Household and area income levels are associated with smoking status in the Korean adult population

National and Regional Trends in the Prevalence of Hypertension in South Korea Amid the Pandemic, 2009-2022: Nationwide Study of Over 3 Million Individuals

BACKGROUND

Understanding the association between hypertension prevalence and socioeconomic and behavioral variables during a pandemic is essential, and this analysis should extend beyond short-term trends.

OBJECTIVE

This study aims to examine long-term trends in the prevalence of participants diagnosed with and receiving treatment for hypertension, using data collected by a nationally representative survey from 2009 to 2022, which includes the COVID-19 pandemic era.

METHODS

A nationwide, population-based, cross-sectional study used data collected from the South Korea Community Health Survey between 2009 and 2022. The study sample comprised 3,208,710 Korean adults over a period of 14 years. We aimed to assess trends in the prevalence of participants diagnosed with and receiving treatment for hypertension in the national population from 2009 to 2022, with a specific focus on the COVID-19 pandemic, using weighted linear regression models.

RESULTS

Among the included 3,072,546 Korean adults, 794,239 (25.85%) were aged 19-39 years, 1,179,388 (38.38%) were aged 40-59 years; 948,097 (30.86%) were aged 60-79 years, and 150,822 (4.91%) were aged 80 years or older. A total of 1,426,379 (46.42%) were men; 761,896 (24.80%) and 712,264 (23.18%) were diagnosed with and received treatment for hypertension, respectively. Although the overall prevalence over the 14-year period increased, the upward trends of patients diagnosed with and receiving treatment for hypertension decreased during the COVID-19 pandemic era compared with the prepandemic era (β difference for trend during vs before the pandemic -.101, 95% CI -0.107 to -0.094 vs -.133, 95% CI -0.140 to -0.127). Notably, the trends in prevalence during the pandemic were less pronounced in subgroups of older adults (≥60 years old) and individuals with higher alcohol consumption (≥5 days/month).

CONCLUSIONS

This nationwide representative study found that the national prevalence of participants diagnosed with and receiving treatment for hypertension increased during the prepandemic era. However, there was a marked decrease in these trends during the prepandemic era, compared with the pandemic era, particularly among specific subgroups at increased risk of negative outcomes. Future studies are needed to evaluate the factors associated with changes in the prevalence of hypertension during the COVID-19 pandemic.

Influencing factors of good quality of life among chronic obstructive pulmonary disease patients living in Zhejiang Province, China

Chronic obstructive pulmonary disease (COPD) is a chronic, progressive and debilitating disease that affects quality of life (QOL), especially among patients living in poor environments. This study aimed to determine the influencing factors of good QOL among COPD patients living in Zhejiang, China. A cross-sectional study was conducted to collect data from participants in six tertiary hospitals in Zhejiang Province by a simple random sampling method. A validated questionnaire was used to collect general information, environmental factors, and COPD stage. The standardized St. George's Respiratory Questionnaire (SGRQ) was used to assess QOL. Logistic regression was used to determine influencing factors of good QOL among COPD patients at a significance level of α = 0.05. A total of 420 participants were recruited for analysis. The overall prevalence of patients with good QOL was 25.7%. Six variables were found to be associated with good QOL in the multivariable analysis. Patients who were employed had 2.35 times (95% CI 1.03-5.34) greater odds of having good QOL than those who were unemployed. Those whose family income was higher than 100,000 CNY had 2.49 times (95% CI 1.15-5.39) greater odds of having good QOL than those whose family income was lower than 100,000 CNY. Those who had treatment expenses less than 5,000 CNY had 4.57 (95% CI 1.57-13.30) times greater odds of having good QOL than those who had treatment expenses of 5,000 CNY or higher. Those who had mild or moderate airflow limitation were 5.27 times (95% CI 1.61-17.26) more likely to have good QOL than those who were in a severe or very severe stage of COPD. Those who had a duration of illness less than 60 months had 5.57 times (95% CI 1.40-22.12) greater odds of having good QOL than those who had a duration of illness of 120 months or more. Those who were not hospitalized within the past 3 months had 9.39 times (95% CI 1.62-54.43) greater odds of having good QOL than those who were hospitalized more than twice over the past 3 months. Socioeconomic status, disease stage and accessibility were associated with good QOL among COPD patients in Zhejiang Province, China. Increasing family income and implementing measures to improve the accessibility of medical care, including developing a proper system to decrease the cost of treatment for COPD patients, can improve patients' QOL.

Longitudinal analysis of the impact of smoking exposure on atopic indices and allergies in early childhood

Background

Exposure to smoking is recognized as a health hazard; however, a longitudinal analysis of the impact of smoking exposure in families on the allergic reactions related to childhood atopic diseases has not been well addressed.

Methods

Children who completed a three-year follow-up period from the birth cohort were included in this study. The history of smoking exposure was recorded, and the urine cotinine levels were measured at 1 and 6 months, and 1, 2, and 3 years of age. Specific IgE levels against food and mite allergens were measured at age 6 months, and 1, 2, and 3 years. Their relevance to family smoking exposure and the subsequent development of atopic diseases was also analyzed. This study was approved by the Ethics Committee of Chang Gung Memorial Hospital (No. 102-1842C).

Results

A total of 198 infants were enrolled in this study. The prevalence of passive smoking exposure among these children was as high as 45%. The urine cotinine levels were significantly higher in children with history of smoking exposure (P < 0.001). At 6 months of age, the food-specific IgE levels and the prevalence of eczema were significantly higher in children with smoking exposure than in those without smoking exposure (P < 0.05). By contrast, the urine cotinine levels were significantly higher in children with IgE sensitization (>100 kU/L, P < 0.05) at 3 years of age, which was also significantly associated with a higher prevalence of allergic rhinitis and development of asthma (P < 0.01).

Conclusion

Family smoking exposure appears to be strongly associated with food sensitization in infancy and with IgE production in later childhood. This could potentially increase the susceptibility of developing infantile eczema and subsequent childhood airway allergies.

Exhaled Carbon Monoxide Level and Practices among Tobacco and Nicotine Adult Users in Klang Valley, Malaysia

Tobacco and nicotine derivatives uses are multiple in nature. These include conventional cigarettes (CCs), heated tobacco products (HTPs), and electronic cigarettes (ECs). This study aims to determine the practices, nicotine dependency profile, association with exhaled carbon monoxide (eCO) level, and pulmonary function (PF) among adult product users and non-smokers. This cross-sectional study involved smokers, nicotine users, and non-smokers from two public health facilities in Kuala Lumpur from December 2021 to April 2022. Data on socio-demography, smoking profile, nicotine dependency level, anthropometry, eCO monitor, and spirometer measurements were recorded. Out of 657 respondents, 52.1% were non-smokers, 48.3% were CC only smokers, poly-users (PUs) (27.3%), EC-only users (20.9%), and HTP-only users (3.5%). EC use was prevalent among the younger aged, tertiary educated, and females; HTP use was prevalent among those of an older age and CC users was common among lower educated males. The highest median eCO (in ppm) seen were as follows: in CC users only (13.00), PUs (7.00), EC users (2.00), HTP users (2.00), and the least was observed among non-smokers (1.00), which is significantly different across the groups (p <0.001). Comparison of practice between the different product users showed significant differences in age of product initiation (p <0.001, youngest in CC users in PUs), duration of product use (p <0.001, longest in exclusive CC users), cost per month (p <0.001, highest in exclusive HTP users) and attempt to quit product (p <0.001, CC use in PUs had the highest attempt to quit), while there is no significant difference in Fagerström score across the groups. Among EC users, 68.2% successfully switched from smoking CCs to ECs. The findings suggest that EC and HTP users are exhaling less CO. The use of these products in a targeted approach may manage nicotine addiction. Switching practice was higher among current EC users (from using CCs), hence emphasizing the need of switching encouragement and total nicotine abstinence later on. Lower eCO levels in the PU group, (as compared to CC-only users) and high quit attempt rate among in CC use in PUs may indicate attempt of PUs in reducing CC use through alternative modalities such as ECs and HTPs.

Gender differences in social environmental changes associated with smoking: a cross-sectional study from Chinese internal migrants

OBJECTIVES

To identify clues for women's tobacco control, this study analyses the gender differences in social environmental changes associated with smoking and the interaction between the environment and individuals' social integration.

DESIGN, SETTING AND PARTICIPANTS

A cross-sectional design and secondary analysis were used among Chinese internal migrants. Data were from the 2012 Migrant Dynamics Monitoring Survey in China with participants aged 15-59 years old (75 416 women and 83 140 men) who resided in cities for more than 1 month.

PRIMARY AND SECONDARY OUTCOME MEASURES

Social environmental changes were measured by differences in smoking prevalence and women's empowerment between the migrant-receiving province (MRP) and migrant-sending province (MSP). Social participation and duration of stay (DOS) were adopted as indicators of social integration. Stratified analysis and binary logistic regression models were used to determine the dependent variable (smoking status) and environmental changes after controlling for age, education, income and happiness.

RESULTS

Differences in the smoking prevalence environment (lower in MRP, OR 0.70, 95% CI 0.60 to 0.83; higher rate in MRP, OR 1.79, 95% CI 1.35 to 2.37) and women's empowerment (lower rate in MRP, OR 0.80, 95% CI 0.68 to 0.97; higher rate in MRP, OR 1.15, 95% CI 1.00 to 1.33) between MRP and MSP were positively correlated with women's smoking. In men, however, migrating to an area with lower smoking prevalence could not reduce smoking risk, whereas moving to an area with higher women's empowerment could. A long DOS was an independent risk factor for smoking in women (ranged from 1.20 to 2.00 in various environmental changes scenarios) but a protective factor for men. An interaction between environmental changes and social integration could not be verified.

CONCLUSIONS

Tobacco control strategies should consider gender differences, especially women who are experiencing social environmental changes.

Association of indoor noise level with depression in hotel workers: A multicenter study from 111 China's cities

Several studies have elucidated the link between outdoor noise and depression, but the relationship between indoor noise levels and depression symptoms in residential and public places remains unclear. This study was a multicenter observational study with a cross-sectional design. In 2019, a total of 10 545 indoor noise levels on-site and 26 018 health data from practitioners were collected from 2402 hotels in 111 cities. Indoor daily noise data levels were detected, and PHQ-9 questionnaires were used to collect health data. Logistic analysis was used to determine the association between depression score and noise level, negative binomial regression was used to determine potential risks. The geometric mean indoor noise level was 38.9 dB (A), with approximately 40.9% of hotels exceeding the 45 dB value (A). Approximately 19.1% of hotel workers exhibited mild and above depressive symptoms. In addition to functional zoning, geographic location, central air conditioner, decoration status, and other factors had an impact on noise levels (p < 0.05). Results of logistic and negative binomial regression showed the following: (1) there was significantly positive association between indoor noise and high depression scores above 2 (OR = 1.007, 95% CI: 1.002, 1.012) and (2) some sub-groups were more susceptible to this effect, especially for the younger female workers working in the first-tier cities, having higher education level, lower level of income, smoking, and longer working hours. This study confirms an early potential effect of indoor noise on depression. It is recommended to implement evidence-based measures to control noise sources in hotels.

Network Analysis of Demographics, Dietary Intake, and Comorbidity Interactions

The aim of this study was to elucidate the complex interrelationships among dietary intake, demographics, and the risk of comorbidities. We applied a Gaussian graphical model to calculate the dietary scores of the participants. The network structure of dietary intake, demographics, and comorbidities was estimated in a mixed graphical model. The centrality indices of the nodes (strength (S), closeness (C), and betweenness (B)) were measured to identify the central node. Multinomial logistic regression was used to examine the association between the factors and comorbidities. Among 7423 participants, the strongest pairwise interactions were found between sex and smoking (1.56), sex and employment (0.66), sex and marital status (0.58), marital status and income (0.65), and age and employment (0.58). Among the factors in the network, sex played a central role (S = 4.63, C = 0.014, B = 41), followed by age (S = 2.81, C = 0.013, B = 18), smoking (S = 2.72, C = 0.013, B = 0), and employment (S = 2.17, C = 0.014, B = 22). While the odds of hypertension and diabetes were significantly higher among females than males, an inverse association was observed between high cholesterol and moderate chronic kidney disease. Among these factors, dietary intake was not a strongly interacting factor in the network, whereas age was consistently associated with the comorbidities of hypertension, high cholesterol, diabetes, and chronic kidney disease.

Impact of smoking on the development of idiopathic pulmonary fibrosis: results from a nationwide population-based cohort study

BACKGROUND

Smoking has been considered an important risk factor for idiopathic pulmonary fibrosis (IPF) incidence. However, there are no population-based large-scale studies demonstrating the effects of smoking on the development of IPF. We aimed to evaluate the effect of smoking on IPF development using a nationwide population-based cohort.

METHODS

Using the Korean National Health Information Database, we enrolled individuals who had participated in the health check-up service between 2009 and 2012. Participants having a prior diagnosis of IPF were excluded. The history of smoking status and quantity was collected by a questionnaire. We identified all cases of incident IPF through 2016 on the basis of ICD-10 codes for IPF and medical claims. Cox proportional hazards models were used to calculate the adjusted HR (aHR) of the development of IPF.

RESULTS

A total of 25 113 individuals (0.11%) with incident IPF were identified out of 23 242 836 participants registered in the database. The risk of IPF was significantly higher in current and former smokers than in never smokers, with an aHR of 1.66 (95% CI 1.61 to 1.72) and 1.42 (95% CI 1.37 to 1.48), respectively. Current smokers had a higher risk of IPF than former smokers (aHR 1.17, 95% CI 1.13 to 1.21). The risk of IPF development increased as the smoking intensity and duration increased.

CONCLUSION

Smoking significantly increased the risk of IPF development. Current smokers had a higher risk of IPF than former smokers. A dose-response relationship was observed between smoking and the development of IPF.

Positive Effects of the National Cigarette Price Increase Policy on Smoking Cessation in South Korea

Background

In January 2015, South Korea's government raised the cigarette tax, and the retail price of cigarettes abruptly increased by 80% compared to the previous year. This research aimed to determine the effect of this increase on smoking cessation among South Korean smokers.

Methods

We analyzed data collected by the 2013–2015 South Korea National Health and Nutrition Examination Survey of 15,203 South Koreans over 19 years old using regression analysis. We examined the recent non-smoking period of nonsmoking people, prepared according to the survey, and analyzed the recent smoking cessation ratio.

Results

Among smokers, from 2013 to 2014, the smoking cessation rate was 7.2%, and it increased to 9.9% in 2015 after the increase in the cigarette tax. In 2015, the recent smoking cessation rate was higher among people over the age of 60 (odds ratio [OR], 2.67) compared to those between the ages of 40 and 49. The recent smoking cessation rate was higher among people with below elementary education (OR, 2.28) and above university education (OR, 1.94) compared to high school, higher for those with apartments (OR, 1.74) compared to general type residences, and higher among those with a household income in the low-middle quartile (Q2) (OR, 2.32) compared to the highest quartile (Q4).

Conclusion

This innovative policy including increase in cigarette prices affected smoking cessation, and its impact varied by sub-group of smokers in South Korea.

Factors Associated with Single-Use and Co-Use of Tobacco and Alcohol: A Multinomial Modeling Approach

Tobacco smoking and alcohol consumption are among the most important public health concerns not only in South Korea but also globally. This study identified the factors associated with single-use and co-use of tobacco and alcohol in Korean adults and provided more accurate estimates using a multinomial modeling approach. This study used the Korea Community Health Survey Data 2017, of which 205,336 respondents were selected as the sample for a multinomial logistic regression analysis. For the group that identified as only drinking monthly compared to the reference group, we found that the direction of the following factors was opposite to that of the results of the only currently smoking group: Age, marital status, educational level, monthly household income, occupation, obesity, self-rated health, hypertension, and hyperlipidemia. For the currently smoking and drinking monthly group relative to the reference group, the overall direction was a mix of the results of only currently smoking and only drinking monthly. These findings support the development of policies that consider the risk of smoking tobacco and consuming alcohol simultaneously.

Socioeconomic disparities in prevalence and behaviors of smoking in rural Southwest China

Background

This study examines how prevalence and behaviors of smoking differ by socioeconomic status among rural southwest Chinese adults.

Methods

A cross-sectional survey was conducted including 7743 adults aged ≥35 years in rural regions of Yunnan Province, China from 2016 to 2018. Information on individual socioeconomic status (SES), ethnicity, and self-reported smoking behaviors was collected utilizing a standardized questionnaire. The individual socioeconomic position (SEP) index was constructed using principal component analysis. Multivariate logistic regression models were used to analyze the association between individual SES variables and the prevalence and behaviors of smoking.

Results

In the study population, the overall prevalence rate of current smokers was 33.5%. Males had a markedly higher prevalence of current smokers than females (62.6% vs. 4.8%, P < 0.01). Of these smokers, 74.5% began smoking during adolescence, 88.8% had never attempted to quit smoking, and 81.1% reported smoking in public places. Ethnic minority participants and those with low levels of education and/or low SEP were more likely to use tobacco as well as more likely to start smoking, and regularly smoke, during adolescence (P < 0.01). Participants with poor access to medical services had a higher prevalence of current smoking than their counterparts (P < 0.01). Among current smokers, Han ethnicity, good access to medical services, and high SEP were positively associated with the probability of having attempted to quit smoking at least once, while a high level of education and high SEP were negatively associated with the probability of smoking in public places.

Conclusions

Disparities in prevalence and behaviors of smoking exist across a diversity of indicators of individual SES in rural southwest China. Future tobacco cessation interventions should focus on men, ethnic minorities, and those with low education levels, poor access to medical services, and low SEP.

Socioeconomic status and depression as combined risk factors for acute myocardial infarction and stroke: A population-based study of 2.7 million Korean adults

OBJECTIVES

To evaluate the separate and combined associations of socioeconomic status (SES) and depression with the incidences of acute myocardial infarction (AMI) and stroke.

METHODS

We conducted a population-based cohort study using nationwide health insurance claims data collected from 2002 to 2016 in South Korea. A total of 2,705,090 subjects aged 20 years or older for whom had health screening data were collected between 2004 and 2005 were analyzed. The hazard ratios (HRs) for the incidences of AMI and stroke were calculated using Cox proportional regression analyses.

RESULTS

After adjusting for cardiovascular risk factors, a low SES was associated with increased risks of AMI (HR, 1.16; 95% confidence interval (CI), 1.14-1.19) and stroke (HR, 1.13; 95% CI, 1.11-1.14) incidence. Depression was also associated with an increased incidence of AMI (HR, 1.26; 95% CI, 1.21-1.31) and stroke (HR, 1.24; 95% CI, 1.21-1.27). Patients with depression who had a low SES exhibited significantly increased risks of AMI (HR, 1.47; 95% CI, 1.36-1.60) and stroke (HR, 1.37; 95% CI, 1.30-1.44) compared to patients with a high SES who were not diagnosed with depression. Depression showed a positive effect modification of low and medium SES compared to high SES on the association with AMI but not with stroke.

CONCLUSIONS

Subjects with both a low SES and depression displayed the highest risk. Both SES and depression should be considered in cardiovascular risk assessments, particularly in individuals with depression who have a low SES.

The price of tobacco and its effects on smoking behaviors in Korea: The 2015 Korea Community Health Survey

This study investigated the effects of the price of tobacco on smoking behaviors in Korean adult smokers using a population-based survey. Current smokers or former smokers who quit smoking <1 year prior to the survey were selected from the data of 2015 Korea Community Health Survey (N = 45,686). The effects of the price of tobacco on smoking behaviors were measured. The major effects were defined as quitting, reducing smoking and using electronic cigarettes (e-cigarettes). Chi-square tests and multiple logistic regression analyses were performed. After tobacco prices increased, 3.8%, 22.8% and 5.4% of subjects quit, reduced smoking and switched to e-cigarettes. The adjusted odds ratio (aOR) for reducing smoking was significantly higher in subjects with a lower household income and lower education level than in those with a greater income and higher education level among current smokers. Subjects who started smoking at an older age, who smoked a smaller number of cigarettes smoked per day and who had been exposed to anti-smoking campaigns and anti-smoking information were more likely to reduce smoking after the price of tobacco increased. Younger subjects were less likely to reduce smoking, but they were more likely to use e-cigarettes after the price of tobacco increased. Low-income subjects were sensitive to increases in the price of tobacco. Additional strategies are required to change the smoking behaviors of heavy smokers. Future studies should investigate the long-term effects of increasing the price of tobacco, especially on younger adults, on smoking behaviors.

The Association between Socioeconomic Status, Smoking, and Chronic Disease in Inner Mongolia in Northern China

The interactive associations of socioeconomic status (SES) and smoking with chronic disease were investigated with a view to expanding the evidence to inform tobacco policies and interventions in Northern China. The fifth NHSS (National Health Service Survey) 2013 in Inner Mongolia was a population-based survey of national residents, aged 15 years and older, in which multi-stage stratified cluster sampling methods were used to survey 13,554 residents. The SES was measured by scores derived from levels of education level and household annual income. Multivariate logistic regression models were performed to determine the association between SES, smoking, and chronic disease adjusted by confounders. Three thousand nine hundred and thirty-seven residents (32.29%) were identified as current smokers and 3520 residents (26.01%) had been diagnosed with chronic diseases. In the males, former smoking with low SES had the highest risk of one chronic disease, with an odds ratio (OR) of 2.505 (95% confidence interval [95% CI] (OR = 2.505, 95% CI: 1.635–3.837) or multiple chronic diseases (OR = 2.631, 95% CI: 1.321–5.243). In the females, current smoking with low SES had the highest risk of one chronic disease (OR = 3.044, 95% CI: 2.158–4.292). The conclusion of this study was that residents with combined ever-smoking and low SES deserved more attention in the prevention and control of chronic disease.

Comparison of District-level Smoking Prevalence and Their Income Gaps from Two National Databases: the National Health Screening Database and the Community Health Survey in Korea, 2009-2014

BACKGROUND

We compared age-standardized prevalence of cigarette smoking and their income gaps at the district-level in Korea using the National Health Screening Database (NHSD) and the Community Health Survey (CHS).

METHODS

Between 2009 and 2014, 39,049,485 subjects participating in the NHSD and 989,292 participants in the CHS were analyzed. The age-standardized prevalence of smoking and their interquintile income differences were calculated for 245 districts of Korea. We examined between-period correlations for the age-standardized smoking prevalence at the district-level and investigated the district-level differences in smoking prevalence and income gaps between the two databases.

RESULTS

The between-period correlation coefficients of smoking prevalence for both genders were 0.92-0.97 in NHSD and 0.58-0.69 in CHS, respectively. When using NHSD, we found significant income gaps in all districts for men and 244 districts for women. However, when CHS was analyzed, only 167 and 173 districts for men and women, respectively, showed significant income gaps. While correlation coefficients of district-level smoking prevalence from two databases were 0.87 for men and 0.85 for women, a relatively weak correlation between income gaps from the two databases was found.

CONCLUSION

Based on two databases, income gaps in smoking prevalence were evident for nearly all districts of Korea. Because of the large sample size for each district, NHSD may provide stable district-level smoking prevalence and its income gap and thus should be considered as a valuable data source for monitoring district-level smoking prevalence and its socioeconomic inequality.

Gender balance and its impact on male and female smoking rates in Chinese cities

OBJECTIVE

Although gender differences in smoking have received much attention, few studies have explored the importance of contextual effects on male and female smoking rates. The aim of this study is to examine the association between variations in city-level sex ratios and gender differences in smoking in China.

METHODS

Participants included 16,866 urban residents, who were identified through multi-stage sampling conducted in 21 Chinese cities.

RESULTS

The study found that, independent of personal characteristics, cities with more males had higher male smoking rates and lower female rates.

CONCLUSIONS

Our research underscores the importance of city-level contextual effects in understanding gender differences in smoking in China.

Relationship Between Hiding Emotions and Health Outcomes Among South Korean Interactive Service Workers

The purpose of this study was to examine the relationships among hiding emotions, psychological well-being, and presenteeism for South Korean interactive service workers. This study is a secondary analysis of data extracted from the 2011 Korean Working Conditions Survey (KWCS), a longitudinal study conducted by the Korea Occupational Safety and Health Agency (KOSHA). For the present analysis, 15,669 workers who interacted with others at work were selected. Based on existing literature, a set of variables was chosen from the KWCS. Psychological well-being was measured using the World Health Organization (WHO)-5 Well-Being Index. The results indicated that frequently hiding feelings is related to presenteeism. Also, among workers who hide emotions at work, an inverse relationship was found between the degree to which these workers hide their feelings and their psychological well-being. Based on these results, the researchers offered practical suggestions to assist interactive service workers adjust to duties that require emotion management.

Individual- and community-level social gradients of edentulousness

Background

Community-level factors as well as individual-level factors affect individual health. To date, no studies have examined the association between community-level social gradient and edentulousness. The aim of this study was to investigate individual- and community-level social inequalities in edentulousness and to determine any explanatory factors in this association.

Methods

We analyzed the data from the Japan Gerontological Evaluation Study (JAGES). In 2010-2012, 112,123 subjects aged 65 or older responded to the questionnaire survey (response rate = 66.3%). Multilevel logistic regression analysis was applied to determine the association between community-level income and edentulousness after accounting for individual-level income and demographic covariates. Then, we estimated the probability of edentulousness by individual- and community-level incomes after adjusted for covariates.

Results

Of 79,563 valid participants, the prevalence of edentulousness among 39,550 men (49.7%) and 40,013 women (50.3%) were both 13.8%. Living in communities with higher mean incomes and having higher individual-level incomes were significantly associated with a lower risk of edentulousness (odds ratios [ORs] by 10,000 USD increments were 0.37 (95% confidence interval [CI] [0.22-0.63]) for community-level and 0.85 (95% CI [0.84-0.86]) for individual-level income). Individual- and community-level social factors, including density of dental clinics, partially explained the social gradients. However, in the fully adjusted model, both community- and individual-level social gradients of edentulousness remained significant (ORs = 0.43 (95% CI [0.27-0.67]) and 0.90 (95% CI [0.88-0.91]), respectively). One standard deviation changes in community- and individual-level incomes were associated with 0.78 and 0.84 times lower odds of edentulousness, respectively. In addition, compared to men, women living in communities with higher average incomes had a significantly lower risk of edentulousness (p-value for interaction < 0.001).

Conclusions

Individual- and community-level social inequalities in dental health were observed. Public health policies should account for social determinants of oral health when reducing oral health inequalities.