The relationship of subjective social status to mental health in South Korean adults

Abstract

South Korea has witnessed an unprecedented rise in suicide rates following the 1997 Asian financial crisis. Unfortunately, the rate has not decreased and still remains the highest among the 34 countries which are part of the Organization for Economic Co-operation and Development (OECD). Several researchers have suggested that, in high-income countries, it is no longer the absolute level of one’s socioeconomic status (SES) that is most important for health, but rather inequality or a sense of inequality. A number of studies have been undertaken to examine the relationship of inequality (at the country level) or a sense of inequality (at the individual level) to health. Some of these studies have focused on subjective SES, which measures one’s perception of his/her own position in the social hierarchy. We aimed to examine how both objective and subjective SES are related to mental health problems (suicidal ideation, depressive symptoms and psychological distress) in South Korea, using data from the 2013 Korea Health Panel survey. Subjective SES was measured using the MacArthur scale, a 10rung ladder on which individuals indicate their perceived standing in the social hierarchy. The assessment of suicidal ideation and depression was based on self-report (“yes” versus “no” in the past 12 months). Psychological distress in the past month was assessed using the Korean version of the Brief Encounter Psychosocial Instrument (BEPSI-K). A score 2.4 was defined as “severe stress”. Of the 16,313 respondents aged 19 years or older, the 14,432 who had no missing data were included in this analysis. All data were weighted to represent the structure of the Korean population. Of the 14,432 participants, 5.4% and 7.2% had suicidal ideation and depression, respectively, in the past 12 months, and 13.6% had severe psychological distress in the past month. A clear social gradient was found in the prevalence of these mental health problems, especially when SES was measured subjectively (subjective SES) rather than objectively (income quintile) (p<0.001). Notably, this pattern was more apparent in the case of severe psychological distress. Of those with the lowest subjective SES (i.e., a rating of 1 on the 10-rung ladder), nearly one in three (29.6%) reported the experience of severe psychological distress in the past month, while only 7.2% reported the same experience among those with the highest subjective SES (i.e., a rating 5). The equivalent rates were 19.3% in the lowest income quintile and 10.2% in the highest income quintile. The associations with subjective SES appeared to far outweigh those with conventional measures of SES when considering both in logistic regression models. Subjective SES was the only factor that was consistently associated with any type of mental health problems. For instance, compared to the respondents with the lowest subjective SES (i.e., a rating of 1 on the 10-rung ladder), those with higher subjective SES were much less likely to report suicidal ideation (OR50.60 in the group with a rating of 2, OR50.40 in those with a rating of 3, OR50.24 in those with a rating of 4, and OR50.20 in respondents with a rating 5; p<0.001 for all). The same applied to depression (OR50.50, 0.38, 0.26, and 0.20; p<0.001 for all), and severe psychological distress (OR50.52, 0.32, 0.25, and 0.19; p<0.001 for all). Associations with objective SES measures (education, employment status, income quintiles) were infrequently observed. Previous studies have shown that the strength of the association between subjective SES and health varies across countries. Contextual factors such as social structure and culture are likely to strengthen or weaken the association between the two. What factors might then have strengthened the relationship between subjective SES and mental health in South Korea? This country achieved rapid economic growth while maintaining a relatively equitable income distribution up until the mid-1990s. However, it fell into a severe recession following the 1997 Asian financial crisis, which in turn served as a major turning point in the Korean society. Massive structural reforms were undertaken to promote economic productivity and globalization. These reforms have had a significant impact on the labour market, increasing labour flexibility and job insecurity. As a result, the labor market has become highly segmented between regular and non-regular workers. Income inequality has also worsened since the 1997 crisis, despite the resurgence of economic growth (the average gross domestic product increased by 5.4% between 1999 and 2010). The average Gini coefficient, a measure of income inequality, was 0.258 in the period 1990-1995, but increased to 0.298 in 1999 and peaked at 0.320 in 2009. Concomitant to these social changes, a limited number of studies have demonstrated a worsening trend of SES-related inequalities in health. For example, our study published in this journal in 2011 showed a widening income-related inequality in the prevalence of depression and suicidal behaviour over the 1998-2007 period. Nevertheless, our current finding of a strong