Air pollution and unintentional injury deaths in South Korea

This study aimed to assess the association between exposure to air pollution and unintentional injury deaths in South Korea. Data regarding all unintentional injury deaths (17,566) in seven metropolitan cities from 2002 to 2008 were collected. Using a time-stratified case-crossover study, conditional logistic regression and subgroup analyses were performed after stratification by age, gender, and season. To evaluate immediate and delayed effects of air pollutants, we used both single lag and distributed lag models. The risk was expressed as an odds ratio (OR) per one interquartile range (IQR) of each air pollutant. During the study period, the median (IQR) levels of air pollutants were 0.005 (0.004-0.007) ppm for sulfur dioxide (SO₂), 0.02 (0.02-0.03) ppm for nitrogen dioxide (NO₂), 0.03 (0.02-0.04) ppm for ozone (O₃), 48.3 (34.9-67.0) μg/m(3) for particulate matter ≤10 μm in aerodynamic diameter (PM₁₀), and 0.36 (0.1-0.6) ppm for carbon monoxide (CO). All air pollutants, with the exception of PM₁₀ and O₃, were significantly associated with an increased risk of unintentional injury deaths; the maximum risk was observed in the distributed lag 1 model for SO₂ (OR, 1.119; 95% confidence interval, 1.022-1.226), NO₂ (1.208; 1.043-1.400), and CO (1.012; 1.000-1.024). After stratification of the subjects by age, SO₂, NO₂, and CO were significantly associated with increased risk of unintentional injury deaths among subjects aged 60 years or older in the distributed lag 1 model, while O₃ and PM₁₀ were associated with increased risk among subjects aged 40 to 59 years. However, in subjects younger than 40 years of age, we found no significant associations for any of the air pollutants. Our study suggested evidence for a short-term association between air pollutants and unintentional injury deaths, even at low pollutants levels.

Pathway analysis of genome-wide association datasets of personality traits

Although several genome-wide association (GWA) studies of human personality have been recently published, genetic variants that are highly associated with certain personality traits remain unknown, due to difficulty reproducing results. To further investigate these genetic variants, we assessed biological pathways using GWA datasets. Pathway analysis using GWA data was performed on 1089 Korean women whose personality traits were measured with the Revised NEO Personality Inventory for the 5-factor model of personality. A total of 1042 pathways containing 8297 genes were included in our study. Of these, 14 pathways were highly enriched with association signals that were validated in 1490 independent samples. These pathways include association of: Neuroticism with axon guidance [L1 cell adhesion molecule (L1CAM) interactions]; Extraversion with neuronal system and voltage-gated potassium channels; Agreeableness with L1CAM interaction, neurotransmitter receptor binding and downstream transmission in postsynaptic cells; and Conscientiousness with the interferon-gamma and platelet-derived growth factor receptor beta polypeptide pathways. Several genes that contribute to top-ranked pathways in this study were previously identified in GWA studies or by pathway analysis in schizophrenia or other neuropsychiatric disorders. Here we report the first pathway analysis of all five personality traits. Importantly, our analysis identified novel pathways that contribute to understanding the etiology of personality traits.

Ambient ozone concentration and emergency department visits for panic attacks

The effect of ambient air pollution on panic disorder in the general population has not yet been thoroughly elucidated, although the occurrence of panic disorder in workers exposed to organic solvents has been reported previously. We investigated the association of ambient air pollution with the risk of panic attack-related emergency department visits. Using health insurance claims, we collected data from emergency department visits for panic attacks in Seoul, Republic of Korea (2005-2009). Daily air pollutant concentrations were obtained using automatic monitoring system data. We conducted a time-series study using a generalized additive model with Poisson distribution, which included spline variables (date of visit, daily mean temperature, and relative humidity) and parametric variables (daily mean air pollutant concentration, national holiday, and day of the week). In addition to single lag models (lag1 to lag3), cumulative lag models (lag0-1 to lag0-3) were constructed using moving-average concentrations on the days leading up to the visit. The risk was expressed as relative risk (RR) per one standard deviation of each air pollutant and its 95% confidence interval (95% CI). A total of 2320 emergency department visits for panic attacks were observed during the study period. The adjusted RR of panic attack-related emergency department visits was 1.051 (95% CI, 1.014-1.090) for same-day exposure to ozone. In cumulative models, adjusted RRs were 1.068 (1.029-1.107) in lag0-2 and 1.074 (1.035-1.114) in lag0-3. The ambient ozone concentration was significantly associated with emergency department visits for panic attacks.

Medical care expenditure in suicides from non-illness-related causes

OBJECTIVES

Several epidemiological studies on medical care utilization prior to suicide have considered the motivation of suicide, but focused on the influence of physical illnesses. Medical care expenditure in suicide completers with non-illness-related causes has not been investigated.

METHODS

Suicides motivated by non-illness-related factors were identified using the investigator's note from the National Police Agency, which was then linked to the Health Insurance Review and Assessment data. We investigated the medical care expenditures of cases one year prior to committing suicide and conducted a case-control study using conditional logistic regression analysis after adjusting for age, gender, area of residence, and socioeconomic status.

RESULTS

Among the 4515 suicides motivated by non-illness-related causes, medical care expenditures increased in only the last 3 months prior to suicide in the adolescent group. In the younger group, the proportion of total medical expenditure for external injuries was higher than that in the older groups. Conditional logistic regression analysis showed significant associations with being a suicide completer and having a rural residence, low socioeconomic status, and high medical care expenditure. After stratification into the four age groups, a significant positive association with medical care expenditures and being a suicide completer was found in the adolescent and young adult groups, but no significant results were found in the elderly groups for both men and women.

CONCLUSIONS

Younger adults who committed suicide motivated by non-illness-related causes had a higher proportion of external injuries and more medical care expenditures than their controls did. This reinforces the notion that suicide prevention strategies for young people with suicidal risk factors are needed.