Research reportA nationwide survey on the prevalence and risk factors of late life depression in South Korea
Introduction
Late life depression (LLD) is likely to become one of the most significant public health problems in Asian countries, including in Korea, where the numbers of elderly persons are increasing at a remarkable rate. Although depression is one of the most common and treatable mental illnesses, LLD often goes under-recognized and undertreated due to its subsyndromal features and complicated etiologies. The burden of inadequately treated LLD is substantial since LLD, even if subsyndromal, is as detrimental to well-being, and as disabling, as major depressive disorder (MDD) is (Beekman et al., 1997). Recently, researchers and clinicians have been paying more attention to LLD due to a steep rise in the suicide rate among elderly Koreans. Recent statistics show South Korea has the highest suicide rate among Organization for Economic Cooperation and Development (OECD) member nations (KNSO, 2010).
One estimate gave the prevalence of MDD among the elderly as 5.37% in Korea, higher than the prevalences in most Western countries and in other Asian countries (Park et al., 2010). MDD, however, might be just the tip of the iceberg, since a considerable proportion of the elderly people with clinically significant depressive symptoms do not meet the rigorous MDD diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Although no agreement exists on a gold standard for defining this clinically-significant but subsyndromal depression, researchers and clinicians have often used self-rating questionnaires for depressive symptoms, such as the Geriatric Depression Scale (GDS) (Yesavage et al., 1982), its short form (SGDS) (Sheikh et al., 1986), and the Center for Epidemiologic Studies Depression Scale (CES-D), to capture subsyndromal and syndromal depression for individuals in later life.
In Korea, LLD that encompasses MDD and subsyndromal depression has rarely been studied. Two studies using either the GDS or the SGDS (Cho et al., 1998, Kim et al., 2002) estimated the prevalence of LLD as 13.4% and 15.8%, respectively. However, these studies were conducted over 10 years ago on a small regional sample. In the present study, we investigated the prevalence and risk factors of LLD, as defined by SGDS score, among a large nationwide sample of Korean elders.
Section snippets
Subjects
This study was conducted as part of the Nationwide Survey on Dementia in Korea (NaSDeK) (Kim et al., 2011). The method of estimating sample size was described in detail in our previous work (Kim et al., 2011). To capture national variations, we selected 15 districts across the country. Within these, 13 hospitals had the responsibility of conducting the survey in their nearby districts. The hospitals randomly selected villages within their corresponding districts so as to cover about 5000
Demographical characteristics of respondents
6018 subjects (age = 73.41 ± 6.27 years; female = 60.00%) participated in the study (response rate = 73.4%). The response rate was higher in rural areas than in urban regions (77.6% versus 71.4%, P < 0.001). Responders and non-responders had no significant differences in gender or age distributions (P = 0.52 for gender, P = 0.56 for age). Of the 6018 participants, 1054 had probable depression, and 609 had possible depression. Participants with possible or probable depression were older, less educated (P < 0.001
Discussion
This study estimates prevalence rates for possible and probable depression in Korean elders as 10.1% and 17.8%, respectively. Although both possible and probable depression increase in prevalence at greater ages, this age-associated depression risk peaks at 75–79 years and decreases thereafter. Although both possible and probable depression were more prevalent in women than in men, this female preponderance lacks statistical significance after we adjust for other risk factors. Probable
Role of funding source
This study was supported by a research grant from the Ministry of Health, Welfare, and Family Affairs, Korea (Grant No. 07-2008-0270) and a grant of the Korean Health Technology R&D Project, Ministry for Health, Welfare, and Family Affairs, Republic of Korea (Grant No. A092077).
Conflict of interest
The authors have no conflicts of interest to report in relation to the research presented in this manuscript.
Acknowledgments
We thank all the participants who so generously gave us their time and support.
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