Prevalence of depressive symptoms in Japanese male patients with chronic obstructive pulmonary disease

Authors


Hideaki Senjyu, PhD, Department of Health Sciences, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8520, Japan. Email: senjyu@nagasaki-u.ac.jp

Abstract

Aim:  The objective of this study was to utilize commonly applied tools, the Hospital Anxiety and Depression Scale – Depression subscale (HADS-D) and the Center for Epidemiological Studies Depression Scale (CES-D), to screen for depressive symptoms in patients with stable chronic obstructive pulmonary disease (COPD). Furthermore, we sought to identify whether differences existed in the prevalence of depressive symptoms as assessed by CES-D and HADS-D, and predictors of depressive symptoms.

Methods:  The presence of depressive symptoms in 80 outpatients and 51 inpatients with stable COPD was assessed using the CES-D and HADS-D. Data regarding sex, educational level, body mass index, smoking index and pulmonary function were obtained to evaluate their independent contribution as predictors of depressive symptoms.

Results:  The prevalence of depressive symptoms was 29.8% based on CES-D and 40.5% based on HADS-D. A MacNemar test of COPD severity and analysis of the results of depressive symptoms based on CES-D and HADS-D revealed significant differences. Logistic regression analysis suggested that ‘severity’ is a predictor of depressive symptoms as assessed by CES-D, whereas ‘body mass index’, ‘education level’ and ‘setting’ were predictors of depressive symptoms as assessed by HADS-D.

Conclusions:  The prevalence of depressive symptoms differed when assessed with CES-D and HADS-D. The reasons behind this difference include the fact that HADS-D frequently detected depressive symptoms in patients with mild COPD as well as a tendency for HADS-D to be strongly influenced by education levels. In contrast, the severity of COPD was reflected in CES-D. It is possible that prevalence of depressive symptoms differs in accordance with the applied screening tool.

THE WORLD HEALTH Organization estimates that the prevalence of chronic obstructive pulmonary disease (COPD) will rise rapidly and that COPD will be the third leading cause of death in the world by 2020.1 As a result, in recent years, numerous studies pertaining to rehabilitation and other therapies for persons with COPD have been conducted.2 Furthermore, considerable interest exists with respect to depressive symptoms as a common finding in patients with COPD.3–5 In individuals with COPD, depressive symptoms are associated with impaired quality of life (QOL)6 and with adverse effects on disease progression and mortality.7 These factors lead to an increase in health care utilization and the concomitant economic burden attributable to COPD.8,9 Symptoms of depression in patients with COPD are amenable to treatment in a manner similar to the physical symptoms associated with COPD; thus, treatment of depressive symptoms is considered important.10–12

Many previous investigations have reported the prevalence of depressive symptoms in COPD. Although these symptoms are recognized more often in patients with COPD than in patients presenting with other chronic diseases,3 the actual prevalence in reported studies, which varies considerably, ranges from approximately 20% to 80%.13 Van Ede et al. highlighted a scarcity of research relating to the diversity and adequacy of screening tools used for assessing depressive symptoms as well as the poor quality of the research methodology, including small subject numbers.14 A number of screening tools have been utilized for the assessment of depressive symptoms; moreover, it is possible that this non-uniformity is responsible for the wide range in the reported prevalence of depressive symptoms in COPD.

Therefore, the objective of this study was to utilize commonly applied tools, the Hospital Anxiety and Depression Scale – Depression subscale (HADS-D) and the Center for Epidemiological Studies Depression Scale (CES-D),13 to screen for depressive symptoms in a large cohort of patients with stable COPD. Furthermore, we sought to determine whether differences exist in the prevalence of depressive symptoms as assessed by CES-D and HADS-D, and what factors are predictors of depressive symptoms.

METHODS

Subjects

Subjects comprised of 131 men with a medical diagnosis of COPD who were hospitalized or had attended the outpatient department of one of seven hospitals, or one clinic in Japan between November 2007 and December 2008. All subjects lived in one of two cities within one prefecture. At the time of the study, 51 subjects had been admitted to the hospital for ongoing management of their condition (average age, 73.3 years, range, 55–93) and 80 were outpatients/home-care patients (average age, 72.4 years, range, 55–89). The study was approved by the Ethics Committee of Nagasaki University and all subjects provided written informed consent prior to participation in the study. Subjects were required to be in a stable condition with no recent acute exacerbation. Exclusion criteria consisted of unstable medical conditions and any factor preventing completion of the scales, e.g. impaired cognitive function, including dementia.

Measurement of depressive symptoms

Subjects completed the CES-D and HADS-D in a single session. The order of completion of the scales was randomized.

The CES-D is a self-administered rating scale developed by the United States National Institute of Mental Health for the purpose of investigating the prevalence of depressive symptoms in the general population.15 The highest possible total score is 60; a score of 16 points or higher suggests the presence of clinical depressive symptoms; however, this score does not allow a diagnosis of depression to be made. Consistent with previous studies, cases were divided into two groups: subjects demonstrating a score of 15 points or less were classified as ‘not having depressive symptoms’ and those exhibiting a score of 16 points or higher were classified as ‘having depressive symptoms’.

The HADS is a rating scale that assesses anxiety and depression in patients with physical disorders.16 The HADS is comprised of 14 items, seven of which assess depressive symptoms and seven of which assess anxiety. Consistent with the CES-D, the HADS does not allow a definitive diagnosis of depression to be made. In this study, only data pertaining to the items regarding depressive symptoms were scored (expressed as ‘HADS-D’). For the HADS-D, a total score of 0–7 points represents ‘no depressive symptoms’, 8–10 points represents ‘suspect diagnosis’ and 11–21 points represents ‘certain diagnosis of depressive symptoms’. In this investigation, in order to compare HADS-D results with assessment results based on CES-D, total scores were classified into two categories (scores of 7 points or lower were considered as ‘having no depressive symptoms’ and scores of 8 points or higher were considered as ‘having depressive symptoms’) so as to minimize false negative cases in accordance with previous research.

This study utilized Japanese versions of the CES-D and the HADS.17,18

Other measures

The following data were also collected: gender, age, setting (inpatients or outpatients), body composition (body mass index [BMI]), marital status, smoking index (pack years) and education level. Individuals with a score of 0–40 pack years were considered ‘light smokers’ and those with a score of 41 and higher were considered ‘heavy smokers’. In terms of education level, patients were classified into two groups: ordinary higher elementary and junior high school graduates were considered as having ‘low education’; and high school, junior college or university graduates were considered as having ‘high education’. Spirometry was measured in all subjects; subsequently, the data were used to classify subjects into one of four categories (‘mild case’, ‘moderate case’, ‘severe case’ and ‘very severe case’) in accordance with the GOLD severity classification.2

Statistical analysis

The prevalence of depressive symptoms in COPD patients was determined by calculating the percentage of subjects exhibiting a score of 16 points or higher for CES-D and 8 points or higher for HADS-D among the total number of subjects. McNemar's test was used to determine whether there was a significant difference in the frequency of depressive symptoms based on each scale. To evaluate the consistency in the assessment of depressive symptoms assessed utilizing the two scales, correlation analysis involving the total scores for each scale was performed using Pearson's correlation coefficients. In addition, to clarify the characteristics of each scale, the correlations between depressive symptoms, and sex, setting, marital status, education level and smoking index were compared using the χ2-test. The correlations between COPD severity and the existence of depressive symptoms was also examined using the Cochran-Armitage test.

Logistic regression analysis was implemented to determine predictors of depressive symptoms as determined with HADS and CES-D. Independent variables examined were age, BMI, marital status, education level, smoking index, setting and COPD severity. The adjusted odds ratios (OR) and 95% confidence intervals (95%CI) were calculated. All analyses were performed using spss Version 16.0 (IBM Japan, Tokyo, Japan). Significance was accepted when P < 0.05.

RESULTS

Clinical characteristics and prevalence of depression

The clinical characteristics of all subjects are shown in Table 1. The mean scores for CES-D and HADS-D were 13.4 ± 8.0 and 6.9 ± 4.1, respectively. The percentage of patients who were judged as having depressive symptoms based on the scores of each scale was 29.8% (n = 39) for CES-D and 40.5% (n = 53) for HADS-D; these data were indicative of a significantly higher number of patients exhibiting depressive symptoms as based on HADS-D (P < 0.01).

Table 1.  Clinical characteristics of the 131 subjects
VariablesMeanSDRange
  1. BMI, body mass index; CES-D, Center for Epidemiological Studies Depression Scale; COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in one second; FEV1/FVC, percent of forced expiratory volume in one second; FEV1predicted, forced expiratory volume in one second as a percentage of the predicted value; HADS-D, subscale of the Hospital Anxiety and Depression Scale; VC, vital capacity; %VC, percent of vital capacity.

Sex   
 Male131  
Setting inpatients/ outpatients51/80  
Severity of COPD mild/ moderate/severe/very severe15/46/42/28  
Age (years)72.78.155–93
Height (cm)1626146.0–185
Weight (kg)551136.4–87.6
BMI (kg/m2)20.93.514.8–30.5
VC (L)3.60.71.3–4.8
%VC (%)103.41947.4–144.0
FEV1 (L)1.20.50.5–1.2
FEV1%predicted (%)51.12011.9–93.9
FEV1/FVC (%)40.21816.9–71.0
CES-D (score)13.480–42
HADS (score)6.94.10–18

Correlations between subject characteristics and depressive symptoms

A moderate correlation was evident between the scores obtained using CES-D and HADS-D (Fig. 1). The correlations between subject characteristics and evidence of depressive symptoms are presented in Table 2. With HADS-D, depressive symptoms were detected significantly more frequently in inpatients and in patients with low education levels (Table 2). Figure 2 displays the prevalence of depressive symptoms with respect to COPD severity for CES-D and HADS-D, respectively. With both scales, there was a trend towards greater depressive symptoms and increasing severity of COPD (CES-D, P = 0.001; HADS-D, P = 0.032). In contrast however, a greater number of subjects with mild COPD were classified as ‘having depressive symptoms’ based on HADS relative to CES-D.

Figure 1.

Correlation between Center for Epidemiological Studies Depression Scale (CES-D) and Hospital Anxiety and Depression Scale – Depression subscale (HADS-D) total scores.

Table 2.  Correlations between subject characteristics and depressive symptoms
 CES-D scoreHADS-D score
Depression
n (%)
No depression
n (%)
P-valueDepression
n (%)
No depression
n (%)
P-value
  1. CES-D, Center for Epidemiological Studies Depression Scale; HADS-D, Hospital Anxiety and Depression Scale – Depression subscale.

Setting      
 Inpatients23 (17.6)28 (21.4)0.00231 (23.7)20 (15.3)0
 Outpatients16 (12.2)64 (48.9)22 (16.8)58 (44.3)
Marital status      
 Single7 (5.3)8 (6.1)0.1286 (4.6)9 (6.9)0.969
 Married32 (24.4)84 (64.1)47 (35.9)69 (52.7)
Education level      
 High7 (5.3)23 (17.6)0.387 (5.3)23 (17.6)0.03
 Low32 (24.4)69 (52.7)46 (35.1)55 (42.0)
Pack year      
 Heavy smokers28 (21.4)57 (43.5)0.28137 (28.2)48 (36.6)0.33
 Light smokers11 (8.4)35 (26.7)16 (12.2)30 (22.9)
Figure 2.

Prevalence of depressive symptoms in patients with chronic obstructive pulmonary disease classified according to (inline image) the Hospital Anxiety and Depression Scale – Depression subscale (P = 0.032), (inline image) the Center for Epidemiological Studies Depression Scale (P = 0.001) and severity (GOLD stages).

Predictors of depressive symptoms

The results of the logistic regression analysis are presented in Table 3. In the case of CES-D, setting and severity exerted an effect such that depressive symptoms were more likely to occur in inpatients in those with severe COPD. For HADS-D, BMI, setting and education level exerted an effect such that depressive symptoms were more likely to occur in patients with a low BMI and low education levels. Likewise, in this study, the items that affected the assessment of depressive symptoms differed depending on the scale. No common factors between assessments were observed.

Table 3.  Odds ratios for the likelihood of depressive symptoms assessed using the CES-D and HADS-D
FactorComparisonCES-DHADS-D
Odd ratio95%CIP-valueOdd ratio95%CIP-value
  1. Data are adjusted odds ratios and 95% confidence intervals.

  2. BMI, Body mass index; CES-D, Center for Epidemiological Studies Depression Scale; Hospital Anxiety and Depression Scale – Depression subscale.

AgeBy 1-year increment1.010.96–1.070.6810.95–1.050.9
BMIBy 1-kg/m2 decrement1.120.98–1.270.091.131.06–1.38<0.01
Marital statusMarried vs Single1.630.47–5.680.440.470.12–1.790.26
Education LevelLow vs high1.880.66–5.350.244.651.57–13.70<0.01
Pack yearLight vs heavy0.640.26–1.610.346.710.29–1.690.44
SettingInpatients vs outpatients2.150.92–5.050.793.761.60–8.85<0.01
GOLD severityBy 1 severity increment1.671.05–2.720.031.240.79–1.940.35

DISCUSSION

The objective of this investigation was to examine the extent to which the prevalence of depressive symptoms differs following assessment with distinct screening tools (CES-D and HADS-D) in a group of patients with stable COPD and to examine the factors behind these differences. Based on the results of this study, the correlation between the total scores obtained with each scale is mild; furthermore, both tools are considered consistent as they assess the same constructive concept (depressive symptoms). However, the prevalence of depressive symptoms was 29.8% with CES-D and 40.5% with HADS-D; this difference was significant, indicating that the prevalence of depressive symptoms in COPD patients varies depending on the tool utilized. The prevalence of depressive symptoms increased in proportion to the degree of severity of COPD for both scales; however, with HADS-D, more patients with mild COPD were judged as having depressive symptoms. As depressive symptoms are similar to symptoms of physical disorder, the risk of artificially generated depression arises when assessing depressive symptoms in COPD patients. HADS was developed in order to resolve this issue; furthermore, much evidence indicates that HADS is superior to CES-D, which was developed for usage in the general population.15 But CES-D reflected the degree of severity to a greater extent in this study.

Comparison of the contribution of subject characteristics to the assessment of depressive symptoms with each scale revealed significant differences in terms of severity and setting for both CES-D and HADS-D. Previous research identified a correlation between depressive symptoms and severity of COPD19 as well as between depressive symptoms and prolonged hospitalization.20 The results of the present study showed a greater possibility of hospitalization for patients with more severe COPD, as well as more frequent findings of depressive symptoms in patients with severe COPD who were currently hospitalized. However, significant differences in ‘education level’ for only HADS were detected; these findings indicated a lack of consistency between the two scales. These results suggested that, despite the assessment of the same depressive symptoms, it is possible that assessments are conducted with a focus on different aspects.

Different factors impact the assessment of depressive symptoms with CES-D and HADS-D; consequently, logistic regression analysis was conducted. The results of this analysis show that only severity of COPD (CES-D), and BMI, setting and education (HADS-D) affected the assessment of depressive symptoms. Correlations between depressive symptoms and ‘severity’, ‘BMI’ and ‘setting’ have already been pointed out in preceding studies.7,8 The same tendencies were recognized in this study. However, although ‘education level’, was recognized with HADS-D, and was found to have an extremely strong weight in this study (OR = 4.65), fixed findings have not as yet been obtained from previous studies. In past research, a high level of education21 has been reported to be a risk factor for depressive symptoms in COPD patients; however, no relationship between education level and depressive symptoms in COPD patients5,10,22 has been described. Moreover, definitive findings regarding relevance between education level and depressive symptoms in COPD patients have not been obtained. Subjects in this study were elderly persons of a generation where it was not uncommon to find work following completion of junior high school; therefore, the higher numbers of patients with low education levels were not surprising. However, as this trend was not observed with CES-D, it is possible that education level exerted a strong impact on the scale score of HADS-D exclusively. Consequently, a strong possibility exists that an understanding of and determination of response for each of the questions was influenced by the education level of each person and may have caused depressive symptoms to be artificially judged as high.

In recent years, consequent to the focus on the impact of depressive symptoms on COPD, early detection and treatment of depressive symptoms in COPD patients are considered important in primary care; moreover, tools enabling accurate assessment of depressive symptoms unique to COPD patients are required. For example, past investigations involving patients with rheumatism23 noted that HADS-D, in comparison with CES-D, has greater validity for the assessment of depressive symptoms in these patients. When assessing identical depressive symptoms, expression of depressive symptoms unique to a particular disorder is observed; thus, it is essential to examine screening tools that are adapted to particular disorders.

Screening tools for the assessment of depressive symptoms in COPD patients that have been developed based on diagnostic criteria for depression in the field of psychiatry are currently being applied. The assessment of depressive symptoms in COPD patients is often undertaken by medical care staff or persons who possess no knowledge or skills related to psychological assessment; consequently, screening tools that can be employed regardless of age, sex and education level are desirable. In the future, the implementation of multiple investigations regarding reliability and adequacy, including in relation to other screening tools applicable to COPD patients, is necessary. Moreover, depending on the case, the development of tools for screening depressive symptoms exclusively in patients with COPD is required. Although screening for depression in the primary care setting in populations such as patients with COPD has the capacity to enhance both the recognition of the problem and the initiation of treatment, in the absence of case management being provided by specialist mental health professionals, the outcome of depression in the primary care setting is unlikely to change. The small number of individuals with mild COPD was a limitation of the current investigation. In addition, the samples consisted of those obtained from only four local prefectures; moreover, most of the subjects were characterized by low educational levels. It is possible that the bias of this sample resulted in the strong impact of educational levels on depression in the application of HADS-D. A limitation exists with respect to generalizing the results of this study. In the future, the acquisition of broader data, including that for subjects from metropolitan areas and that from individuals with high educational levels, is necessary. Further, we did not use a validated diagnostic instrument, such as the structured clinical interview DSM and thus the real prevalence of depressive disorder in the study population is unknown. Finally, this study assessed associations between CES-D and HADS-D. Further research is needed to evaluate the capacity of these scales to detect changes in the psychological states of individuals with COPD.

This study focused on CES-D and HADS-D, which are representative screening tools for the assessment of depressive symptoms in patients with COPD, and examined the extent to which prevalence of depressive symptoms differs between these tools and the factors that account for such differences. Findings revealed that, regardless of assessment of the same patient, prevalence of depressive symptoms differs and HADS identifies a higher prevalence of symptoms. Reasons for this observation include the fact that HADS-D is strongly affected by the education level of the patients.

ACKNOWLEDGMENTS

The authors wish to thank the following persons for their assistance in the recruitment of COPD patients: Dr Toru Tsuda (Tsuda Hospital, Kitakyushu, Fukuoka) and Dr Naoto Rikitomi (Nagasaki Kokyuki Rehabilitation Clinic, Isahaya, Nagasaki). The authors would also like to thank Dr Sue Jenkins (School of Physiotherapy, Curtin University of Technology, Perth, Australia) for her help in proofreading this manuscript.

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