Socio-economic inequalities in mental health and their determinants in South Korea

Suicide rates in South Korea (hereafter ‘Korea’) have seen a sharp upward trend over the past decade, and now stand amongst the highest in OECD countries. This raises urgent policy concerns about population mental health and its socioeconomic determinants, an area that is still poorly understood in Korea. This thesis sets out to investigate socio-economic inequalities in the domain of mental health, particularly for depression and suicidal behaviour, in contemporary Korea. The thesis first evaluates the extent of income-related inequality in the prevalence of depression, suicidal ideation and suicide attempts in Korea and tracks their changes over a 10-year period (1998-2007) in the aftermath of the 1997/98 economic crisis. Based on four waves of the Korea National Health and Nutrition Examination Survey (KHANES) data, concentration indices reveal a growing trend of pro-rich inequalities in all three outcomes over this period. To understand the potential impact of the observed widening income inequality, the next empirical investigation examines whether income inequality has a detrimental effect on mental health that is independent of a person’s absolute level of income. Due to the paucity of time series data, the analysis focuses on an association between regional-level income inequality and mental health, using the 2005 KHANES data. The results provide little evidence to support the link between the two at regional level. The thesis pays special attention to suicide mortality rates given their disconcerting trend in contemporary Korea. Using mortality data for 2004-2006, the third empirical investigation first elucidates the spatial patterns of suicide rates, highlighting substantial geographical variations across 250 districts. The results of a spatial lag model suggest that area deprivation has an important role in shaping the geographical distribution of suicide, particularly for men. The final empirical investigation sets out to understand the suicide trend in Korea in the context of other Asian countries (Hong Kong, Japan, Singapore, and Taiwan), using both panel data and country-specific time-series analyses (1980-2009). Despite similarities in geography and culture, the suicide phenomenon is unique to Korea, particularly for the elderly. The overall findings suggest that low levels of social integration and economic adversity may in part explain the atypical suicide trend in Korea

Predictors of remission in the treatment of major depressive disorder: real-world evidence from a 6-month prospective observational study

BACKGROUND: This study examined potential predictors of remission among patients treated for major depressive disorder (MDD) in a naturalistic clinical setting, mostly in the Middle East, East Asia, and Mexico. METHODS: Data for this post hoc analysis were taken from a 6-month prospective, noninterventional, observational study that involved 1,549 MDD patients without sexual dysfunction at baseline in 12 countries worldwide. Depression severity was measured using the Clinical Global Impression of Severity and the 16-item Quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR16). Depression-related pain was measured using the pain-related items of the Somatic Symptom Inventory. Remission was defined as a QIDS-SR16 score ≤5. Generalized estimating equation regression models were used to examine baseline factors associated with remission during follow-up. RESULTS: Being from East Asia (odds ratio [OR] 0.48 versus Mexico; P<0.001), a higher level of depression severity at baseline (OR 0.77, P=0.003, for Clinical Global Impression of Severity; OR 0.92, P<0.001, for QIDS-SR16), more previous MDD episodes (OR 0.92, P=0.007), previous treatments/therapies for depression (OR 0.78, P=0.030), and having any significant psychiatric and medical comorbidity at baseline (OR 0.60, P<0.001) were negatively associated with remission, whereas being male (OR 1.29, P=0.026) and treatment with duloxetine (OR 2.38 versus selective serotonin reuptake inhibitors, P<0.001) were positively associated with remission. However, the association between Somatic Symptom Inventory pain scores and remission no longer appeared to be significant in this multiple regression (P=0.580), (P=0.008 in descriptive statistics), although it remained significant in a subgroup of patients treated with selective serotonin reuptake inhibitors (OR 0.97, P=0.023), but not in those treated with duloxetine (P=0.182). CONCLUSION: These findings are largely consistent with previous reports from the USA and Europe. They also highlight the potential mediating role of treatment with duloxetine on the negative relationship between depression-related pain and outcomes of depression

Clinical consequences of switching from olanzapine to risperidone and vice versa in outpatients with schizophrenia: 36-month results from the worldwide schizophrenia outpatients health outcomes (W-SOHO) study

BACKGROUND: With many atypical antipsychotics now available in the market, it has become a common clinical practice to switch between atypical agents as a means of achieving the best clinical outcomes. This study aimed to examine the impact of switching from olanzapine to risperidone and vice versa on clinical status and tolerability outcomes in outpatients with schizophrenia in a naturalistic setting. METHODS: W-SOHO was a 3-year observational study that involved over 17,000 outpatients with schizophrenia from 37 countries worldwide. The present post hoc study focused on the subgroup of patients who started taking olanzapine at baseline and subsequently made the first switch to risperidone (n=162) and vice versa (n=136). Clinical status was assessed at the visit when the first switch was made (i.e. before switching) and after switching. Logistic regression models examined the impact of medication switch on tolerability outcomes, and linear regression models assessed the association between medication switch and change in the Clinical Global Impression-Schizophrenia (CGI-SCH) overall score or change in weight. In addition, Kaplan-Meier survival curves and Cox-proportional hazards models were used to analyze the time to medication switch as well as time to relapse (symptom worsening as assessed by the CGI-SCH scale or hospitalization). RESULTS: 48% and 39% of patients switching to olanzapine and risperidone, respectively, remained on the medication without further switches (p=0.019). Patients switching to olanzapine were significantly less likely to experience relapse (hazard ratio: 3.43, 95% CI: 1.43, 8.26), extrapyramidal symptoms (odds ratio [OR]: 4.02, 95% CI: 1.49, 10.89) and amenorrhea/galactorrhea (OR: 8.99, 95% CI: 2.30, 35.13). No significant difference in weight change was, however, found between the two groups. While the CGI-SCH overall score improved in both groups after switching, there was a significantly greater change in those who switched to olanzapine (difference of 0.29 points, p=0.013). CONCLUSION: Our study showed that patients who switched from risperidone to olanzapine were likely to experience a more favorable treatment course than those who switched from olanzapine to risperidone. Given the nature of observational study design and small sample size, additional studies are warranted

Patient characteristics associated with treatment initiation among paediatric patients with Attention-Deficit/Hyperactivity Disorder symptoms in a naturalistic setting in Central Europe and East Asia

BACKGROUND: Cultural views of Attention-Deficit/Hyperactivity Disorder (ADHD), differing healthcare systems and funding mechanisms, and the availability of mental health services can greatly influence the perceptions, diagnosis, and treatment of ADHD. There is, however, lack of information about treatment practice and the treatment decision-making process for ADHD, particularly in non-Western countries. Our study compared characteristics of paediatric patients newly diagnosed with ADHD symptoms who did and who did not initiate treatment, and also examined whether any differences varied by region in Central Europe and East Asia. METHODS: Data were taken from a 1-year prospective, observational study that included 1,068 paediatric patients newly diagnosed with ADHD symptoms. Clinical severity was measured using the Clinical Global Impression-ADHD-Severity (CGI-ADHD-S) scale and the Child Symptom Inventory-4 (CSI-4) checklist. Logistic regression was used to explore patient characteristics associated with treatment initiation (pharmacotherapy and/or psychotherapy) at baseline for each region. RESULTS: A total of 74.3% of patients initiated treatment at baseline (78.3% in Central Europe and 69.9% in East Asia). Of these, 48.8% started with both pharmacotherapy and psychotherapy in Central Europe, and only 17.1% did so in East Asia. The level of clinical severity was highest in the combination treatment group in Central Europe, but was highest in the psychotherapy only group in East Asia. In East Asia, treatment initiation was associated with being older, being male, and having a higher CGI-ADHD-S score. In Central Europe, treatment initiation was associated with parental psychological distress, having a higher CSI-4 score, and not being involved in bullying. CONCLUSIONS: Although factors associated with treatment initiation differed to some extent between Central Europe and East Asia, clinical severity appeared to be one of the most important determinants of treatment initiation in both regions. However, the choice between pharmacotherapy and psychotherapy, either alone or in combination, varied substantially across the regions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12888-014-0304-x) contains supplementary material, which is available to authorized users

Functional impairment and painful physical symptoms in patients with major depressive disorder treated with antidepressants: real-world evidence from the Middle East

BACKGROUND: The Global Burden of Disease 2010 study reported the relative size of major depressive disorder (MDD) burden to be greater in the Middle East and North Africa than anywhere else. However, little research has been carried out to examine the comparative effectiveness of antidepressants in this region. OBJECTIVE: To assess and compare functioning levels in Middle Eastern patients with MDD treated with either duloxetine or a selective serotonin reuptake inhibitor (SSRI), and to examine the impacts of depression-related pain on functioning by the type of treatment. METHOD: This post-hoc analysis, which focused on Middle Eastern patients, used data from a 6-month prospective observational study that included 1,549 MDD patients without sexual dysfunction. Levels of functional impairment and depression-related pain were assessed using the Sheehan Disability Scale (SDS) and the modified Somatic Symptom Inventory, respectively. A mixed model with repeated measures (MMRM) was employed. RESULTS: The mean age of the patients was 37.3 (SD=8.4) years, and 34.6% were female. Patient functioning was, on average, moderately impaired at baseline, but improved substantially during follow-up in both the duloxetine (n=152) and the SSRI (n=123) cohorts. The MMRM results showed a lower level of functional impairment at 24 weeks in the duloxetine cohort than in the SSRI cohort (p<0.001). Pain severity at baseline was positively associated with functional impairment during follow-up only in the SSRI cohort (p=0.003). CONCLUSION: Duloxetine-treated MDD patients achieved better functioning than SSRI-treated patients. This treatment difference was partly driven by depression-related pain

Predictors and consequences of adherence to the treatment of pediatric patients with attention-deficit/hyperactivity disorder in Central Europe and East Asia.

PURPOSE: To assess baseline predictors and consequences of medication non-adherence in the treatment of pediatric patients with attention-deficit/hyperactivity disorder (ADHD) from Central Europe and East Asia. PATIENTS AND METHODS: Data for this post-hoc analysis were taken from a 1-year prospective, observational study that included a total of 1,068 newly-diagnosed pediatric patients with ADHD symptoms from Central Europe and East Asia. Medication adherence during the week prior to each visit was assessed by treating physicians using a 5-point Likert scale, and then dichotomized into either adherent or non-adherent. Clinical severity was measured by the Clinical Global Impressions-ADHD-Severity (CGI-ADHD) scale and the Child Symptom Inventory-4 (CSI-4) Checklist. Health-Related Quality of Life (HRQoL) was measured using the Child Health and Illness Profile-Child Edition (CHIP-CE). Regression analyses were used to assess baseline predictors of overall adherence during follow-up, and the impact of time-varying adherence on subsequent outcomes: response (defined as a decrease of at least 1 point in CGI), changes in CGI-ADHD, CSI-4, and the five dimensions of CHIP-CE. RESULTS: Of the 860 patients analyzed, 64.5% (71.6% in Central Europe and 55.5% in East Asia) were rated as adherent and 35.5% as non-adherent during follow-up. Being from East Asia was found to be a strong predictor of non-adherence. In East Asia, a family history of ADHD and parental emotional distress were associated with non-adherence, while having no other children living at home was associated with non-adherence in Central Europe as well as in the overall sample. Non-adherence was associated with poorer response and less improvement on CGI-ADHD and CSI-4, but not on CHIP-CE. CONCLUSION: Non-adherence to medication is common in the treatment of ADHD, particularly in East Asia. Non-adherence was associated with poorer response and less improvement in clinical severity. A limitation of this study is that medication adherence was assessed by the treating clinician using a single item question

Patient characteristics associated with treatment initiation among paediatric patients with Attention-Deficit/Hyperactivity Disorder symptoms in a naturalistic setting in Central Europe and East Asia.

BACKGROUND: Cultural views of Attention-Deficit/Hyperactivity Disorder (ADHD), differing healthcare systems and funding mechanisms, and the availability of mental health services can greatly influence the perceptions, diagnosis, and treatment of ADHD. There is, however, lack of information about treatment practice and the treatment decision-making process for ADHD, particularly in non-Western countries. Our study compared characteristics of paediatric patients newly diagnosed with ADHD symptoms who did and who did not initiate treatment, and also examined whether any differences varied by region in Central Europe and East Asia. METHODS: Data were taken from a 1-year prospective, observational study that included 1,068 paediatric patients newly diagnosed with ADHD symptoms. Clinical severity was measured using the Clinical Global Impression-ADHD-Severity (CGI-ADHD-S) scale and the Child Symptom Inventory-4 (CSI-4) checklist. Logistic regression was used to explore patient characteristics associated with treatment initiation (pharmacotherapy and/or psychotherapy) at baseline for each region. RESULTS: A total of 74.3% of patients initiated treatment at baseline (78.3% in Central Europe and 69.9% in East Asia). Of these, 48.8% started with both pharmacotherapy and psychotherapy in Central Europe, and only 17.1% did so in East Asia. The level of clinical severity was highest in the combination treatment group in Central Europe, but was highest in the psychotherapy only group in East Asia. In East Asia, treatment initiation was associated with being older, being male, and having a higher CGI-ADHD-S score. In Central Europe, treatment initiation was associated with parental psychological distress, having a higher CSI-4 score, and not being involved in bullying. CONCLUSIONS: Although factors associated with treatment initiation differed to some extent between Central Europe and East Asia, clinical severity appeared to be one of the most important determinants of treatment initiation in both regions. However, the choice between pharmacotherapy and psychotherapy, either alone or in combination, varied substantially across the regions

Functioning in patients with major depression treated with duloxetine or a selective serotonin reuptake inhibitor in East Asia

PURPOSE: To assess and compare the levels of functioning in patients with major depressive disorder treated with either duloxetine with a daily dose of ≤60 mg or a selective serotonin reuptake inhibitor (SSRI) as monotherapy for up to 6 months in a naturalistic setting in East Asia. In addition, this study examined the impact of painful physical symptoms (PPS) on the effects of these treatments. PATIENTS AND METHODS: Data for this post hoc analysis were taken from a 6-month prospective observational study involving 1,549 patients with major depressive disorder without sexual dysfunction. The present analysis focused on a subgroup of patients from East Asia (n=587). Functioning was measured using the Sheehan Disability Scale (SDS). Depression severity was assessed using the 16-item Quick Inventory of Depressive Symptomatology-Self Report. PPS were rated using the modified Somatic Symptom Inventory. A mixed model with repeated measures was fitted to compare the levels of functioning between duloxetine-treated (n=227) and SSRI-treated (n=225) patients, adjusting for baseline patient characteristics. RESULTS: The mean SDS total score was similar between the two treatment cohorts (15.46 [standard deviation =6.11] in the duloxetine cohort and 16.36 [standard deviation =6.53] in the SSRI cohort, P=0.077) at baseline. Both descriptive and regression analyses confirmed improvement in functioning in both groups during follow-up, but duloxetine-treated patients achieved better functioning. At 24 weeks, the estimated mean SDS total score was 4.48 (standard error =0.80) in the duloxetine cohort, which was statistically significantly lower (ie, better functioning) than that of 6.76 (standard error =0.77) in the SSRI cohort (P<0.001). This treatment difference was more apparent in the subgroup of patients with PPS at baseline. Similar patterns were also observed for SDS subscores (work, social life, and family life). CONCLUSION: Depressed patients treated with duloxetine achieved better functioning compared to those treated with SSRIs. This treatment difference was mostly driven by patients with PPS at baseline

Should Unexplained Painful Physical Symptoms be Considered within the Spectrum of Depressive Symptoms?

OBJECTIVE: To examine whether painful physical symptoms (PPS) can be considered within the spectrum of depressive symptoms. METHODS: Data for this post-hoc analysis were taken from a 6-month observational study mostly conducted in East Asia, Mexico, and the Middle East of 1,549 depressed patients without sexual dysfunction at baseline. Both explanatory and confirmatory factor analyses (EFA and CFA) were performed on the combined items of the 16-item Quick Inventory of Depressive Symptomatology Self-Report and the Somatic Symptom Inventory (seven pain-related items only). An additional second-order CFA was also conducted to examine an association between retained factors and the overall 'depressive symptoms' factor. In addition, Spearman's correlation was used to assess levels of correlation between retained factors and depression severity as well as quality of life. RESULTS: Both EFA and CFA suggested and validated a four-factor solution, which included a pain factor. The other three factors identified were a mood/cognitive factor, a sleep disturbance factor, and an appetite/weight disturbance factor. All four factors were significantly associated with the overall factor of depression. They were also highly correlated to depression severity and quality of life (p<0.001 for all). The levels of correlations with the pain factor were generally greater than those with the appetite/weight factor and similar to those with the sleep factor. CONCLUSION: It may be reasonable to consider PPS within a broad spectrum of depressive symptoms. At least, they should be routinely assessed in patients with depression. Further research is warranted to validate these preliminary findings