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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.
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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.