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Epidemiology of Depressive Disorders in Korea Maeng Je Cho, M.D., Ph.D.1*, Jun Young Lee, M.D.2 Department of Psychiatry & Behavioral Science, Seoul National University College of Medicine, Seoul, Korea, Department of Psychiatry, Seoul National University College of Medicine, Boramae Hospital, Seoul, Korea
1 2
Abstract: Prevalence rates of major depression between 3.5-4% and those of depressive symptoms were between 7.4-38.9% in Korea. The low rates of major depression and the high rates of depressive symptoms seem to be due to different response attitude to the interviewer and self–reporting instrument, which could be explained by Confucian cultural influence in Korea. Depressive mood, loss of interest, insomnia and fatigue were common symptoms in persons with major depression. The symptom profiles of major depression were not different from those of western countries. The prevalence rates of major depression in the elderly of Korea were high. These high rates may be related with recent sociocultural stresses in the elderly of Korea. Risk factors of major depression were woman, old age, recent cohort, disrupted marriage, low socioeconomic status and rural residence. Old age and rural residence are rarely reported as risk factors in other countries. Academic failure was an important correlate in adolescent depression. Course, disability and service use were rarely reported in persons with major depression in Korea. Key words: depression, prevalence rate, Korea Psychiatr Invest 2005; 2 (1): 22-27
Introduction Major depressive disorder is a very disabling disease, and at the same time considerablely burdensome on Correspondence: Maeng Je Cho, M.D., Ph.D. Department of Psychiatry, Clinical Research Institute, Seoul National University College of Medicine & Hospital, 28 Yongon-Dong, Chongno-Gu, Seoul, Korea (110-744) Tel: +82-2-2702-3155, Fax: +82-2-744-7241, E-mail :
[email protected]
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society. Global Burden of Disease for the year 2000 analysis reported that minor depression was ranked as the fourth leading cause of burden on society among all diseases and would be ranked as the leading cause in 20101. To decrease the burden of major depression on community, it is necessary to know its prevalence, course and correlates in community. Community-based large sample, standardized interview tools and widely agreed diagnostic criteria are essential for getting precise epidemiologic data. From 1980, community surveys on the estimation of prevalence of psychiatric illness including major depression have been conducted using fully structured instruments based on Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria or International Statistical Classification of Diseases and Related Health Problems (ICD) criteria in many countries. Epidemiological Catchment Area study (ECA)2 and National Comorbidity Survey (NCS)3 were conducted to estimate the prevalence of psychiatric disorders in USA. In Korea, two nationwide large community-based psychiatric epidemiologic studies based upon fully structured instruments were conducted. At first, Lee et al. conducted the community-based psychiatric epidemiologic study by using Korean Diagnostic Interview Schedule (DIS) based on the DSM-III diagnosis in 1984 4 . In the next place, Korean Epidemiologic Catchment Area study (KECA) was conducted in 2001 using Korean-Composite International Interview version 2.1 (K-CIDI) based on the DSM-IV5, 6. This review will focus on symptoms, prevalence, risk factors, course, disability of major depressive disorder based on two community-based psychiatric epidemiologic studies and other depression studies in Korea.
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Diagnosis and symptoms Current classification systems: Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV)7 and International Classification of Diseases, tenth revision (ICD-10) 8 have operational criteria for depression which have led to considerably improved reliability and consensus9. the DSM-IV includes three key criteria of major depressive disorder: 1) at least 5 of symptoms listed, 2) significant distress or significant impairment in functioning, and 3) a minimum of 2 weeks duration. The DSM-IV requires at least one of the symptoms: diminished interest/pleasure or depressed mood and at least 5 of the following symptoms: depressed mood, diminished interest or loss of pleasure in almost all activities, sleep disturbance, weight change or appetite disturbance, decreased concentration or indecisiveness, suicidal ideation or thoughts of death, psychomotor agitation or retardation, fatigue or loss of energy, feelings of worthlessness or inappropriate guilt. The ICD-10 requires at least two of the symptoms: depressed mood, loss of interest or pleasure, decreased energy or increased fatigue and at least 2 of the following symptoms: loss of confidence or self-esteem, unreasonable feelings of self-reproach, recurrent thoughts of death or suicide, complaints of diminished ability to think or concentrate, change in psychomotor activity, sleep disturbance, change in appetite. Symptoms profiles of major depression make little difference among countries. Depressed mood, loss of interest, insomnia and fatigue were symptoms common in most persons with major depression at all countries10. In Korea, depressed mood, loss of interest, insomnia, fatigue, and concentration difficulty appeared in more than 80% of persons with major depression in the recent Korean Epidemiologic Catchment Area (KECA) study (figure 1). We tested threshold levels for each depressive symptom using item response theory analysis. The each depressive threshold was higher than other countries, but the symptom patterns were similar with other studies using the CIDI. We could not find any fallacies of diagnostic criteria for major depression defined by the DSMIV among Korean depressive symptom profiles. Fatigue, concentration difficulties, and sleep disturbance appeared more frequently in mild depression, while psy-
FIGURE 1. Prevalence of symptoms in persons with major depression based on KECA study
FIGURE 2. Threshold values from Item Response Theory analyses with 95% confidence intervals for each depressive symptom in KECA study
chomotor change, thoughts of death/suicide, and feelings of worthlessness/guilt were more prominent in severe depression (figure 2)11.
Prevalence Prevalence of major depressive disorder was mostly estimated by standardized interview instruments: the Diagnostic Interview Schedule (DIS) and the Composite International Diagnostic Interview (CIDI). Prevalence of current depressive symptoms was mostly estimated by brief screening instruments: the Center for Epidemiologic Studies Depression Scale (CES-D), the Beck Depression
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Inventory (BDI), the Older American’s Research and Service Center Instrument (OARS), and the Geriatric Depression Scale (GDS). The prevalence rates of major depression and depressive symptoms in Korea are shown in Table 1 and 2. The prevalence rates of major depression varied widely among countries and the prevalence rates were low in East Asia. Using DIS based on the DSM-III, The CrossNational Collaborative Group from 10 countries estimated the prevalence rates of major depression from 1.5% in Taiwan to 19.0% in Lebanon for life-time and 0.8% in Taiwan to 5.8% in New Zealand for 12 months 10. In Korea, the life-time prevalence rate of major depression was 2.8% and the annual prevalence rate was 2.3% based on the DSM-III4. Using the CIDI based on the DSM-III-R or the DSMIV, the International Consortium of Psychiatric Epidemiology from 10 countries reported the lifetime
prevalence rates of major depression from 3% in Japan to 16.9% in the US and the annual prevalence rates of major depression from 1.2% in Japan to 10% in the US12. In Korea, the life-time prevalence rate of major depression was 4.3% and the annual prevalence rate was 1.7% based on the DSM-IV5. It is not certain whether these low prevalence rates in Korea were due to methodological, sociological, or biological differences between Korea and other countries. When using a self-reporting depression scale, however, the rates of symptoms of depression in Korea were high. In a nationwide sample of Korean adults, 25.3% had scores above the cutoff point of 16 (probable depression) on the CES-D scale13. Most studies in other countries reported the prevalence rates of probable depression between 10-28%14, 15, 16. Cho et al. pointed that due to Confucian cultural influence, Koreans were quite reluctant to express their affect when being interviewed and
TABLE 1. Prevalence rates of depressive disorders in Korea
Authors
Date
Place
Age
No
Lee et al Lee et al Cho et al
1990 1989 2004
Nationwide Kangwha Nationwide
18-64 18-64 18-64
5100 1450 6242
Seo et al Hong et al Lee et al Bae et al
1999 2000 2000 2001
Yunchon-Gun Ulsan Kwachon Incheon
65+ 65+ 65+ 65+
Instrument
MD
DD
DIS, DSM-III DIS, DSM-III CIDI, DSM-IV
3.5 1.3 4.0
1.9 1.8 0.5
1134 712 500 853
PAS, Psych interview PAS, Psych interview GDS, Psych interview CIDI, DSM-IV
7.5 7.3 7.8 4.2
2.0 3.0 3.9
MD: Major depressive disorder, DD: Dysthymic disorder TABLE 2. Prevalence rates of depressive symptoms in Korea
Authors
Date
Place
Age
No
Instrument
Depressive symptoms
Cho et al
1998
Nationwide
18-64
3711
CESD (15/16 cut-off) CESD (24/25 cut-off)
25.3 8.7
Song et al
1999
Cho et al
2001
Seoul Tashkent Bucheon
13-18 13-18 13-18
838 652 1972
BDI (18/19 cut-off) BDI (18/19 cut-off) CESD (15/16 cut-off) CESD (24/25 cut-off)
26.5 7.4 38.9 21.2
Lee and Shin Cho et al Cho et al Oh et al Kim et al
1989 1998 1998 1998 2001
Kangwha Seoul Institution Kwangju Kwangju
65+ 65+ 65+ 65+ 65+
1005 447 153 1201 1134
OARS CESD (24/25 cut-off) CESD (24/25 cut-off) GDS (17/18 cut-off) GDS (13/14 cut-off)
9.7 18.1 23.5 10.0 33.0
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in result, the diagnostic threshold was very high 13, 17. Difference of the prevalence rates of major depression between Korea and other countries seems to be due to difference in diagnostic threshold of major depression between Korean and other countries18. Although incidence studies are important to study risk factors of major depression, the incidence data were rarely reported. Annual incidence rate of first-onset major depression was 1.6 per 100 in the ECA study19. In Korea, the incidence data of major depression were only surveyed in the elderly. The one-year incidence rate of depression (including first-onset depression and recurred depression after 1 year) was 5.1% in a rural elderly community. It is a very high rate comparing with other countries20.
Risk Factors Female, recent cohort (younger generation), marital disruption, family history of major depression were known as risk factors of major depression in most countries. In Korea, the significant correlates of major depressive disorder were female, age over 50, recent cohort, disrupted marriage, fewer than 13 years of education, being unemployed, and rural habitat13, 21. Higher risk of major depression in women was reported in most countries22, 23. In Korea, consistently higher rates of major depression in women have been reported4, 12, 13, 21, 24 . The ratio of rates of major depression in women to men was about 2 : 1 (Figure 3). It seems that women had more persistent courses of major depression or expressed their emotion more easily instead of having
real higher rates of major depression than men. But, in incidence study of major depression, the annual incidence rate of women was almost twice higher than that of men19. It seems that women had a real increased risk of major depression. Recently, an increase in the prevalence rates of major depression was observed in recent cohort (younger generation) in most countries25. This cohort effect on cumulative lifetime prevalence was also observed by using retrospective reports about age of onset in Korea21. Age of onset was lowered and the cumulative lifetime prevalence began to rise with an increasingly steep slope in more recent cohorts. The odds ratio for the youngest cohorts comparing with the oldest cohorts was 17. It is consistent with reports of higher prevalence rates of depressive symptoms in Korean adolescents26, 27. Marital status was associated with rates of major depression in most depression studies. Persons who were divorced, separated, or widowed had a risk for lifetime major depression two times higher than those who were married or never-married in Korea21, 26. The stress of marital disruption may predispose person to major depression or vice versa28. Low level of education and unemployment were significant risk factors in NCS 3, and Korean studies of depression showed same results13, 21. Especially, job loss was an important correlate of current major depression in KECA study5. This result could be related that it was difficult for depressed persons to find a job. Urban-rural difference in prevalence of major depression was controversial 3, 29, 30. In Taiwan, small cities showed higher major depression rates than rural areas and metropolitan cities29. Lee et al. reported no difference in rates of major depression between urban areas and rural areas31, but Cho et al. reported higher prevalence rate of major depression in rural areas. Cho and his colleagues suggested that the stresses of rapid decrease of population in rural areas from 40% in 1980 to 10% in 2000 and rapid decrease of income should predispose rural individuals to major depression13.
Special Population Adolescent depression FIGURE 3. Prevalence rates of major depression by sex and age in KECA study
Lewinsohn et al. reported the point and lifetime prevalence rate of major depression as 2.9% and 20.4%
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respectively32. In Korean adolescents, there has been no report to estimate rates of major depression. Cho et al. estimated the rates of depressive symptoms in adolescents aged 13 to 18 as 26.5%. They reported rates of depressive symptoms in boys and girls were 34.3% and 47.5% respectively and the boy to girl ratio was 1.4. Song et al. reported the rates of depressive symptoms in adolescents aged 13 to 18 as 26.5%. The boy to girl ratio was 1.5. The prevalence rate of depressive symptoms in adolescents was high and the boy to girl ratio was relatively low. The important risk factor of depression in adolescents was dissatisfaction with their school record degrees26. Female, academic failure, meeting friends less frequently, presence of chronic physical illness, and interpersonal problems with parents, or friends were correlates of depressive symptoms in adolescents27. Geriatric depression In ECA and NCS study in the US, major depression rates decreased with age25, 30. In most studies which estimated prevalence of major depression in old age, the prevalence rates were less than 5%33. But it is not the fact in Korea. Higher prevalence of major depression in older age was not observed by 198434. But the prevalence of major depression was higher over the age of 50~59 years in KECA study in 200021 (Figure 3). Suh et al. reported prevalence rate of major depression in old age as 7.5%, Hong et al. reported as 7.2%, and Lee et al. reported as 7.8%24, 35. Only Bae et al. reported prevalence rate of major depression in old age below 5%. Using the CES-D (24/25 cut-off value), prevalence rate of definitive depressive symptoms was 8.3% in 15-64 year-old persons, but was 18.1% over 65 year-old persons13, 36. Oh et al. reported prevalence rate of depressive symptoms as 10%37 using GDS (17/18 cut-off value) and Kim et al. reported as 33.0% using GDS (13/14 cut-off value)38. This high rate of major depression in the Korean elderly seemed to be due to severe stress from rapid sociocultural change and economic difficulties21. It is concordant with higher suicidal rates in older age recently39. The rates of major depression in men seemed to be rising with age but in women, the rates of major depression seemed not to change with age. Physical illness was a major risk of major depression in the elderly. Kim et al. reported prevalence rate of major depression in the elderly medical inpatients as 7% 40, and Han et al. reported that 19.7% of elderly
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patients in hospital were diagnosed as major depressive disorder41.
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