Article
Depression: An important factor associated with disability among patients with chronic low back pain
The International Journal of Psychiatry in Medicine 2015, Vol. 49(3) 187–198 ß The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0091217415573937 ijp.sagepub.com
Ching-I Hung1, Chia-Yih Liu1, and Tsai-Sheng Fu2
Abstract Objective: The study aimed to compare the associations of pain indices, depression, anxiety, and somatic symptoms with disability among outpatients with chronic low back pain (CLBP). Method: Consecutive orthopedics outpatients with CLBP in a medical center were enrolled. The Oswestry Disability Index and physical functioning and role limitationsphysical of the Short-Form 36 were used as disability indices. The Hospital Anxiety and Depression Scale (HADS) and the Depression and Somatic Symptoms Scale were employed. Pain intensity was rated using a visual analogue scale. Multiple linear regressions were used to determine the impacts of these independent factors related to disability. Results: Among 225 participants (122 male, 103 female) with CLBP, patients with major depressive disorder and associated leg symptoms of CLBP had higher disability indices. A tendency was noted that depression (HADS-depression) had the highest correlation to the three disability indices, followed by pain intensity, anxiety, and somatic symptoms. After controlling for demographic variables, HADS-depression explained the highest variance of disability, followed by pain intensity. Conclusion: Depression was the most powerful factor associated with disability of CLBP among depression, anxiety, and somatic symptoms. Depression should be evaluated when investigating disability among patients with CLBP.
1 Department of Psychiatry, Chang Gung Memorial Hospital at Linko and Chang Gung University College of Medicine, Taoyuan, Taiwan 2 Department of Orthopedics, Chang Gung Memorial Hospital at Keelung and Chang Gung University College of Medicine, Taoyuan, Taiwan
Corresponding author: Tsai-Sheng Fu, Department of Orthopedics, Chang Gung Memorial Hospital at Keelung, 7F, No.222, Maijin Road, Keelung, 20401, Taiwan. Email: [email protected]
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The International Journal of Psychiatry in Medicine 49(3)
Keywords Anxiety, depression, disability, low back pain, somatization
Introduction Chronic low back pain (CLBP) and affective disorders are closely correlated and interact.1–8 CLBP is a common painful physical symptom among patients with major depressive disorder (MDD).9 Patients with CLBP also have a high prevalence of depression.10 Moreover, psychological stress has negative impacts on patients with CLBP.2,3 Psychological factors (notably distress, depressive mood, and somatization) are implicated in the transition to CLBP.6,7,11 CLBP is related to disability in multiple dimensions. Pain intensity and frequency as well as psychological stress are common factors related to disability of CLBP.1,5,12–14 Depression, anxiety, anger, catastrophizing response, and somatization also have been reported to be important factors related to disability.1,5,12,15–18 Although there are many studies related to the impacts of psychological factors on disability among patients with CLBP, some studies reported controversial results.1,16,19 For example, Moix et al.1 reported that the association of trait anxiety with disability is greater than that of depression; Hall et al.16 demonstrated that the symptoms of depression and stress, but not anxiety, are responsible for mediation of the pain–disability relationship; and Ledoux et al.19 found that none of the psychological questionnaires could explain the variations observed in functional capacity in elderly patients with CLBP, after adjusting for physical activity and disability levels. Moreover, studies simultaneously comparing the associations of pain indices, depression, anxiety, somatic symptoms, and other factors with disability of CLBP are rare. Clarifying this issue is important because gaining an understanding of the ranking of these factors might allow physicians to address the most important factors during treatment for CLBP and disability. Therefore, the purpose of this study was to rank the associations of pain indices, depression, anxiety, somatic symptoms, and other factors with disability among patients with CLBP. We hypothesized that psychological factors might be as important as pain indices in terms of disability among patients with CLBP.
Methods Sample and procedures This study, approved by the institutional review board of the Chang Gung Memorial Hospital, was conducted in the general orthopedics clinic of the same hospital from August 2008 to November 2010. The inclusion criteria were (1) consecutive orthopedics outpatients who first visited our orthopedics clinic and were 20–65 years of age; and (2) patients with low back pain for at least three months. To prevent
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disability and health-related quality of life (HRQoL) from being confounded, the following exclusion criteria were established: (1) patients who had taken antidepressants or antipsychotics within the past four weeks; and (2) psychotic symptoms, mental retardation, or severe cognitive impairment with obvious difficulty being interviewed. Written informed consent, based on the guidelines regulated in the Declaration of Helsinki, was obtained from all subjects prior to study enrollment. After enrollment, physical examinations were performed and the findings of plain radiographs were diagnosed by a board-certified orthopedist. Then, these participants were interviewed by a board-certified psychiatrist who was blind to the data related to CLBP. MDD was diagnosed based on the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision, Axis I Disorders.20
Assessment of disability related to CLBP The Oswestry Disability Index (ODI), including 10 items, is one of the most commonly used functional outcomes for evaluating how back or leg pain is affecting the patient’s ability to manage in everyday life.21,22 It has been extensively tested and shows good psychometric properties. Each of the 10 items is scored from 0 to 5, and the maximum score is 50. The obtained score can be multiplied by 2 to produce a percentage score. A percentage score 40 was considered to indicate severe disability or crippling. The Short-Form 36 (SF-36) is a self-administered 36-item questionnaire that measures HRQoL in eight domains: physical functioning (PF), role limitationsphysical (RP), bodily pain, general health perceptions, vitality, social functioning, role limitations-emotional (RE), and mental health.23 The Taiwanese version of the SF-36 shows good validity and reliability.24 In addition to the ODI, the PF and RP of the SF-36—acute version, which evaluates HRQoL in the past week, were also used as disability indices. The PF evaluates how health limits physical activities, such as self-care, walking, climbing stairs, bending, lifting, and moderate and vigorous exercise. The RP evaluates how physical health interferes with work or other daily activities, including limitations in the kind of activities performed or difficulty in performing activities. Therefore, the two subscales also represented physical disability. In calculating the SF-36 scores, the responses to items within each domain are summed and linearly transformed to produce domain scores ranging from 0 (lowest well-being) to 100 (highest well-being). A higher ODI score and lower scores of the PF and RE represented greater disability.
Assessment of the severity of pain, depression, anxiety, and somatic symptoms Average pain intensity in the past week was rated by visual analogue scale and pain frequency (pain days in the past week) was also recorded. Histories and
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associated data related to CLBP were collected, such as past operational history for CLBP, exercise habit, obesity, and smoking cigarettes. Two scales—the Hospital Anxiety and Depression Scale (HADS) and the Depression and Somatic Symptoms Scale (DSSS)—were used to evaluate the severity of depression, anxiety, and somatic symptoms.25,26 The HADS, without any somatic symptom items, evaluates depression (HADS-D) and anxiety (HADS-A) severity simultaneously. The DSSS evaluates depression and somatic severity simultaneously, including 12 items on the depression subscale (DS) and 10 items on the somatic subscale (SS), which was composed of five pain and five non-pain somatic symptoms. The reliability and validity of the DSSS have been proved.27,28 The DSSS was significantly correlated with the Hamilton Depression Rating scale and the HADS in the patients with depression.25,27,28 In a preliminary study among patients with CLBP, the DSSS was also significantly (p < 0.001) correlated with the HADS (correlation coefficient ¼ 0.74 and 0.53 for the DS and HADS-D and SS and HADS-A, respectively; moreover, the Cronbach’s alpha values were 0.90 and 0.83 for the DS and the SS, respectively (unpublished data). The total scores range from 0 to 21 for the HADS-D and HADS-A, 0 to 36 for the DS, and 0 to 30 for the SS. A higher score indicates a higher severity of symptoms.
Statistical methods All statistical analyses were performed using SPSS for Windows 12.0 (SPSS Inc., Chicago, IL, USA). The independent t test, Pearson’s correlation, and the Chisquare test were used in appropriate situations. Multiple linear regression with backward selection was used to determine the rankings of the associations between the factors that were independently associated with the three disability indices. The dependent variables were the scores of the three disability indices. The independent variables included five demographic variables (age, gender, educational years, marital status, and employment), pain intensity, pain frequency, HADS-A, HADS-D, DS, SS, associated leg symptoms, MDD, abnormal radiographic findings, previous operational history, exercise habit, smoking cigarettes, obesity, and medical comorbidities. In all statistical analyses, a twotailed test with a p value
Depression: An important factor associated with disability among patients with chronic low back pain
The International Journal of Psychiatry in Medicine 2015, Vol. 49(3) 187–198 ß The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0091217415573937 ijp.sagepub.com
Ching-I Hung1, Chia-Yih Liu1, and Tsai-Sheng Fu2
Abstract Objective: The study aimed to compare the associations of pain indices, depression, anxiety, and somatic symptoms with disability among outpatients with chronic low back pain (CLBP). Method: Consecutive orthopedics outpatients with CLBP in a medical center were enrolled. The Oswestry Disability Index and physical functioning and role limitationsphysical of the Short-Form 36 were used as disability indices. The Hospital Anxiety and Depression Scale (HADS) and the Depression and Somatic Symptoms Scale were employed. Pain intensity was rated using a visual analogue scale. Multiple linear regressions were used to determine the impacts of these independent factors related to disability. Results: Among 225 participants (122 male, 103 female) with CLBP, patients with major depressive disorder and associated leg symptoms of CLBP had higher disability indices. A tendency was noted that depression (HADS-depression) had the highest correlation to the three disability indices, followed by pain intensity, anxiety, and somatic symptoms. After controlling for demographic variables, HADS-depression explained the highest variance of disability, followed by pain intensity. Conclusion: Depression was the most powerful factor associated with disability of CLBP among depression, anxiety, and somatic symptoms. Depression should be evaluated when investigating disability among patients with CLBP.
1 Department of Psychiatry, Chang Gung Memorial Hospital at Linko and Chang Gung University College of Medicine, Taoyuan, Taiwan 2 Department of Orthopedics, Chang Gung Memorial Hospital at Keelung and Chang Gung University College of Medicine, Taoyuan, Taiwan
Corresponding author: Tsai-Sheng Fu, Department of Orthopedics, Chang Gung Memorial Hospital at Keelung, 7F, No.222, Maijin Road, Keelung, 20401, Taiwan. Email: [email protected]
188
The International Journal of Psychiatry in Medicine 49(3)
Keywords Anxiety, depression, disability, low back pain, somatization
Introduction Chronic low back pain (CLBP) and affective disorders are closely correlated and interact.1–8 CLBP is a common painful physical symptom among patients with major depressive disorder (MDD).9 Patients with CLBP also have a high prevalence of depression.10 Moreover, psychological stress has negative impacts on patients with CLBP.2,3 Psychological factors (notably distress, depressive mood, and somatization) are implicated in the transition to CLBP.6,7,11 CLBP is related to disability in multiple dimensions. Pain intensity and frequency as well as psychological stress are common factors related to disability of CLBP.1,5,12–14 Depression, anxiety, anger, catastrophizing response, and somatization also have been reported to be important factors related to disability.1,5,12,15–18 Although there are many studies related to the impacts of psychological factors on disability among patients with CLBP, some studies reported controversial results.1,16,19 For example, Moix et al.1 reported that the association of trait anxiety with disability is greater than that of depression; Hall et al.16 demonstrated that the symptoms of depression and stress, but not anxiety, are responsible for mediation of the pain–disability relationship; and Ledoux et al.19 found that none of the psychological questionnaires could explain the variations observed in functional capacity in elderly patients with CLBP, after adjusting for physical activity and disability levels. Moreover, studies simultaneously comparing the associations of pain indices, depression, anxiety, somatic symptoms, and other factors with disability of CLBP are rare. Clarifying this issue is important because gaining an understanding of the ranking of these factors might allow physicians to address the most important factors during treatment for CLBP and disability. Therefore, the purpose of this study was to rank the associations of pain indices, depression, anxiety, somatic symptoms, and other factors with disability among patients with CLBP. We hypothesized that psychological factors might be as important as pain indices in terms of disability among patients with CLBP.
Methods Sample and procedures This study, approved by the institutional review board of the Chang Gung Memorial Hospital, was conducted in the general orthopedics clinic of the same hospital from August 2008 to November 2010. The inclusion criteria were (1) consecutive orthopedics outpatients who first visited our orthopedics clinic and were 20–65 years of age; and (2) patients with low back pain for at least three months. To prevent
Hung et al.
189
disability and health-related quality of life (HRQoL) from being confounded, the following exclusion criteria were established: (1) patients who had taken antidepressants or antipsychotics within the past four weeks; and (2) psychotic symptoms, mental retardation, or severe cognitive impairment with obvious difficulty being interviewed. Written informed consent, based on the guidelines regulated in the Declaration of Helsinki, was obtained from all subjects prior to study enrollment. After enrollment, physical examinations were performed and the findings of plain radiographs were diagnosed by a board-certified orthopedist. Then, these participants were interviewed by a board-certified psychiatrist who was blind to the data related to CLBP. MDD was diagnosed based on the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision, Axis I Disorders.20
Assessment of disability related to CLBP The Oswestry Disability Index (ODI), including 10 items, is one of the most commonly used functional outcomes for evaluating how back or leg pain is affecting the patient’s ability to manage in everyday life.21,22 It has been extensively tested and shows good psychometric properties. Each of the 10 items is scored from 0 to 5, and the maximum score is 50. The obtained score can be multiplied by 2 to produce a percentage score. A percentage score 40 was considered to indicate severe disability or crippling. The Short-Form 36 (SF-36) is a self-administered 36-item questionnaire that measures HRQoL in eight domains: physical functioning (PF), role limitationsphysical (RP), bodily pain, general health perceptions, vitality, social functioning, role limitations-emotional (RE), and mental health.23 The Taiwanese version of the SF-36 shows good validity and reliability.24 In addition to the ODI, the PF and RP of the SF-36—acute version, which evaluates HRQoL in the past week, were also used as disability indices. The PF evaluates how health limits physical activities, such as self-care, walking, climbing stairs, bending, lifting, and moderate and vigorous exercise. The RP evaluates how physical health interferes with work or other daily activities, including limitations in the kind of activities performed or difficulty in performing activities. Therefore, the two subscales also represented physical disability. In calculating the SF-36 scores, the responses to items within each domain are summed and linearly transformed to produce domain scores ranging from 0 (lowest well-being) to 100 (highest well-being). A higher ODI score and lower scores of the PF and RE represented greater disability.
Assessment of the severity of pain, depression, anxiety, and somatic symptoms Average pain intensity in the past week was rated by visual analogue scale and pain frequency (pain days in the past week) was also recorded. Histories and
190
The International Journal of Psychiatry in Medicine 49(3)
associated data related to CLBP were collected, such as past operational history for CLBP, exercise habit, obesity, and smoking cigarettes. Two scales—the Hospital Anxiety and Depression Scale (HADS) and the Depression and Somatic Symptoms Scale (DSSS)—were used to evaluate the severity of depression, anxiety, and somatic symptoms.25,26 The HADS, without any somatic symptom items, evaluates depression (HADS-D) and anxiety (HADS-A) severity simultaneously. The DSSS evaluates depression and somatic severity simultaneously, including 12 items on the depression subscale (DS) and 10 items on the somatic subscale (SS), which was composed of five pain and five non-pain somatic symptoms. The reliability and validity of the DSSS have been proved.27,28 The DSSS was significantly correlated with the Hamilton Depression Rating scale and the HADS in the patients with depression.25,27,28 In a preliminary study among patients with CLBP, the DSSS was also significantly (p < 0.001) correlated with the HADS (correlation coefficient ¼ 0.74 and 0.53 for the DS and HADS-D and SS and HADS-A, respectively; moreover, the Cronbach’s alpha values were 0.90 and 0.83 for the DS and the SS, respectively (unpublished data). The total scores range from 0 to 21 for the HADS-D and HADS-A, 0 to 36 for the DS, and 0 to 30 for the SS. A higher score indicates a higher severity of symptoms.
Statistical methods All statistical analyses were performed using SPSS for Windows 12.0 (SPSS Inc., Chicago, IL, USA). The independent t test, Pearson’s correlation, and the Chisquare test were used in appropriate situations. Multiple linear regression with backward selection was used to determine the rankings of the associations between the factors that were independently associated with the three disability indices. The dependent variables were the scores of the three disability indices. The independent variables included five demographic variables (age, gender, educational years, marital status, and employment), pain intensity, pain frequency, HADS-A, HADS-D, DS, SS, associated leg symptoms, MDD, abnormal radiographic findings, previous operational history, exercise habit, smoking cigarettes, obesity, and medical comorbidities. In all statistical analyses, a twotailed test with a p value
