National Health Insurance Beneficiaries Research Articles

Influence of Socioeconomic Status on the Presence of Obstructive Coronary Artery Disease and Cardiovascular Outcomes in Patients Undergoing Invasive Coronary Angiography.

This retrospective study investigated the impact of socioeconomic status (SES) on patients at high risk of cardiovascular disease, focusing on obstructive coronary artery disease (CAD) presence and long-term cardiovascular outcomes in individuals undergoing invasive coronary angiography (ICA). Analyzing data from 9530 patients categorized by health insurance type (medical aid beneficiaries (MABs) as the low SES group; national health insurance beneficiaries (NHIBs) as the high SES group), this research explores the relationship between SES and outcomes. Despite a higher prevalence of cardiovascular risk factors, the MAB group exhibited similar rates of obstructive CAD compared to the NHIB group. However, over a median 3.5-year follow-up, the MAB group experienced a higher incidence of composite cardiovascular events, including cardiac death, acute myocardial infarction, coronary revascularization, and ischemic stroke, compared with the NHIB group (20.2% vs. 16.2%, p < 0.001). Multivariable Cox regression analysis, adjusting for potential confounders, revealed independently worse clinical outcomes for the MAB group (adjusted odds ratio 1.28; 95% confidence interval 1.07-1.54; p = 0.006). Despite comparable CAD rates, this study underscores the fact that individuals with low SES encounter an elevated risk of composite cardiovascular events, emphasizing the association between socioeconomic disadvantage and heightened susceptibility to cardiovascular disease, even among those already at high risk.

Prevalence of Dementia in Korea by Socioeconomic Status between Medical Aid Beneficiaries and National Health Insurance Beneficiaries

Prevalence of Dementia in Korea by Socioeconomic Status between Medical Aid Beneficiaries and National Health Insurance Beneficiaries

The Prognostic Value of Arterial Stiffness According to Socioeconomic Status.

Individuals of low socioeconomic status (SES) often exhibit increased cardiovascular risk factors and a worse prognosis. We conducted this study to ascertain whether brachial-ankle pulse wave velocity (baPWV), a straightforward and reliable measure of arterial stiffness, can hold prognostic value for people with low SES. We retrospectively analyzed a total of 1266 subjects (mean age 64.6 ± 11.6 years; 47.2% female) without documented cardiovascular disease who had undergone baPWV measurement. The subjects included 633 National Health Insurance Beneficiaries (NHIB) and 633 Medical Aid Beneficiaries (MAB), matched for major clinical features through a 1:1 propensity score matching method. Major adverse cardiovascular events (MACE), such as death, non-fatal myocardial infarction, non-fatal ischemic stroke, coronary revascularization, and heart failure necessitating admission, were assessed during the clinical follow-up. During a median follow-up period of 4.2 years (interquartile range, 2.2-5.7 years), there were 77 MACE cases (6.1%). In multivariable Cox regression analyses, baPWV was identified as a significant predictor of MACE in both groups, regardless of the use of three different baPWV criteria (median value, Asian consensus recommendation, and cut-off value obtained by receiver operating characteristic [ROC] curve analysis). In both groups, the baPWV value obtained using ROC curve analysis emerged as the best predictor of MACE. This predictive value was stronger in the NHIB group (hazard ratio, 5.80; 95% confidence interval, 2.30-14.65; p < 0.001) than in the MAB group (hazard ratio, 3.30; 95% confidence interval, 1.57-6.92; p = 0.002). baPWV was associated with future MACE incidence in both NHIB and MAB groups. Since baPWV is simple and cost-effective to measure, it could be efficiently used as a risk stratification tool for individuals with low SES.

Exploring Inequalities in the Use, Quality, and Outcome of the Diabetes Management Program of Indonesian National Health Insurance.

Access to diabetes management programs is crucial to control the increasing contribution of diabetes to the global burden of disease. However, evidence regarding whether such services are equally accessible for all population groups is still lacking, particularly in the context of low-middle-income countries and under the National Health Insurance (NHI). This study aimed to assess the extent of socioeconomic and geographical inequalities in the use, quality, and outcome of a diabetes management program for beneficiaries of Indonesian NHI. A total of 628 participants in the NHI diabetes management program in Banyumas District, Indonesia, were included in 2021 in this cross-sectional study. The main variables measured were regular visits to primary care facilities, standard medication, and glycemic control. The rate difference and rate ratio of age-sex standardized prevalence rates, as well as multiple logistic regressions, were used to measure the extent of inequalities. Around 70% of participants regularly visited primary care facilities and received standard medication, but only 35% had good glycemic control. Highly educated participants were more likely to have regular visits compared to low-educated participants (odds ratio [OR] 1.92; 95% confidence interval [95% CI]: 1.04-3.56). Based on employment and type of NHI beneficiaries, a small extent and even reverse inequalities were found although these findings were insignificant statistically. Urban residents were also more likely to have regular visits (OR 6.61; 95% CI: 2.90-15.08), receive standard medication (OR 9.73; 95% CI: 3.66-25.90), and have good glycemic control (OR 3.85; 95% CI: 1.68-8.83) compared to rural residents. Evidence on the extent of socioeconomic inequalities is inconclusive but substantial geographical inequalities in the use, quality, and outcome of diabetes management programs exist among Indonesian NHI beneficiaries. Future implementation policies of the program should consider particularly the geographical characteristics of participants to avoid and reduce inequalities and, hence, the disease burden of diabetes.

The risk factors of COVID-19 infection and mortality among older adults in South Korea.

This study aimed to identify the risk factors associated with coronavirus disease 2019 (COVID-19) infection and mortality among older adults in South Korea. Using Korean National Health Insurance data from January 1, 2020, to March 31, 2022, we analyzed the impact of various factors, including age, comorbidity burden, and insurance type, on COVID-19 infection and mortality rates. Age was the most significant risk factor for mortality in older adults. A higher comorbidity burden was also associated with increased infection (odds ratio [OR]: 1.33 for Charlson Comorbidity Index [CCI] ≥2, 95% confidence interval [CI]: 1.321-1.339) and mortality (OR: 1.537 for CCI ≥2, 95% CI: 1.459-1.618) rates. While Medical Aid recipients exhibited lower infection rates (OR: 0.898, 95% CI: 0.89-0.906) than National Health Insurance beneficiaries, they had higher mortality rates (OR: 1.692, 95% CI: 1.623-1.763). These results emphasized the need to prioritize vaccination and allocate healthcare resources for older adults, particularly those with multiple comorbidities. Addressing socioeconomic disparities and ensuring equitable access to testing and healthcare services are crucial for mitigating the impact of COVID-19 on older adults.

Is Fragmented Cancer Care Associated With Medical Expenditure? Nationwide Evidence From Patients With Lung Cancer Using National Insurance Claim Data.

Objectives: We aimed to investigate the association between fragmented cancer care in the early phase after cancer diagnosis and patient outcomes using national insurance claim data. Methods: We identified National Health Insurance beneficiaries diagnosed with lung cancer in South Korea from 2010 to 2014. We included 1,364 lung cancer patients with reduced immortal time bias and heterogeneity. We performed multiple regression analysis using a generalized estimate equation with a gamma distribution for medical expenditures. Results: Among the 1,364 patients with lung cancer, 12.8% had fragmented cancer care. Healthcare costs were higher in fragmented cancer care for both during diagnosis to 365days and diagnosis to 1,825days. Linear regression results showed that fragmented cancer care was associated with 1.162 times higher costs during the period from diagnosis to 365days and 1.163 times the cost for the period from diagnosis to 1,825days. Conclusion: We found fragmented cancer care is associated with higher medical expenditure. Future health policy should consider the limitation of patients' free will when opting for fragmented cancer care, as there are currently no control mechanisms.

Unintended consequences of healthcare reform in South Korea: evidence from a regression discontinuity in time design

BackgroundTo address concerns over the financial stability of South Korea’s National Health Insurance (NHI) programme, the government transitioned from an outpatient copayment system to a coinsurance system in 2007. This policy aimed to reduce healthcare overutilization by increasing patients’ financial responsibility for outpatient services.MethodsUsing comprehensive data on NHI beneficiaries, this study employs a regression discontinuity in time (RDiT) design to assess the policy’s impact on outpatient healthcare utilization and expenditures. We focus on changes in overall outpatient visits, average healthcare cost per visit and total outpatient healthcare expenditures.ResultsOur findings indicate that the transition from outpatient copayment to coinsurance led to a substantial increase in outpatient healthcare utilization (up to 90%) while decreasing medical expenditures per visit by 23%. The policy shift incentivized beneficiaries to seek more medical treatments during the grace period and enroll in supplemental private health insurance, which provided access to additional medical services at lower marginal costs.ConclusionsThe policy change and the emergence of supplemental private insurance contributed to moral hazard and adverse selection issues, culminating in South Korea becoming the country with the highest per capita utilization of outpatient health services worldwide since 2012. This study underscores the importance of carefully considering the unintended consequences of policy interventions in the healthcare sector.

Health disparity and healthcare utilization inequity among older adults living in poverty in South Korea: a cross-sectional study

BackgroundKorea has a two-tiered universal health security system: the wage-based National Health Insurance (NHI) program and government-subsidized Medical Aid (MA) program. Beneficiaries of the MA program belong to the lowest economic class. This study aims to investigate the association between economic status—defined as NHI or MA enrollment—and health disparity of older people aged ≥ 65 years in South Korea.MethodsThe claims records of 672,525 older age population from the 2017 Health Insurance Review and Assessment Service-Adult Patient Sample were used to estimate adjusted odds ratios (aORs) of MA vs. NHI beneficiaries for prevalence for common geriatric diseases. Logistic regression and negative binomial regression were used to investigate the association between economic status and prevalence or healthcare utilization for each disease.ResultsMA beneficiaries showed significantly higher prevalence than NHI beneficiaries for seven out of nine diseases (aORs ranging from 1.18 to 1.95). The discrepancy in the prevalence between the two groups was highest among those aged 65–69 years (aORs: 1.34–2.94), and diminished as they got older (aORs: 1.05–1.67). MA beneficiaries had significantly more outpatient visits to treat six diseases (aORs: 1.07–1.28), and more hospitalization to treat seven diseases (aORs:1.08–1.73) than NHI beneficiaries.ConclusionThe higher prevalence of common geriatric diseases among MA than NHI beneficiaries confirms unfavorable health disparity in the elderly living in extreme poverty. Similar or higher healthcare utilization in treating the same conditions among MA beneficiaries suggests a low possibility of inequity for access to healthcare resources covered by the universal health security system due to poor economic status. Greater excess use of inpatient than outpatient care by MA beneficiaries implies that the condition of poor older adults might be more severe when diagnosed with the same disease.

Does fragmented cancer care affect survival? Analysis of gastric cancer patients using national insurance claim data

BackgroundWe aimed to investigate the association between fragmented cancer care in the early phase after cancer diagnosis and patient outcomes using national insurance claim data.MethodsFrom a nationwide sampled cohort database, we identified National Health Insurance beneficiaries diagnosed with gastric cancer (ICD-10: C16) in South Korea during 2005–2013. We analyzed the results of a multiple logistic regression analysis using the generalized estimated equation model to investigate which patient and institution characteristics affected fragmented cancer care during the first year after diagnosis. Then, survival analysis using the Cox proportional hazard model was conducted to investigate the association between fragmented cancer care and five-year mortality.ResultsOf 2879 gastric cancer patients, 11.9% received fragmented cancer care by changing their most visited medical institution during the first year after diagnosis. We found that patients with fragmented cancer care had a higher risk of five-year mortality (HR: 1.310, 95% CI: 1.023–1.677). This association was evident among patients who only received chemotherapy or radiotherapy (HR: 1.633, 95% CI: 1.005–2.654).ConclusionsFragmented cancer care was associated with increased risk of five-year mortality. Additionally, changes in the most visited medical institution occurred more frequently in either patients with severe conditions or patients who mainly visited smaller medical institutions. Further study is warranted to confirm these findings and examine a causal relationship between fragmented cancer care and survival.

Population-attributable risk of psychiatric disorders for suicide among adolescents and young adults in Taiwan.

Youth suicide rates have increased markedly in some countries. This study aimed to estimate the population-attributable risk of psychiatric disorders associated with suicide among Taiwanese youth aged 10-24 years. Data were obtained from the National Death Registry and National Health Insurance (NHI) claims database between 2007 and 2019. Youth who died by suicide were included, and comparisons, 1:10 matched by age and sex, were randomly selected from the Registry for NHI beneficiaries. We used multivariable logistic regression to estimate suicide odds ratios for psychiatric disorders. The population-attributable fractions (PAF) were calculated for each psychiatric disorder. A total of 2345 youth suicide and 23 450 comparisons were included. Overall, 44.8% of suicides had a psychiatric disorder, while only 7.9% of the comparisons had a psychiatric disorder. The combined PAF for all psychiatric disorders was 55.9%. The top three psychiatric conditions of the largest PAFs were major depressive disorder, dysthymia, and sleep disorder. In the analysis stratified by sex, the combined PAF was 45.5% for males and 69.2% for females. The PAF among young adults aged 20-24 years (57.0%) was higher than among adolescents aged 10-19 years (48.0%). Our findings of high PAF from major depressive disorder, dysthymia, and sleep disorder to youth suicides suggest that youth suicide prevention that focuses on detecting and treating mental illness may usefully target these disorders.

Individual socioeconomic status and risk of out-of-hospital cardiac arrest: A nationwide case-control analysis.

Area-level socioeconomic status (SES) is associated with the incidence of out-of-hospital cardiac arrest (OHCA); however, the effects of individual-level SES on OHCA occurrence are unknown. This study investigated whether individual-level SES is associated with the occurrence of OHCA. This case-control study used data from the nationwide OHCA registry and the National Health Information Database (NHID) in Korea. All adult patients with OHCA of a medical etiology from 2013 to 2018 were included. Four controls were matched to each OHCA patient based on age and sex. The exposure was individual-level SES measured by insurance type and premium, which is based on income in Korea. National Health Insurance (NHI) beneficiaries were divided into four groups (Q1-Q4), and medical aid beneficiaries were separately classified as the lowest SES group. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for the outcomes were calculated. Stratified analyses were conducted according to age and sex. A total of 105,443 cases were matched with 421,772 controls. OHCA occurred more frequently in the lower SES groups. Compared with the highest SES group (Q1), the aORs for OHCA occurrence increased as the SES decreased (aORs [95% CI] were 1.21 [1.19-1.24] for Q2, 1.33 [1.31-1.36] for Q3, 1.32 [1.30-1.35] for Q4, and 2.08 [2.02-2.13] for medical aid). Disparity by individual-level SES appeared to be greater in males than in females and greater in the young and middle-aged adults than in older adults. Low individual-level SES was associated with a higher probability of OHCA occurrence. Efforts are needed to reduce SES disparities in the occurrence of OHCA.

The impact of entering poverty on the unmet medical needs of Korean adults: a 5-year cohort study

BackgroundStudies on the effects of poverty on unmet medical needs are limited. Therefore, this study aimed to identify the impact of entering poverty on the unmet medical needs of South Korean adults.MethodsThis study used data from the Korea Health Panel Survey (2014–2018) and included 10,644 adults. Logistic regression was used to examine the impact of entering poverty on unmet medical needs (poverty status: no → no, yes → no, no → yes, yes → yes; unmet medical needs: no, yes). Poverty line was considered to be below 50% of the median income.ResultsWhen entering poverty, the proportion of unmet medical needs was 22.8% (adjusted odds ratio [AOR] 1.17, 95% confidence interval [CI] 1.01–1.36). Men (AOR 1.29, 95% CI 1.02–1.64), rural dwellers (AOR 1.24, 95% CI 1.01–1.50), and national health insurance (NHI) beneficiaries (AOR 1.21, 95% CI 1.04–1.42) were susceptible to unmet medical needs and entering poverty. Poverty line with below-median 40% had an AOR of 1.48 (95% CI 1.28–1.71). For the cause of unmet medical needs, the AORs were 1.50 for poverty (95% CI 1.16–1.94) and 1.08 for low accessibility to health care and information (95% CI 0.79–1.48).ConclusionsEntering poverty had the potential to adversely affect unmet medical needs. Men, rural dwellers, and NHI beneficiaries were vulnerable to unmet medical needs after entering poverty. Rigid definitions of poverty and inaccessibility to health care and information increase the likelihood of unmet medical needs and poverty. Society must alleviate unmet medical needs due to the increase in the population entering poverty.

The Economic Burden of Disease in France From the National Health Insurance Perspective: The Healthcare Expenditures and Conditions Mapping Used to Prepare the French Social Security Funding Act and the Public Health Act.

Background:Identifying the most frequently treated and the costliest health conditions is essential for prioritizing actions to improve the resilience of health systems.Objectives:Healthcare Expenditures and Conditions Mapping describes the annual economic burden of 58 health conditions to prepare the French Social Security Funding Act and the Public Health Act.Design:Annual cross-sectional study (2015–2019) based on the French national health database.Subjects:National health insurance beneficiaries (97% of the French residents).Measures:All individual health care expenditures reimbursed by the national health insurance were attributed to 58 health conditions (treated diseases, chronic treatments, and episodes of care) identified by using algorithms based on available medical information (diagnosis coded during hospital stays, long-term diseases, and specific drugs).Results:In 2019, €167.0 billion were reimbursed to 66.3 million people (52% women, median age: 42 y). The most prevalent treated diseases were diabetes (6.0%), chronic respiratory diseases (5.5%), and coronary diseases (3.2%). Coronary diseases accounted for 4.6% of expenditures, neurotic and mood disorders 3.7%, psychotic disorders 2.8%, and breast cancer 2.1%. Between 2015 and 2019, the expenditures increased primarily for diabetes (+€906 million) and neurotic and mood disorders (+€861 million) due to the growing number of patients. “Active lung cancer” (+€797 million) represented the highest relative increase (+54%) due to expenditures for the expensive drugs and medical devices delivered at hospital.Conclusions:These results have provided policy-makers, evaluators, and public health specialists with key insights into identifying health priorities and a better understanding of trends in health care expenditures in France.

The Risk of Herpes Zoster in Women with Polycystic Ovary Syndrome: A Retrospective Population-Based Study.

Background: The association between polycystic ovary syndrome (PCOS) and the risk of herpes zoster (HZ) remains unclear. This study investigated the risk of HZ in women with PCOS. Methods: This study used data from the Longitudinal Generation Tracking Database (LGTD 2005) which contains the information of 2 million randomly selected from National Health Insurance beneficiaries. Patients who received a diagnosis of PCOS between 2000 and 2017 were included in the PCOS cohort. Patients who were not diagnosed as having PCOS were randomly selected from the LGTD 2005 and included in the control cohort. Patients who were aged <20 years and had a history of HZ before the index date were excluded. Patients who were in both the cohorts were matched at a ratio of 1:1 through propensity score matching based on age, comorbidities, and medication. The primary outcome was the diagnosis of HZ. Results: A total of 20,142 patients were included in each case and control cohorts. The incidence rates of HZ in the PCOS and control cohorts were 3.92 and 3.17 per 1000 person-years, respectively. The PCOS cohort had a significantly higher risk of HZ than did the control cohort (adjusted hazard ratios [aHR] = 1.26). Among the patients aged 30–39 years, those with PCOS had a significantly higher risk of HZ than did those without PCOS (aHR = 1.31). Among the patients without any comorbidities, those with PCOS had a significantly higher risk of HZ (aHR = 1.26) than did those without PCOS. Conclusion: PCOS is associated with the risk of HZ, especially in young women. The risk of HZ should be addressed while treating patients with PCOS. An HZ vaccine is recommended for these patients.

Sex and Economic Disparity Related to Reperfusion Therapies for Patients with Acute Ischemic Stroke in South Korea across a 10-Year Period: A Nationwide Population-Based Study Using the National Health Insurance Database.

A complete enumeration study was conducted to evaluate trends related to reperfusion therapies (intravenous thrombolysis (IVT) and endovascular treatment (EVT)) in acute ischemic stroke (AIS) in South Korea, according to sex, economic status, and age, over a 10-year period retrospectively, using the National Health Information Database (NHIS-2020-1-481). This study included AIS patients aged ≥20 years who were hospitalized in a general hospital or tertiary hospital for ≥4 days and underwent brain imaging during the same period. Study participants were classified by sex, economic status (Medical Aid beneficiaries and National Health Insurance beneficiaries) and age (20–44, 45–64, 65–79, and ≥80 years). Women showed a significantly lower OR (Odds ratio) than men in IVT (OR: 0.75; 95% CI: 0.73–0.77), EVT (OR: 0.96; 95% CI: 0.93–0.99), and any therapy (OR: 0.82; 95% CI: 0.80–0.84). The Medical Aid beneficiaries showed significantly lower OR in IVT (OR 0.91, 95% CI 0.88–0.95), EVT (OR 0.93, 95% CI 0.89–0.98), and either therapy (OR 0.92, 95% CI 0.90–0.95) than the National Health Insurance beneficiaries. This study showed sex and economic disparity related to reperfusion therapies in patients with AIS in Korea.

Absence of an Association between Macular Degeneration and Young-Onset Dementia.

A few population-based studies have reported an association between prior age-related macular degeneration and senile dementia. No study has explored a possible link between prior macular degeneration and young-onset dementia (YOD). This case–control study aimed to evaluate the association of YOD with prior macular degeneration diagnosed in the 5-year period before their index date. Data for this retrospective observational study were retrieved from Taiwan’s National Health Insurance (NHI) dataset. A total of 36,577 patients with newly diagnosed YOD from January 2010 to December 2017 were identified as the study cohort, assigning their diagnosis date as their index date. Comparison patients were identified by propensity score-matching (three per case, n = 109,731 controls) from the remaining NHI beneficiaries of the period, their index date being the date of their first ambulatory care claim in the year of diagnosis of their matched YOD case. Chi-square test revealed no significant difference in the prevalence of prior macular degeneration between cases and controls (1.1% vs. 1.0%, p = 0.111). Conditional logistic regression analysis also showed an unadjusted odds ratio (OR) for prior macular degeneration of 1.098 among cases relative to controls (95% CI: 0.9797–1.232). Adjusted analysis confirmed that YOD was not associated with prior macular degeneration, adjusted odds ratio 1.098 (95% CI = 0.979–1.232). We conclude that patients with macular degeneration are not at increased risk for YOD.

Plantar fascial fibromatosis and herpes zoster.

PurposeInfection, chronic pain and depression are considered risk factors for herpes zoster (HZ). However, the correlation between plantar fascial fibromatosis (PFF) and HZ remains unknown. This study investigated HZ risk in patients with PFF.MethodsData was extracted from the Longitudinal Health Insurance Database 2000, which is a subsample of the Taiwan National Health Insurance (NHI) Research Database and contains 1 million NHI beneficiaries. Between 2000 and 2012, patients diagnosed as having PFF were included in the case cohort. Every case was age and sex-matched with individuals without PFF through 1:4 frequency matching (control cohort). The end of the follow-up was defined as December 31, 2013, the date of HZ diagnosis, death, emigration, or withdrawal from the NHI program.ResultsIn total, 4,729 patients were diagnosed as having PFF and were matched with 18,916 individuals without PFF. Patients with PFF were 1.23 times more likely to develop HZ than were those without PFF. Among those aged ≥65 years, patients with PFF had a higher HZ risk than did those without PFF (adjusted hazard ratio [aHR] = 1.48). Men with PFF had a significantly higher risk of HZ than did men without PFF (aHR = 1.44).ConclusionPatients with PFF, particularly older and male patients, having a high HZ risk and may thus be vaccinated for HZ.

Risk of acute kidney injury among patients with carbon monoxide poisoning.

There is a lack of evidence supporting the association between carbon monoxide (CO) poisoning and acute kidney injury (AKI). Hence, the present study aimed to evaluate the association between CO poisoning and AKI.From 2000 to 2011, we identified patients diagnosed with CO poisoning from the inpatient claims data. Patients aged below 20 years, who had a history of chronic kidney disease or end-stage renal disease before the index date and had incomplete medical information were excluded. Control patients without CO poisoning were randomly selected from all National Health Insurance beneficiaries, and the same exclusion criteria were used. The control group was frequency matched to patients with CO poisoning based on age, sex, and year of CO poisoning diagnosis. Cox proportional hazards regression analyses were conducted to assess the effects of CO poisoning on the risk of AKI. The hazard ratios and 95% confidence interval (CI) were calculated in the models.Compared with the control cohort, patients with severe CO poisoning were 3.77 times more likely to develop AKI (95% CI = 2.20-6.46), followed by those with less severe CO poisoning (adjusted hazard ratio = 2.21, 95% CI = 1.61-3.03).The findings of this nationwide study suggest an increased risk of AKI in patients with CO poisoning.

Exploration of correlation of oral hygiene and condition with influenza infection.

Influenza viruses are known to be infected through epithelial cells of the upper respiratory tract. The oral cavity is in close anatomical proximity to the upper respiratory tract, and it is conceivable that the viruses could pass through the oral cavity and infect to the upper respiratory tract. Several researchers have suggested that colonization of certain pathogenic bacteria such as Staphylococcus aureus or Streptococcus pneumoniae might affect the risk of influenza viral disease, indicating that oral hygiene and/or condition might play an important role in respiratory viral infection. Therefore, the purpose of this study was to investigate whether an oral hygiene/condition might impact influenza infection. We conducted a retrospective observational study of Japanese citizens’ regional cohort (N = 2,904) consisting of National Health Insurance beneficiaries who underwent annual health/dental examination with data entries in the Kokuho database (KDB). Trained dentists checked the oral hygiene/condition, and saliva specimens were examined using the LION dental saliva multi-test (SMT) kit. Influenza infection was identified from the diagnosis recorded in the KDB. The correlations between influenza infection and oral hygiene, dryness of the mouth, or various salivary test results were examined by a multivariate analysis adjusting for confounding factors such as gender, age, recent smoking, alcohol drinking, BMI, HbA1c, RBC for influenza infection. The logistic regression model showed that age significantly correlated with influenza infection. In addition, oral hygiene status had a nearly significant impact on influenza infection (p = 0.061), whereby, the subjects with poor oral hygiene had a higher risk of influenza infection than those with good oral hygiene (odds ratio: 1.63, 95% confidence interval: 0.89–2.95). Further, the prevalence of influenza infection was lower in the subjects with saliva weakly acidic and/or containing higher protein level. The results of this study suggested that the maintenance of oral health conditions might be one of the pivotal factors for preventing and reducing influenza infection.

Effectiveness of an Out-of-Pocket Cost Removal Intervention on Health Check Attendance in Japan.

Annual health checks are important for identifying individuals at high risk for cardiometabolic diseases. However, there are socioeconomic disparities in health check attendance rates, and an intervention to lower financial barriers could be useful for increasing health check utilization. In this study, we aimed to evaluate the effectiveness of an out-of-pocket cost removal intervention on health check attendance in Japan. Data were obtained on beneficiaries of the National Health Insurance system of Yokohama City, Kanagawa Prefecture, Japan. In 2018, Yokohama started an intervention to remove out-of-pocket costs for specific health checks for all National Health Insurance beneficiaries. We analyzed data from 2015−2018 (131,295 people aged 40–74 years; 377,660 observations). A generalized estimating equation showed that people were more likely to receive specific health checks in 2018 (after the out-of-pocket cost removal intervention started) than in 2017 (immediately before the intervention; odds ratio [95% confidence interval] = 1.167 [1.149–1.185]), after adjusting for age, gender, tax exemption, and residential area. Stratified analyses revealed that the effectiveness of the out-of-pocket cost removal intervention was greater among the older age group and those who did not receive a tax exemption (i.e., those with relatively higher income). The present study showed that the out-of-pocket cost removal intervention could promote specific health check utilization. This indicates that removing financial barriers could motivate people’s behavior regarding health check attendance.