The Clinical Research Center for Depression (CRESCEND) study is a 9-year observational collaborative prospective cohort study for the clinical outcomes in participants with depressive disorders in Korea. In this study, we examined the baseline characteristics of the depressive participants as the hospital-based cohort.
Participants were assessed using various instruments including the Clinical Global Impression scale, 17-item Hamilton Depression Rating Scale (HDRS-17), Hamilton Anxiety Rating Scale, Brief Psychiatric Rating Scale, Social and Occupational Functioning Assessment Scale, Beck Depression Inventory-Second Edition, Scale for Suicide Ideation, and World Health Organization Quality of Life assessment instruments-abbreviated version. Also, personal histories of medical and psychiatric illnesses and the range of socio-epidemiologic and clinical data were collected from each participant.
One thousand one hundred eighty three participants were recruited from 18 hospitals. The mean age of the participants was 47.9±15.9 year-old, 74.4% were female, 82.9% had been diagnosed of major depressive disorder, 40.9% were experiencing their first depressive episode, and 21.4% had a past history of suicide attempts. The majority (85.3%) of the participants were moderately to severely ill. The average HDRS-17 was 19.8±6.1. Significant gender differences at baseline were shown in age, education, marriage, employment, religion, and first depressive episode.
The baseline findings in the CRESCEND study showed some different characteristics of depression in Korea, suggesting a possibility of ethnic and cultural factors in depression.
Depression [especially, major depressive disorder (MDD)] is a common psychiatric disorder typically associated with significant suffering, high morbidity and mortality rates, and psychosocial impairment.
Depression is associated with a wide range of negative consequences, including a significant worsening of comorbid medical conditions, a high mortality risk related to suicide, and a socioeconomic burden resulting from functional impairment.
Depression is a clinical syndrome having pronounced heterogeneity in risk factors, clinical presentation, clinical course, and treatment responsiveness.
In Korea, depression is also a common psychiatric disorder. The 12-month prevalence and the lifetime prevalence rates of the MDD are 1.7% and 4.3%, respectively.
Despite the relatively low prevalence of depression, depression has a deep impact on Korean society. The socioeconomic burden of depression in Korea cost over 1.5 billion US dollars in 2004.
The Clinical Research Center for Depression (CRESCEND) study is a long-term (phase 1, 1-year; phase 2, 8-year) observational collaborative prospective cohort study of clinical outcomes in participants with depressive disorders. The primary objective of the CRESCEND study is to investigate the clinical risk factors, courses, and outcomes of depression in the Korean society. The secondary objectives include evaluating the changes in the quality of life and the risk of suicide according to the clinical course of depression, as well as the actual social and economic burden of depression, and providing the clinical evidence for the development of Korean-specific diagnostic tools and clinical practice guidelines. The CRESCEND study is the first nationwide long-term observational prospective cohort study investigating actual medical care for depressive disorders to be conducted in Korea. The aims of this article are to introduce an overview of the CRESCEND study as well as to provide the baseline socio-epidemiologic and clinical findings of the participants.
From January 2006 to August 2008, 1,183 participants were enrolled in the CRESCEND study. The 18 hospitals collaborating in this study included psychiatric departments of 16 university hospitals and 2 general hospitals from all over Korea. Each hospital completed a predetermined clinical report form of the participants in each visit and recorded the data in the homepage of the CRESCEND (
The inclusion criteria for the study participants were 1) an age over 7 years and 2) a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV),
The consent form and the research protocol were approved by the respective university and/or hospital institutional review boards. All participants reviewed the informed consent form and signed in the presence of research staff before participating in the study.
The CRESCEND study included two phases, I and II, with a total of 9 follow-up years. The phase I study period was 1 year. In phase I, if the eligible participants entered the study at baseline, each participant visited the hospital and was assessed at 1, 2, 4, 8, 12, 24, and 52 weeks. The phase II study, an extension study from 1 year to 9 years (total 8 years), in which the participants will be evaluated annually.
At baseline, the participants underwent a diagnostic evaluation and a retrospective personal history of their medical or psychiatric illnesses and treatment. Also, a variety of socio-epidemiologic and clinical data were collected. The clinical, social, and functional outcomes associated with the treatment including clinician- and self-administered measures were evaluated at each visit.
The clinician-administered measures included the Clinical Global Impression scale (CGI),
The CGI, which is widely used of extant brief assessment tolls in psychiatry, is a 7-point observer-rated scale that measures illness severity and global improvement or change. The HDRS-17 is the most widely used clinical-administered depression assessment scale. Each item pertains to symptoms of depression experienced over the past week. The HARS is a 14-item clinician-administered rating scale and provides an overall measure of the severity of global anxiety including psychic and somatic symptoms. The BPRS is an 18-item clinician-rated tool designed to assess change in severity of psychopathology. The items of the BPRS focus on symptoms that are common in psychotic disorder including schizophrenia and other psychotic disorders as well as those found in severe mood disorders. The SOFAS is a 100-point, single-item scale that rates functioning on a hypothetical continuum of mental health to mental illness. It focused on the individual's level of social and occupational functioning and is not directly influenced by psychological symptoms.
The self-administered measures consisted of the Beck Depression Inventory-Second Edition (BDI-II),
The BDI-II a 21-item self-report instrument intended to assess the existence and severity of symptoms of depression. It was revised in 1996 to be more consistent with DSM-IV criteria for depression than the original BDI. The SSI is a 21-item, 3-point Likert self-administered scale that asks about suicide ideation during the past week. The severity of suicide ideation is calculated by summing the rating for the first 19 items. The WHOQOL-BREF is a 26-item instrument to assess the quality of life, which measures the following broad domains: physical health, psychological health, social relationships, and environment. It is a shorter version of the original WHOQOL that may be more convenient for use.
Twice a year, the raters in each individual hospital participated in formal consensus meetings concerning the use of the rater-administered assessment instruments including the HDRS-17, the HARS, the BPRS, and the SOPAS. The consensus meetings consisted of an observation of the administration of the evaluations by an experienced supervisory psychiatrist and an actual administration via videotapes featuring standard MDD patients with or without psychotic features.
All data were presented as number (percentage) for categorical variables and as mean (standard deviation) for continuous variables. Descriptive statistics were used to characterize the study participants at baseline in
A total of 1,183 participants with depression were enrolled in this study. The sociodemographic characteristics of the participants at baseline are shown in
The clinical characteristics of the participants at baseline were summarized in
Overall, the participants were moderately to severely ill (1,009 persons, 85.3%), based on CGI-severity. Only 29 depressive participants (2.5%) were in the remission state (HDRS-17 ≤7) at baseline. The mean±standard deviation scores of CGI-severity in MDD, dysthymic disorder and depressive disorder NOS were 4.7±1.0, 3.8±1.0, and 4.4±1.0, respectively. Also, the mean±standard deviation scores of HRDS-17 among the three groups were 20.2±6.0, 16.5±5.7, and 18.2±6.0, respectively.
The proportion of women (78.4%) and men (78.2%) who were recruited from the outpatient setting were similar. Women who had experienced their first depressive episode at baseline were more prevalent in this sample than men, but it was not significantly different after adjusting for age (p=0.453). Men had a somewhat earlier onset of their first depressive episode (mean of 43.1 years) than women (mean of 44.8 years, p= 0.016, adjusted for age). The proportions of women and men with respect to the number of depressive episodes and the presences of current general medical comorbidities, past history of suicide attempts, and family history of depression were similar. Also, mean scores of individual psychiatric measures at baseline did not differ by gender in this study.
The CRESCEND study is the first long-term prospective collaborative observational cohort study investigating the natural course and outcome of depressive patients to be conducted in Korea. The participants were enrolled in 18 hospitals from all over Korea and the distribution of participated hospitals reflected the spread of population in Korea. Though a number of naturalistic cohort studies of depression have been conducted all over the world (especially in the Western world), there are still numerous questions about the clinical and socioeconomic outcomes resulting from actual clinical and medical practices for depression; the results of those studies are difficult to extend to Eastern societies given broad ethnic and cultural differences. The CRESCEND study was designed to investigate the more long-term comprehensive outcomes of depression in order to overcome the limitations stated above. In this report we have described the research methodology of the CRESCEND study and reported the baseline findings from the depressive samples.
Some interesting baseline findings were found in the CRESCEND study.
Though the age distribution of this study was statistically normal, the child and adolescent depressive participants (≤17 year-old) were very few (2.1%), but the proportion of geriatric depressive participants (≥65 year-old) was relatively high (16.7%). This finding may be an artifact of methodological problems for specific age groups such as parental reluctance to permit children to participate in the study and indirectly, reflection of recent lower birth rate and more increased aged population in Korea. The female prevalence in this study was 74.4%. The gender ratio of 2.9 seen in women vs. men willing to enroll in this study is higher than that of several previous reports,
Several distinctive clinical findings of depression at baseline were revealed in the CRESCEND study. First, the mean age at onset of the first depressive episode in this study was 44.9 years old, which is higher than that of previous studies.
In these baseline results, some gender differences noted among the depressive participants in socioepidemiologic data (e.g., higher education level in males, higher employment in males, and higher religion-seeking tendency in females) may be influenced in part by cultural gender differences in current Korean society. These findings were inconsistent compared to Western countries.
This study has several limitations. While the cross-sectional observational methodology is useful for the better understanding of real-life clinical practice, there are limitations on the causal inferences that can be drawn due to uncontrollable confounding factors, selection bias, and reverse causality. Though the results of this study were cross-sectional and observational, the CRESCEND study itself was designed as a prospective cohort study. Thus, further analyses of the longitudinal data may overcome several limitations. In this study, nearly three-fourths of participants with depression were enrolled from outpatient settings. This fact may have resulted in a selection bias that influenced findings of symptom severity, the presence of psychotic symptoms, and the frequency of subtypes of depression including dysthymic disorder and depressive disorder NOS. Only 2.0 percent of depressive participants, all of whom were enrolled from the inpatient setting, had psychotic features. However, the differences in depressive symptom severity at baseline between inpatients and outpatients were not significant in this study.
The CRESCEND study is the first long-term hospital-based prospective collaborative observational cohort study investigating the
This research was supported by a grant of the Korea Health 21 R&D, Ministry of Health and Welfare, Republic of Korea (A050047).
The list of 16 university hospitals and 2 general hospitals which participate in the CRESCEND study is below;
Affiliated hospitals of the Catholic University of Korea (Seoul St. Mary's Hospital, Seoul; St. Mary's Hospital, Seoul; Uijeongbu St. Mary's Hospital, Uijeongbu; Incheon St. Mary's Hospital, Incheon; St. Vincent's Hospital, Suwon); Chonnam National University Hospital, Gwangju; Chonnam National University Hwasun Hospital, Hwasun; Chosun University Hospital, Gwangju; Hanyang University Hospital, Guri; Inje University Pusan Paik Hospital, Busan; Kangwon National University Hospital, Chuncheon; Keimyung University Dongsan Medical Center, Daegu; Korea University Anam Hospital, Seoul; Sunchunhyang University Bucheon Hospital, Bucheon; Sunchunhyang University Hospital, Seoul; Sungkyunkwan University Kangbuk Samsung Hospital, Seoul; Bongseng Memorial Hospital, Busan; Maryknoll Medical Center, Busan.
Socioepidemiologic characteristics at baselin
*cutoffs of 10,000 and 30,000 US dollars mean the approximate minimum and average costs of a family of 4 members, respectively, in 2006 in Korea (National Statistics Office, 2007)
Clinical characteristics at baseline
HDRS-17: 17-item Hamilton Depression Rating Scale, BDI-II: Beck Depression Inventory-Second Edition, HARS: Hamilton Anxiety Rating Scale, SSI: Scale for Suicide Ideation, CGI-S: Clinical Global Impression scale-Severity, SOFAS: Social and Occupational Functioning Assessment Scale, WHOQOL-BREF: World Health Organization Quality of Life assessment instruments-abbreviated version
Gender differences of the baseline characteristics
*adjusted for age. HDRS-17: 17-item Hamilton Depression Rating Scale, BDI-II: Beck Depression Inventory-Second Edition, HARS: Hamilton Anxiety Rating Scale, SSI: Scale for Suicide Ideation, CGI-S: Clinical Global Impression scale-Severity, SOFAS: Social and Occupational Functioning Assessment Scale, WHOQOL-BREF: World Health Organization Quality of Life assessment instruments-abbreviated version