Indoor Radon and Lung Cancer: Estimation of Attributable Risk, Disease Burden, and Effects of Mitigation.

PURPOSE: Exposure to indoor radon is associated with lung cancer. This study aimed to estimate the number of lung cancer deaths attributable to indoor radon exposure, its burden of disease, and the effects of radon mitigation in Korea in 2010. MATERIALS AND METHODS: Lung cancer deaths due to indoor radon exposure were estimated using exposure-response relations reported in previous studies. Years of life lost (YLLs) were calculated to quantify disease burden in relation to premature deaths. Mitigation effects were examined under scenarios in which all homes with indoor radon concentrations above a specified level were remediated below the level. RESULTS: The estimated number of lung cancer deaths attributable to indoor radon exposure ranged from 1946 to 3863, accounting for 12.5-24.7% of 15623 total lung cancer deaths in 2010. YLLs due to premature deaths were estimated at 43140-101855 years (90-212 years per 100000 population). If all homes with radon levels above 148 Bq/m³ are effectively remediated, 502-732 lung cancer deaths and 10972-18479 YLLs could be prevented. CONCLUSION: These findings suggest that indoor radon exposure contributes considerably to lung cancer, and that reducing indoor radon concentration would be helpful for decreasing the disease burden from lung cancer deaths.

Dependency on Smartphone Use and Its Association with Anxiety in Korea.

OBJECTIVE: South Korea has the highest rate of smartphone ownership worldwide, which is a potential concern given that smartphone dependency may have deleterious effects on health. We investigated the relationship between smartphone dependency and anxiety. METHODS: Participants included 1,236 smartphone-using students (725 men and 511 women) from six universities in Suwon, South Korea. Participants completed measures of smartphone use, smartphone dependency, anxiety, and general characteristics (i.e., demographic, health-related, and socioeconomic characteristics). To measure smartphone dependency and anxiety, we used questionnaires of Yang's test developed from Young's Internet Addiction Test and Zung's Self-Rating Anxiety Scale. We used multiple logistic regression to determine the association between smartphone dependency and anxiety after adjusting for relevant factors. RESULTS: On a scale from 25 to 100, with higher scores on the smartphone dependency test indicating greater dependency, women were significantly more dependent on smartphones than were men (mean smartphone dependency score: 50.7 vs. 56.0 for men and women, respectively, p<0.001). However, the amount of time spent using smartphones and the purpose of smartphone use affected smartphone dependency in both men and women. Particularly, when daily use time increased, smartphone dependency showed an increasing trend. Compared with times of use <2 hours vs. ≥6 hours, men scored 46.2 and 56.0 on the smartphone dependency test, while women scored 48.0 and 60.4, respectively (p<0.001). Finally, for both men and women, increases in smartphone dependency were associated with increased anxiety scores. With each one-point increase in smartphone dependency score, the risk of abnormal anxiety in men and women increased by 10.1% and 9.2%, respectively (p<0.001). CONCLUSION: Among this group of university students in South Korea, smartphone dependency appeared to be associated with increased anxiety. Standards for smartphone use might help prevent deleterious health effects.

MRI-defined versus clinically-defined vascular depression; comparison of prediction of functional disability in the elderly.

BACKGROUND: We compared the validity of models of subcortical ischemic depression (SID) and depression-executive dysfunction syndrome (DED) in predicting functional disability in the elderly. METHODS: We obtained data from elderly Korean subjects (n=1356) aged 60 years or older at baseline from the CREDOS study from November 2005 to July 2014. A generalized estimating equation (GEE) model was constructed to measure functional disability using instrumental activity of daily living as a primary outcome. A risk factor of interest was SID and DED evaluated by a visual rating scale of deep white matter hyperintensity in MRI, Stroop test and Geriatric Depression Scale (GDS) score. Receiver-operating-characteristic plots and area under the curve (AUC) test were applied to examine the difference of the two definitions of vascular depression with predicted values of functional disability outcome. RESULTS: The mean (SD) follow-up duration of the participants was 1.7 (0.9) years. The GEE model showed that presence of SID at baseline predicted functional disability compared to non-depressed subjects (GDS score: Odds ratio [OR] 1.76; 95% CI 1.23, 2.53; p=0.002). The association was also statistically significant among the DED group (OR 1.48; 95% CI 1.15, 1.92; p=0.003). There were no significant differences in predicting functional disability (95% CI: -0.003 to 0.009, p=0.366) according to AUC differences between SID and DED. CONCLUSIONS: The results will be useful in evaluating the cardinal features of the vascular depression hypothesis in predicting functional disability.

Attributable risk of lung cancer deaths due to indoor radon exposure.

Exposure to radon gas is the second most common cause of lung cancer after smoking. A large number of studies have reported that exposure to indoor radon, even at low concentrations, is associated with lung cancer in the general population. This paper reviewed studies from several countries to assess the attributable risk (AR) of lung cancer death due to indoor radon exposure and the effect of radon mitigation thereon. Worldwide, 3-20 % of all lung cancer deaths are likely caused by indoor radon exposure. These values tend to be higher in countries reporting high radon concentrations, which can depend on the estimation method. The estimated number of lung cancer deaths due to radon exposure in several countries varied from 150 to 40,477 annually. In general, the percent ARs were higher among never-smokers than among ever-smokers, whereas much more lung cancer deaths attributable to radon occurred among ever-smokers because of the higher rate of lung cancers among smokers. Regardless of smoking status, the proportion of lung cancer deaths induced by radon was slightly higher among females than males. However, after stratifying populations according to smoking status, the percent ARs were similar between genders. If all homes with radon above 100 Bq/m(3) were effectively remediated, studies in Germany and Canada found that 302 and 1704 lung cancer deaths could be prevented each year, respectively. These estimates, however, are subject to varying degrees of uncertainty related to the weakness of the models used and a number of factors influencing indoor radon concentrations.

Regional differences in vitamin D levels and incidence of food-induced anaphylaxis in South Korea.

BACKGROUND: Previous studies have suggested low vitamin D as a potential risk factor for food allergy/anaphylaxis. However, few studies have investigated the association between vitamin D and food-induced anaphylaxis (FIA) in South Korea. OBJECTIVE: To examine regional differences in serum vitamin D levels and FIA incidence. METHODS: We used nationwide data collected from 2011 to 2013. Data on vitamin D were obtained from the Korea National Health and Nutrition Examination Survey; data on FIA were obtained from the Health Insurance and Assessment Service. Districts were grouped into region 1 (lower solar radiation) and region 2 (higher solar radiation). We examined differences in FIA incidence and vitamin D levels between the regions, adjusting for age. RESULTS: The study included 2,814 patients with FIA and 15,367 people with available serum vitamin D measurements. Age-adjusted FIA incidence was 2.2 per 100,000 person-years in region 1 and 1.8 per 100,000 person-years in region 2 (relative risk, 1.23; 95% confidence interval, 1.09-1.39). Age-adjusted serum vitamin D levels were 16.5 ng/mL in region 1 and 17.8 ng/mL in region 2 (mean difference, 1.3 ng/mL; 95% confidence interval, 0.9-1.9). After stratification by age, sex, and area of residence, region 1 still had higher FIA incidence and lower vitamin D levels than region 2. CONCLUSION: The present study found a higher incidence of FIA in regions with lower vitamin D levels in the population. Further investigation is necessary to identify any direct associations between vitamin D and food allergy/anaphylaxis.

Differential effects of white matter hyperintensity on geriatric depressive symptoms according to APOE-ε4 status.

BACKGROUND: We aimed to examine differential effects of WMH on progression of depressive symptoms according to APOE ε4 status in the elderly. METHODS: We obtained data from elderly Korean subjects (n=707) aged 60 years or older at baseline from the CREDOS study from November 2005 to July 2014. A linear mixed model stratified according to APOE genotype (APOE ε4 carrier vs. non-carrier) was constructed using GDS score as a primary outcome and degree of overall, deep, periventricular WMH evaluated by a visual rating scale as a risk factor of interest. We also tested interaction between APOE ε4, WMH and time as predictors of clinical progression on GDS scores to examine the moderating effect of APOE ε4 allele on the relationship between degree of WMH and progression of geriatric depressive symptoms. RESULTS: The mean (SD) follow-up duration of the participants was 2.0 (0.8) years. Among APOE ε4 carriers, a severe degree of overall and deep WMH, but not periventricular WMH, predicted progression of geriatric depressive symptoms (overall WMH: coefficient=0.96, p=0.010; deep WMH: 0.87, p=0.016). There were significant interaction between APOE ε4, degree of WMH and time in predicting GDS increase (5df, F=2.28, p=0.046). LIMITATIONS: Only subjects seeking medical attention and with follow-up measurements were enrolled in this study. Specific location of WMH and use of antidepressant were uncontrolled. CONCLUSIONS: Considering biological markers such as degree of WMH and APOE ε4 status may be clinically relevant to predicting progression of geriatric depressive symptoms.

Psychological Distress in Young Adult Males with Atopic Dermatitis: A Cross-Sectional Study.

The relationship between atopic dermatitis (AD) and psychological distress has been well established for children and adolescents. However, it is unclear whether this relationship exists in young adults. This study aimed to assess the relationship between AD and psychological distress in young male adults in South Korea. A cross-sectional study was conducted using regional conscription data from 2008 to 2012. A dermatologist diagnosed AD based on historical and clinical features, and determined severity using the eczema area and severity index. A psychiatrist used medical records, an interview, and a psychological test to examine psychological distress (depression, anxiety, and somatization). The relationship between psychological distress and AD was assessed by multivariate logistic regression analyses. Among the 120,508 conscripts, 1517 (1.2%) presented with AD. The odds of having each type of psychological distress were significantly greater for individuals with AD compared with those without AD. The adjusted odds ratios for depression, anxiety, and somatization were 1.79 (95% CI 1.40-2.29), 1.38 (95% CI 1.08-1.76), and 1.75 (95% CI 1.40-2.20), respectively. Moderate-to-severe AD was significantly related to depression and somatization to a greater extent compared with mild AD. Depression, anxiety, and somatization are strongly and independently associated with AD in young adult males. Early treatment of skin inflammation might modify the risk of psychiatric problems. Prospective cohort studies are needed to verify causal relationships.

The effect of pre-existing medical conditions on heat stroke during hot weather in South Korea.

BACKGROUND: Heat stroke contributes considerably to morbidity and mortality in hot weather, but it is unclear whether pre-existing medical conditions increase the risk of heat stroke. The purpose of this study was to assess the association between heat stroke and pre-existing medical conditions in South Korea. METHODS: A case-control study was conducted using data from a nationwide surveillance system for heat illnesses in 2012. Individuals with heat stroke were identified and compared to control subjects with mild heat illness such as heat exhaustion, heat edema, heat cramps, and heat syncope. Categories of pre-existing medical conditions included cardio/cerebrovascular disease, respiratory disease, neuropsychiatric disorder, and diabetes mellitus. Associations between heat stroke and pre-existing medical conditions were assessed by multivariate logistic regression analyses. RESULTS: Of 968 eligible patients, 178 (18.4%) presented with heat stroke. Patients with pre-existing medical conditions were relatively greater in the heat stroke group than in the control group (40.4% and 23.9%, respectively). Neuropsychiatric disorder was associated with an increased odds of heat stroke after adjustment for covariates (adjusted odds ratio, 7.69; 95% CI, 4.06-14.54). There were no significant relationships between heat stroke and other medical conditions (cardio/cerebrovascular disease: 0.66, 0.40-1.06; respiratory disease: 1.44, 0.35-5.89; diabetes mellitus: 1.16, 0.58-2.34). CONCLUSIONS: Pre-existing neuropsychiatric disorder was associated with an increased risk of heat stroke. National strategies and clinical guidance for such patients should be initiated to prevent fatal events.

The Long and Short Incubation Periods of Plasmodium vivax Malaria in Korea: The Characteristics and Relating Factors.

BACKGROUND: The cases of Plasmodium vivax malaria in Korea are mixed with long and short incubation periods. This study aims to define clinico-epidemiologic chracteristcs of Plasmodium vivax malaria in Korea. MATERIALS AND METHODS: We selected the civilian cases infected with P. vivax malaria in Korea from the epidemiological investigation data of 2001 to 2010, whose incubation periods could be estimated. The long and short incubation periods were defined by duration of infection and onset time, and the cases were compared by demographic factors and clinical symptom, infection and onset time. The correlation was analyzed between the proportion of cases in the infected region with the long incubation period and meteorological factors along with latitude. RESULTS: The length of the mean short and long incubation periods for the cases were 25.5 days and 329.4 days, respectively. The total number of the study subjects was 897, and the number cases of short and long incubation periods was 575 (64.1%) and 322 (35.9%), respectively. The aspect of incubation period showed a significant difference by region of infection; there was a higher proportion of long incubation period infection cases in Gangwon-do than in Gyeonggi-do and Incheon. The proportion of long incubation period cases showed significant correlation with latitude and temperature of August and September of the infected regions. CONCLUSIONS: Incubation period of P. vivax malaria in Korea showed significant difference by infected region, infection and onset time and the proportion of long incubation period cases showed significant correlation with latitude and meteorological factors of the infected regions.

Impact of meteorological variation on hospital visits of patients with tree pollen allergy.

BACKGROUND: Climate change could affect allergic diseases, especially due to pollen. However, there has been no epidemiologic study to demonstrate the relationship between meteorological factors, pollen, and allergic patients. We aimed to investigate the association between meteorological variations and hospital visits of patients with tree pollen allergy. METHODS: The study subjects were adult patients who received skin prick tests between April and July from 1999 to 2008. We reviewed the medical records for the test results of 4,715 patients. Patients with tree pollen allergy were defined as those sensitized to more than 1 of 12 tree pollen allergens. We used monthly means of airborne tree pollen counts and meteorological factors: maximum/average/minimum temperature, relative humidity, and precipitation. We analyzed the correlations between meteorological variations, tree pollen counts, and the patient numbers. Multivariable logistic regression analyses were used to investigate the associations between meteorological factors and hospital visits of patients. RESULTS: The minimum temperature in March was significantly and positively correlated with tree pollen counts in March/April and patient numbers from April through July. Pollen counts in March/April were also correlated with patient numbers from April through July. After adjusting for confounders, including air pollutants, there was a positive association between the minimum temperature in March and hospital visits of patients with tree pollen allergy from April to July(odds ratio, 1.14; 95% CI 1.03 to 1.25). CONCLUSIONS: Higher temperatures could increase tree pollen counts, affecting the symptoms of patients with tree pollen allergy, thereby increasing the number of patients visiting hospitals.

[Correlations between climate change-related infectious diseases and meteorological factors in Korea].

OBJECTIVES: Infectious diseases are known to be affected by climate change. We investigated if the infectious diseases were related to meteorological factors in Korea. METHODS: Scrub typhus, hemorrhagic fever with renal syndrome (HFRS), leptospirosis, malaria and Vibrio vulnificus sepsis among the National Notifiable Infectious Diseases were selected as the climate change-related infectious diseases. Temperature, relative humidity and precipitation were used as meteorological factors. The study period was from 2001 through 2008. We examined the seasonality of the diseases and those correlations with meteorological factors. We also analyzed the correlations between the incidences of the diseases during the outbreak periods and monthly meteorological factors in the hyper-endemic regions. RESULTS: All of the investigated diseases showed strong seasonality; malaria and V. vulnificus sepsis were prevalent in summer and scrub typhus, HFRS and leptospirosis were prevalent in the autumn. There were significant correlations between the monthly numbers of cases and all the meteorological factors for malaria and V. vulnificus sepsis, but there were no correlation for the other diseases. However, the incidence of scrub typhus in hyper-endemic region during the outbreak period was positively correlated with temperature and humidity during the summer. The incidences of HFRS and leptospirosis had positive correlations with precipitation in November and temperature and humidity in February, respectively. V. vulnificus sepsis showed positive correlations with precipitation in April/May/July. CONCLUSIONS: In Korea, the incidences of the infectious diseases were correlated with meteorological factors, and this implies that the incidences could be influenced by climate change.

Systematic review of health behavioral risks and cognitive health in older adults.

BACKGROUND: An increasing body of evidence suggests that health behaviors may protect against cognitive impairment and dementia. The purpose of this study was to summarize the current evidence on health behavioral factors predicting cognitive health through a systematic review of the published literature. METHODS: PubMed, Embase, and PsycINFO databases were searched for studies on community representative samples aged 65 and older, with prospective cohort design and multivariate analysis. The outcome--cognitive health--was defined as a continuum of cognitive function ranging from cognitive decline to impairment and dementia, and health behaviors included physical activity, smoking, alcohol drinking, body mass index, and diet and nutrition. RESULTS: Of 12,105 abstracts identified, 690 relevant full-texts were reviewed. The final yield amounted to 115 articles of which 37 studies were chosen that met the highest standards of quality. Leisure time physical activity, even of moderate level, showed protective effects against dementia, whereas smoking elevated the risk of Alzheimer's disease. Moderate alcohol consumption tended to be protective against cognitive decline and dementia, but nondrinkers and frequent drinkers exhibited a higher risk for dementia and cognitive impairment. Midlife obesity had an adverse effect on cognitive function in later life. Analysis showed vegetable and fish consumption to be of benefit, whereas, persons consuming a diet high in saturated fat had an increased dementia risk. CONCLUSION: The review demonstrates accumulating evidence supporting health behavioral effects in reducing the risk of cognitive decline and dementia. Results indicate potential benefits of healthy lifestyles in protecting cognitive health in later life.