Research report
A nationwide survey on the prevalence and risk factors of late life depression in South Korea

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Abstract

Objective

This study aimed to estimate prevalence rates and risk factors of LLD among a large nationwide sample of Korean elders in South Korea.

Method

Of 8199 randomly sampled Koreans aged 65 years or more, 6018 participated (response rate = 73.4%). Using the Korean version of the short form Geriatric Depression Scale (SGDS-K), we classified individual scoring 8 or 9 as having possible depression and those scoring  10 as having probable depression.

Results

The age-, gender-, education-, and urbanicity-standardized prevalences were 10.1% (95% CI = 9.3–10.8) for possible depression, 17.8% (95% CI = 16.8–8.7) for probable depression, and 27.8% (95% CI = 26.7–29.0) for overall depression. Poverty, living alone, low education, illiteracy, smoking, history of head trauma, and low Mini Mental Status Examination score were associated with greater risk of depression, while mild alcohol use and moderate to heavy exercise were associated with lower risk of depression. However gender difference in the risk of depression was not found.

Conclusion

LLD is decidedly common in South Korea. It was associated with various sociodemographic and clinical factors, some of which are amendable through policy actions. This study was limited by use of the SGDS-K rather than a standardized clinical interview.

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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