Dae Ryong Kang

Participation in Physical, Social, and Religious Activity and Risk of Depression in the Elderly: A Community-Based Three-Year Longitudinal Study in Korea

Background We examined the longitudinal association between participation in individual or combinations of physical, social, and religious activity and risk of depression in the elderly. Methods Elderly subjects aged ≥60 years who completed the Living Profiles of Older People Survey in Korea (n = 6,647) were included. The baseline assessment, Wave 1, was conducted in 2008, and a follow-up assessment, Wave 2, was conducted in 2011. We defined participation in frequent physical activity as ≥3 times weekly (at least 30 minutes per activity). Frequent participation in social and religious activity was defined as ≥1 activity weekly. The primary outcome was depression at 3-year follow up. Results Multivariable logistic regression analysis showed that subjects who participated in frequent physical, social, and religious activity had an adjusted odds ratio of 0.81 (95% confidence interval [CI], 0.69–0.96), 0.87 (95% CI, 0.75–1.00), and 0.78 (95% CI, 0.67–0.90), respectively, compared with participants who did not participate in each activity. Participants who participated in only one type of activity frequently and participants who participated in two or three types of activities frequently had an adjusted odds ratio of 0.86 (95% CI, 0.75–0.98) and 0.64 (95% CI, 0.52–0.79), respectively, compared with participants who did not participate in any type of physical, social, and religious activity frequently. Conclusion Participation in physical, social, and religious activity was associated with decreased risk of depression in the elderly. In addition, risk of depression was much lower in the elderly people who participated in two or three of the above-mentioned types of activity than that in the elderly who did not.

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, 3–20xa0% 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 100xa0Bq/m3 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.

An updated review of case-control studies of lung cancer and indoor radon-Is indoor radon the risk factor for lung cancer?

Lung cancer is a leading cause of cancer-related death in the world. Smoking is definitely the most important risk factor for lung cancer. Radon (222Rn) is a natural gas produced from radium (226Ra) in the decay series of uranium (238U). Radon exposure is the second most common cause of lung cancer and the first risk factor for lung cancer in never-smokers.Case–control studies have provided epidemiological evidence of the causative relationship between indoor radon exposure and lung cancer. Twenty-four case–control study papers were found by our search strategy from the PubMed database. Among them, seven studies showed that indoor radon has a statistically significant association with lung cancer. The studies performed in radon-prone areas showed a more positive association between radon and lung cancer. Reviewed papers had inconsistent results on the dose–response relationship between indoor radon and lung cancer risk.Further refined case–control studies will be required to evaluate the relationship between radon and lung cancer. Sufficient study sample size, proper interview methods, valid and precise indoor radon measurement, wide range of indoor radon, and appropriate control of confounders such as smoking status should be considered in further case–control studies.

Development and Validation of Osteoporosis Risk-Assessment Model for Korean Men.

Purpose The aim of the present study was to develop an osteoporosis risk-assessment model to identify high-risk individuals among Korean men. Materials and Methods The study used data from 1340 and 1110 men ≥50 years who participated in the 2009 and 2010 Korean National Health and Nutrition Examination Survey, respectively, for development and validation of an osteoporosis risk-assessment model. Osteoporosis was defined as T score ≤-2.5 at either the femoral neck or lumbar spine. Performance of the candidate models and the Osteoporosis Self-assessment Tool for Asian (OSTA) was compared with sensitivity, specificity, and area under the receiver operating characteristics curve (AUC). A net reclassification improvement was further calculated to compare the developed Korean Osteoporosis Risk-Assessment Model for Men (KORAM-M) with OSTA. Results In the development dataset, the prevalence of osteoporosis was 8.1%. KORAM-M, consisting of age and body weight, had a sensitivity of 90.8%, a specificity of 42.4%, and an AUC of 0.666 with a cut-off score of -9. In the validation dataset, similar results were shown: sensitivity 87.9%, specificity 39.7%, and AUC 0.638. Additionally, risk categorization with KORAM-M showed improved reclassification over that of OSTA up to 22.8%. Conclusion KORAM-M can be simply used as a pre-screening tool to identify candidates for dual energy X-ray absorptiometry tests.

Gene mutation discovery research of non-smoking lung cancer patients due to indoor radon exposure.

Although the incidence and mortality for most cancers such as lung and colon are decreasing in several countries, they are increasing in several developed countries because of an unhealthy western lifestyles including smoking, physical inactivity and consumption of calorie-dense food. The incidences for lung and colon cancers in a few of these countries have already exceeded those in the United States and other western countries. Among them, lung cancer is the main cause of cancer death in worldwide. The cumulative survival rate at five years differs between 13 and 21xa0% in several countries. Although the most important risk factors are smoking for lung cancer, however, the increased incidence of lung cancer in never smokers(LCINS) is necessary to improve knowledge concerning other risk factors. Environmental factors and genetic susceptibility are also thought to contribute to lung cancer risk. Patients with lung adenocarcinoma who have never smoking frequently contain mutation within tyrosine kinase domain of the epidermal growth factor receptor(EGFR) gene. Also, K-ras mutations are more common in individuals with a history of smoking use and are related with resistance to EFGR-tyrosine kinase inhibitors. Recently, radon(Rn), natural and noble gas, has been recognized as second common reason of lung cancer. In this review, we aim to know whether residential radon is associated with an increased risk for developing lung cancer and regulated by several genetic polymorphisms.

Underweight and mortality

OBJECTIVEnAccording to most prospective studies, being underweight (BMI<18·5 kg/m2) is associated with significantly higher mortality than being of normal weight, especially among smokers. We aimed to explore in a generally lean population whether being underweight is significantly associated with increased all-cause mortality.nnnDESIGNnProspective cohort study.nnnSETTINGnKorea Medical Insurance Corporation study with 14 years of follow-up.nnnSUBJECTSnAfter excluding deaths within the first 5 years of follow-up (1993-1997) to minimize reverse causation and excluding participants without information about smoking and health status, 94 133 men and 48 496 women aged 35-59 years in 1990 were included.nnnRESULTSnWe documented 5411 (5·7 %) deaths in men and 762 (1·6 %) in women. Among never smokers, hazard ratios (HR) for underweight individuals were not significantly higher than those for normal-weight individuals (BMI=18·5-22·9 kg/m2): HR=0·87 (95 % CI 0·41, 1·84, P=0·72) for underweight men and HR=1·12 (95 % CI 0·76, 1·65, P=0·58) for underweight women. Among ex-smokers, HR=0·86 (95 % CI 0·38, 1·93, P=0·72) for underweight men and HR=3·77 (95 % CI 0·42, 32·29, P=0·24) for underweight women. Among current smokers, HR=1·60 (95 % CI 1·28, 2·01, P<0·001) for underweight men and HR=2·07 (95 % CI 0·43, 9·94, P=0·36) for underweight women.nnnCONCLUSIONSnThe present study does not support that being underweight per se is associated with increased all-cause mortality in Korean men and women.

Residential radon and environmental burden of disease among Non-smokers.

BackgroundLung cancer was the second highest absolute cancer incidence globally and the first cause of cancer mortality in 2014. Indoor radon is the second leading risk factor of lung cancer after cigarette smoking among ever smokers and the first among non-smokers. Environmental burden of disease (EBD) attributable to residential radon among non-smokers is critical for identifying threats to population health and planning health policy.MethodsTo identify and retrieve literatures describing environmental burden of lung cancer attributable to residential radon, we searched databases including Ovid-MEDLINE, -EMBASE from 1980 to 2016. Search terms included patient keywords using ‘lung’, ‘neoplasm’, exposure keywords using ‘residential’, ‘radon’, and outcomes keywords using ‘years of life lost’, ‘years of life lost due to disability’, ‘burden’. Searching through literatures identified 261 documents; further 9 documents were identified using manual searching. Two researchers independently assessed 271 abstracts eligible for inclusion at the abstract level. Full text reviews were conducted for selected publications after the first assessment. Ten studies were included in the final evaluation.ReviewGlobal disability‐adjusted life years (DALYs)(95xa0% uncertainty interval) for lung cancer were increased by 35.9xa0% from 23,850,000(18,835,000-29,845,000) in 1900 to 32,405,000(24,400,000-38,334,000) in 2000. DALYs attributable to residential radon were 2,114,000(273,000-4,660,000) DALYs in 2010. Lung cancer caused 34,732,900(33,042,600u2009~u200936,328,100) DALYs in 2013. DALYs attributable to residential radon were 1,979,000(1,331,000-2,768,000) DALYs for in 2013. The number of attributable lung cancer cases was 70-900 and EBD for radon was 1,000-14,000 DALYs in Netherland. The years of life lost were 0.066xa0years among never-smokers and 0.198xa0years among ever-smoker population in Canada.ConclusionIn summary, estimated global EBD attributable to residential radon was 1,979,000 DALYs for both sexes in 2013. In Netherlands, EBD for radon was 1,000–14,000 DALYs. Smoking population lost three times more years than never-smokers in Canada. There was no study estimating EBD of residential radon among never smokers in Korea and Asian country. In addition, there were a few studies reflecting the age of building, though residential radon exposure level depends on the age of building. Further EBD study reflecting Korean disability weight and the age of building is required to estimate EBD precisely.

Indoor radon exposure and lung cancer: a review of ecological studies

Lung cancer has high mortality and incidence rates. The leading causes of lung cancer are smoking and radon exposure. Indeed, the World Health Organization (WHO) has categorized radon as a carcinogenic substance causing lung cancer. Radon is a natural, radioactive substance; it is an inert gas that mainly exists in soil or rock. The gas decays into radioactive particles called radon progeny that can enter the human body through breathing. Upon entering the body, these radioactive elements release α-rays that affect lung tissue, causing lung cancer upon long-term exposure thereto. Epidemiological studies first outlined a high correlation between the incidence rate of lung cancer and exposure to radon progeny among miners in Europe. Thereafter, data and research on radon exposure and lung cancer incidence in homes have continued to accumulate. Many international studies have reported increases in the risk ratio of lung cancer when indoor radon concentrations inside the home are high.Although research into indoor radon concentrations and lung cancer incidence is actively conducted throughout North America and Europe, similar research is lacking in Korea. Recently, however, studies have begun to accumulate and report important data on indoor radon concentrations across the nation. In this study, we aimed to review domestic and foreign research into indoor radon concentrations and to outline correlations between indoor radon concentrations in homes and lung cancer incidence, as reported in ecological studies thereof.Herein, we noted large differences in radon concentrations between and within individual countries. For Korea, we observed tremendous differences in indoor radon concentrations according to region and year of study, even within the same region. In correlation analysis, lung cancer incidence was not found to be higher in areas with high indoor radon concentrations in Korea.Through our review, we identified a need to implement a greater variety of statistical analyses in research on indoor radon concentrations and lung cancer incidence. Also, we suggest that cohort research or patient-control group research into radon exposure and lung cancer incidence that considers smoking and other factors is warranted.

Trends in research on indoor radon exposure and lung cancer in South Korea

Editorial Radon is recognized by the World Health Organization as a lung cancer-causing carcinogen in humans, and is the second most common cause of lung cancer after smoking [1]. A causal relationship between radon and lung cancer was first described in epidemiological studies on underground mine workers. Thereafter, case–control studies further demonstrated that exposure to low concentrations of radon carries a risk for lung cancer. Recently, pooling studies have set out to investigate lung cancer risk in relation to exposure to radon indoors. In South Korea, a total of 47,869 men died from cancer in 2014, comprising 32.5 % of all male deaths that year. Among these Korean men, lung cancer had the highest mortality rate, compared to all other cancer types, and accounted for 12,785 deaths, corresponding to 26.7 % of all deaths from cancer. Meanwhile, in the same year, a total of 28,742 women died from cancer in South Korea, comprising 23.9 % of all deaths among women. As in men, lung cancer exhibited the highest mortality rate, accounting for 4655 deaths (16.2 % of all deaths from cancer) [2]. As the incidence of lung cancer has continued to increase, studies have been undertaken to outline the etiology thereof. Histologically, lung cancer is primarily classified into small cell lung cancers (about 20 % of all lung cancers) and non-small cell lung cancers (80 %); non-small cell lung cancer is further subdivided into adenocarcinoma (40 %), squamous cell carcinoma (30 %), and large cell carcinoma (15 %). Small cell lung cancer is typically malignant, and in most cases, metastasizes to other organs before it is detected. Generally, smoking is considered to be the main cause of lung cancer: small cell lung cancers and squamous cell carcinoma are positively associated with smoking, whereas adenocarcinoma exhibits relatively lower correlation with smoking [2–4]. Meanwhile, however, 10–25 % of all cases of lung cancer are not directly related to smoking [5]. Reports suggest that passive smoking increases the risk of lung cancer by 35 % in men and 25 % in women [6]. Lung cancer has also been found to be related with radon exposure, exposure to potential lung carcinogens (asbestos, polycyclic hydrocarbons, silica, heavy metals, etc.), oil vapor when cooking, coal combustion, hormonal factors, and air pollution [7]. Despite awareness of radon’s association with lung cancer, Koreans are less aware of the potential risks of indoor radon exposure. This paper aimed to review trends in studies on indoor radon exposure and lung cancer in South Korea, to suggest the need to establish reference levels for indoor radon levels specific to South Korea, and to highlight the necessity of continuous indoor radon exposure-related research. In this article, we outline eight papers published on indoor radon exposure and lung cancer with respect to Korea, covering topics related to epidemiological studies, mathematical-statistical modeling, environmental burden of disease, genetics biomarkers, and radon measurement methods. The following summarizes our findings from reviewing research on indoor radon exposure:

Impact of Serum Leptin to Adiponectin Ratio on Regression of Metabolic Syndrome in High-Risk Individuals: The ARIRANG Study

Purpose The ratio of serum leptin to adiponectin (L/A ratio) could be used as a marker for insulin resistance. However, few prospective studies have investigated the impact of L/A ratio on improvement of metabolic components in high-risk individuals with metabolic syndrome. We examined the association between L/A ratio and the regression of metabolic syndrome in a population-based longitudinal study. Materials and Methods A total of 1017 subjects (431 men and 586 women) with metabolic syndrome at baseline (2005–2008) were examined and followed (2008–2011). Baseline serum levels of leptin and adiponectin were analyzed by radioimmunoassay. Area under the receiver operating characteristics curve (AUROC) analyses were used to assess the predictive ability of L/A ratio for the regression of metabolic syndrome. Results During an average of 2.8 years of follow-up, metabolic syndrome disappeared in 142 men (32.9%) and 196 women (33.4%). After multivariable adjustment, the odds ratios (95% confidence interval) for regression of metabolic syndrome in comparisons of the lowest to the highest tertiles of L/A ratio were 1.84 (1.02–3.31) in men and 2.32 (1.37–3.91) in women. In AUROC analyses, L/A ratio had a greater predictive power than serum adiponectin for the regression of metabolic syndrome in both men (p=0.024) and women (p=0.019). Conclusion Low L/A ratio is a predictor for the regression of metabolic syndrome. The L/A ratio could be a useful clinical marker for management of high-risk individuals with metabolic syndrome.