. Depression and insomnia appear to be integral parts of the experience of chronic pain for HD patients and should be carefully evaluated in all HD patients with chronic pain.

      Acknowledgments

      The authors thank Judy Peng for help with the administration of pain questionnaires.

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