Association between toothbrushing and risk factors for cardiovascular disease: a large-scale, cross-sectional Japanese study

A Scoping Review of the Relation Between Toothbrushing and Diabetes Knowledge, Glycemic Control, and Oral Health Outcomes in People With Type 2 Diabetes

Objective

Given the bidirectional relationship between type 2 diabetes and periodontal disease, this study sought to compile the available data regarding the relationship between home oral hygiene, specifically toothbrushing, and glycemic control and oral health in people with type 2 diabetes.

Methods

A systematic scoping review was conducted using a combination of controlled vocabulary and keyword terms for type 2 diabetes and home oral care in PubMed and CINHAL. Publications from the past 20 years were considered for inclusion. Study data were summarized.

Results

A total of 11 studies met our inclusion criteria. In all survey research identified, self-report of more frequent toothbrushing in people with type 2 diabetes was always found to be associated with self-report of better glycemic control and was often associated with better clinician-conducted measures oral health. In the interventional studies identified, health coaching about oral health was associated with improvements in glycemic control, and health coaching compared with health education was found to be associated with enhanced improvement in glycemic control and self-reported toothbrushing behavior.

Conclusion

The available data suggest that improved engagement in toothbrushing behavior may be associated with improved oral health and better glycemic control in people with type 2 diabetes. Whether improvement in glycemic control is a direct result of change to the oral environment, succeeding with one behavior change stimulating engagement in other health behavior changes, a combination of the two, or something else cannot be determined from this review. Additional studies are needed to further explore the potential for oral health coaching to improve the well-being of people with type 2 diabetes.

Association between oral health behavior and chronic diseases among middle-aged and older adults in Beijing, China

OBJECTIVES

To evaluate the association between oral health behavior and multiple chronic diseases among middle-aged and older adults.

METHODS

We obtained data of the Beijing Health Service Survey and used multivariate logistic models to estimate the association between oral hygiene behavior and the risk of chronic diseases.

RESULTS

The risk of any chronic diseases (OR = 1.27, 95% CI: 1.18-1.37), cardiovascular diseases (CVD, OR = 1.30, 95% CI: 1.21-1.39), and endocrine or nutritional metabolic disorders (OR = 1.11, 95% CI: 1.01-1.22) was higher in those who with poor oral health behavior. There was no significant correlation between oral health behavior and the risk of diseases of the musculoskeletal, respiratory, digestive, and genitourinary systems.

CONCLUSIONS

Poor oral hygiene practices were associated with higher risk of chronic diseases, CVD and diabetes mellitus (DM) among middle-aged and older adults. These findings motivate further studies to evaluate whether improved oral health behavior may prevent the incidence of chronic diseases.

Association between the interval of worksite dental check-ups and dental and medical expenditures: a single-site, 12-year follow-up study in Japan

OBJECTIVES

The purpose of this study was to identify the effective intervals of worksite dental check-ups to reduce cumulative dental expenditures (CDEs) and cumulative medical expenditures (CMEs), based on 12 years of follow-up dental check-ups.

SETTING, DESIGN AND PARTICIPANTS

A longitudinal study was conducted between 2002 and 2014 fiscal years. A total of 2691 full-time employees (2099 males and 592 females) aged 20-59 years in a manufacturing company in Japan were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Based on the follow-up of 12-year dental check-ups, the interval of dental check-ups visits was classified into the following categories: 'Once per year' as the regular group, 'At least once per 2 years' as the subregular group and others as the irregular group. CDEs and CMEs per capita were examined by the three groups of dental check-ups interval after adjustment for sex, age, occupation and total CMEs at baseline. For sensitivity analysis, decayed teeth, missing teeth and Community Periodontal Index were added as adjustment factors.

RESULTS

Compared with the irregular group, the pooled CDEs (including dental check-ups fee) per capita in the subregular group (OR 0.91, 95% CI 0.85 to 0.98) and regular group (OR 0.87, 95% CI 0.81 to 0.93) were significantly lower overall. The younger adults in the subregular group and younger-aged and middle-aged adults in the regular group had significantly lower CDEs. Sensitivity analysis confirmed these findings.

CONCLUSIONS

Our findings suggest that regular and subregular worksite dental check-ups were related to reduction of CDEs. It is important to promote a yearly interval between dental check-ups.

Meta-analysis on the association between the frequency of tooth brushing and hypertension risk

It is unclear whether the frequency of tooth brushing affects the risk of hypertension; thus, we conducted the first meta-analysis to focus on this topic. In this meta-analysis, we systematically searched the PubMed, Scopus, and Web of Science databases from their inception to October 2021 to identify eligible studies, while reference lists from retrieved review paper were also reviewed. We then conducted a meta-analysis of the highest compared with the lowest tooth brushing frequency, along with a dose-response meta-analysis, to explore this association. Subgroup and sensitivity analyses were conducted to identify the sources of heterogeneity. Publication bias was evaluated using Begg's and Egger's tests. We found eight relevant studies, three cohort and five cross-sectional, involving a total of 274 124 patients. Compared to the highest tooth brushing frequency, the lowest increased the risk of hypertension by 84.0% (OR 1.84; 95% CI, 1.44-2.35). Furthermore, a nonlinear dose-response relationship was observed (P < .05). The exclusion of any studies did not significantly alter the combined risk estimate, and no publication bias was detected. In conclusions, we report that epidemiological evidence supports the hypothesis that a lower frequency of tooth brushing is significantly associated with a higher risk of hypertension. Preventive interventions, such as adopting a good oral health routine, should be encouraged to maintain good general health.

Associations of oral hygiene with incident hypertension and type 2 diabetes mellitus: A population based cohort study in Southwest China

Oral health has been previously reported to be related with cardiovascular diseases (CVD). This study aimed to evaluate whether oral hygiene could reduce the risk of incident hypertension and type 2 diabetes mellitus (T2DM) in a population-based cohort. A total of 9280 people aged 18 years or above in Guizhou province were recruited from November 20th, 2010 to December 19th, 2012. Sociodemographic characteristics, lifestyles, anthropometric measurements, oral health status and care were collected by trained interviewers. The occurrences of hypertension and T2DM were ascertained until 2020. Cox proportional hazard models were used to evaluate the associations between oral hygiene and the occurrence of hypertension and T2DM, respectively. Compared with almost no tooth brushing, tooth brushing at least twice a day was associated with a 45% reduction (HR: .55; 95% CI: .42-.73) in hypertension events and reduced diabetes risk by 35% (HR: .65; 95% CI: .45-.94). For hypertension, those associations tended to be more pronounced in participants with Han ethic, or living in urban area, while those aged less than 60 or without baseline hypertension were more likely to have T2DM when they brush teeth less than twice a day. Frequent tooth brushing was associated with reduced risks of incident hypertension and T2DM. Tooth brushing at least twice a day may prevent future hypertension and T2DM events.

A Correlation Study of the Microbiota Between Oral Cavity and Tonsils in Children With Tonsillar Hypertrophy

Tonsillar hypertrophy is a common disease in 3-to-6-year-old children, which may cause serve symptoms like airway obstruction. Microbiological factors play an important role in the etiology of tonsillar hypertrophy. As the starting point of digestive and respiratory tracts, the microbial composition of the oral cavity is not only unique but also closely related to the resident microbiota in other body sites. Here we reported a correlation study of the microbiota between oral cavity and tonsils in children with tonsillar hypertrophy. Saliva, supragingival plaque, and wiped samples from the tonsil surface were collected from both tonsillar hypertrophy patients and participants with healthy tonsils and were then analyzed using Illumina Miseq Sequencing of the 16S rRNA gene. In the tonsillar hypertrophic state, more genera were detected on the tonsil surface than in the tonsil parenchyma, with more intra-microbiota correlations. When tonsillar hypertrophy occurred, both the oral cavity and tonsil surface endured microbiome shift with increased genera category and more active bacterial interactions. Over half of the newly detected genera from the tonsillar hypertrophic state were associated with infection and inflammation process or exhibited antibiotic-resistant characters. Of each individual, the microbial composition and structure of saliva seemed more similar to that of the tonsil surface, compared with the supragingival plaque. In salivary microbiota, genus Johnsonella might be relative with the healthy state of tonsils, while Pseudoxanthomonas might be relative with tonsillar hypertrophy. Our study supported the link between oral microbiota with the healthy and hypertrophic states of tonsils and may provide new directions for future researches in the specific role of oral microbiota in the etiology of tonsil diseases.

Association between Frequency of Toothbrushing and Metabolic Syndrome among Adolescents: A 5-Year Follow-Up Study

This study longitudinally examines the relationship between the frequency of toothbrushing and the development of selected components of metabolic syndrome (MetS), along with the potential role of salivary biomarkers in this relationship. In 2014, 6317 12-year-old children underwent health examinations (T1), of which, 348 children participated in the second stage of data collection in 2019 (T2). The association between the change in the metabolic status during the 5-year follow-up examination (between T1 and T2) and frequency of toothbrushing was assessed using multinomial logistic regression analyses. At T2, healthy adolescents had significantly higher odds of toothbrushing twice or more daily compared with adolescents with components of MetS (OR = 1.99, 95% CI 1.15-3.45). Adolescents who were healthy at T1 but developed components of MetS at T2, had significantly higher frequencies of dining-out compared with adolescents with components of MetS at both T1 and T2 (OR = 0.09, 95% CI 0.02 to 0.49). Adolescents who were 'healthy' at both T1 and T2 had significantly (p < 0.05) lower levels of C-reactive protein (T2), insulin (T1 and T2), interleukin-6 (T1) and adiponectin (T1) compared with adolescents who had components of MetS. Toothbrushing and frequency of dining-out were associated with the presence of MetS components.

Associations of toothbrushing behaviour with risks of vascular and nonvascular diseases in Chinese adults

Accumulating evidence has shown that poor oral hygiene is associated with increased risk of cardiometabolic diseases in Western populations. However, its relevance about the relationships in Chinese adults remains unclear. The China Kadoorie Biobank enrolled 512 715 adults aged 30-79 years in China during 2004-2008. Cox regression was used to estimate adjusted hazard ratios (HRs) for each disease associated with measures of oral hygiene. Overall 9.3% of the participants reported rarely or never brushing teeth at baseline. Participants who rarely or never brushed teeth had adjusted HR of 1.12 (95% CI: 1.09, 1.15) for MVE, with similar HRs for stroke (1.08, 1.05-1.12), intracerebral haemorrhage (1.18, 1.11-1.26) and pulmonary heart disease (1.22, 1.13-1.32) compared with those who brushed teeth regularly. Those who did not brush teeth also had increased risk of cancer (1.09, 1.04-1.14), chronic obstructive pulmonary disease (COPD) (1.12, 1.05-1.20), liver cirrhosis (1.25, 1.09-1.44) and all-cause death (1.25, 1.21-1.28) but not type 2 diabetes (0.94, 0.86-1.03) and chronic kidney disease (0.98, 0.81-1.18). Among Chinese adults, we found that poor oral hygiene is associated with higher risks of major vascular disease, cancer, COPD, liver cirrhosis and all-cause deaths, but not type 2 diabetes and chronic kidney disease.

Health Behaviors and Self-Reported Oral Health among Centenarians in Nanjing, China: A Cross-Sectional Study

The role of health behaviors in oral health conditions in individuals of extremely old age remains understudied. This study included 185 participants aged 100 years or older from the Nanjing Centenarians Study (NCS) to examine the associations between health behaviors and oral health and investigate the potential moderating role of education and living arrangements in such relationships. The oral health status as an outcome included the self-reported oral health status and edentulous status. Health behavior variables included smoking, eating fruits, eating vegetables, participating in leisure activities, and practicing oral hygiene behaviors. Sociodemographic characteristics and health status were considered as confounders. Descriptive statistics, ordinal regression, and logistic regression models were used to address the research questions. Results showed that better oral health was reported by centenarians who were non-smokers, participated in more leisure activities, and practiced higher frequency of oral hygiene behaviors. Those who ate fruits daily and practiced more frequently oral hygiene behaviors were more likely to be dentate. The positive association of oral hygiene behaviors was stronger for centenarians who were formally educated and co-resided with family members. The results suggest that effective interventions should consider health behaviors and living arrangements in this growing population to improve their oral health status.

Frequency of tooth brushing as a predictive factor for future kidney function decline

BACKGROUND

Tooth brushing is important for maintaining oral health and preventing periodontal diseases (PDs), which commonly arise in patients with chronic kidney disease (CKD). However, the association between tooth brushing frequency and kidney function decline remains unclear.

METHODS

We conducted a retrospective longitudinal study at St Luke's International Hospital, Japan, and participants who underwent health examinations at the Centre for Preventive Medicine from 2005 to 2011 were included. Participants' tooth brushing frequencies were assessed; multivariate analyses were conducted using a generalized estimating equation to evaluate the association between tooth brushing frequency and a composite renal outcome-composed of a 25% estimated glomerular filtration rate (eGFR) reduction, an eGFR of < 15 mL/min/1.73 m², and a requirement for regular dialysis-after adjusting for potential covariates. We also stratified participants by baseline CKD risk category to perform sub-analyses.

RESULTS

Overall, 76,472 participants were included (mean age of 45.9 years) and 38,233 (50%) were male. During follow-up, 8219 participants (10.8%) experienced composite renal outcomes. Brushing teeth at least once to twice a day was associated with significantly lower incidences of composite renal outcomes than brushing teeth less frequently (adjusted odds ratio [OR] 0.26; 95% confidence interval [CI] 0.24-0.28 for once to twice a day; adjusted OR 0.65; 95% CI 0.62-0.69 for after every meal). In our sub-analyses, brushing at least once to twice a day related to a decreased likelihood of composite renal outcomes; however, this effect was only observed within the low and moderate baseline risk groups.

CONCLUSION

Frequent tooth brushing benefits oral health and may be associated with slower kidney function decline, which could have implications for other systemic diseases. However, a longitudinal cohort study is required to confirm whether tooth brushing and overall oral health can haver a role in improving  renal outcomes.

The Optimal Range of Serum Uric Acid for Cardiometabolic Diseases: A 5-Year Japanese Cohort Study

The optimal range of serum uric acid (urate) associated with the lowest risk for developing cardiometabolic diseases is unknown in a generally healthy population. This 5-year cohort study is designed to identify the optimal range of serum urate. The data were collected from 13,070 Japanese between ages 30 and 85 at the baseline (2004) from the Center for Preventive Medicine, St. Luke’s International Hospital, Tokyo. We evaluated the number of subjects (and prevalence) of those free of the following conditions: hypertension, diabetes, dyslipidemia, and chronic kidney disease (CKD) over 5 years for each 1 mg/dL of serum urate stratified by sex. Furthermore, the odds ratios (ORs) for remaining free of these conditions were calculated with multiple adjustments. Except for truly hypouricemic subjects, having lower serum urate was an independent factor for predicting the absence of hypertension, dyslipidemia, and CKD, but not diabetes. The OR of each 1 mg/dL serum urate decrease as a protective factor for hypertension, dyslipidemia, and CKD was 1.153 (95% confidence interval, 1.068–1.245), 1.164 (1.077–1.258), and 1.226 (1.152–1.306) in men; 1.306 (1.169–1.459), 1.121 (1.022–1.230), and 1.424 (1.311–1.547) in women, respectively. Moreover, comparing serum urate of 3–5 mg/dL in men and 2–4 mg/dL in women, hypouricemia could be a higher risk for developing hypertension (OR: 4.532; 0.943–21.78) and CKD (OR: 4.052; 1.181–13.90) in women, but not in men. The optimal serum urate range associated with the lowest development of cardiometabolic diseases was less than 5 mg/dL for men and 2–4 mg/dL for women, respectively.

Prevalence of altered total cholesterol and fractions in the Brazilian adult population: National Health Survey

OBJECTIVE

To analyze the prevalence of altered total cholesterol and fractions levels in the Brazilian population, according to biochemical data from the National Health Survey.

METHODS

A descriptive study, using data from the National Health Survey, collected between 2014 and 2015. Total cholesterol and fractions were analyzed and population prevalences of altered values according to socio-demographic variables were calculated. The cutoff points considered were: total cholesterol ≥ 200mg/dl; low-density lipoprotein LDL ≥ 130mg/dL and high-density lipoprotein HDL < 40mg/dL.

RESULTS

The prevalence of total cholesterol ≥200mg/dL in the population was 32.7%, and higher in women (35.1%). The prevalence of altered HDL was 31.8%, 22.0% in females and 42.8% in males. LDL ≥ 130mg/dL was found in 18.6% and was higher in women (19.9%). The population aged 45 years old and older and those with low levels of education presented a higher prevalence of altered cholesterol.

CONCLUSION

Altered values of total cholesterol and fractions were frequent in the Brazilian population, especially among women, the elderly and people with low levels of education. These results may guide control and preventative actions such as healthy eating, physical activity and treatment, all of which aim to prevent coronary diseases.

Oral health of high-cost patients and evaluation of oral health measures as predictors for high-cost patients in South Korea: a population-based cohort study

OBJECTIVE

To examine the oral health conditions and oral health behaviour of high-cost patients and evaluate oral health measures as predictors of future high-cost patients.

DESIGN

A retrospective, population-based cohort study using administrative healthcare records.

SETTING

The National Health Insurance Service (NHIS) medical check-up database (a.k.a. NHIS-national health screening cohort database) in South Korea.

PARTICIPANTS

131 549 individuals who received biennial health check-ups including dental check-ups in 2011 or 2012, aged 49-88.

PRIMARY OUTCOME MEASURES

Current and subsequent year high-cost patient status.

RESULTS

High-cost patients, on average, incur higher dental costs, suffer more from periodontal disease, brush their teeth less and use secondary oral hygiene products less. Some of the self-reported oral health behaviours and oral symptom variables show statistically significant associations with subsequent year high-cost patient indicators, even after adjusting for demographic, socioeconomic, medical conditions, and prior healthcare cost and utilisation.

CONCLUSIONS

We demonstrate that oral health measures are associated with an increased risk of becoming a high-cost patient.

Meta-analysis on the association between the frequency of tooth brushing and diabetes mellitus risk

BACKGROUND AND OBJECTIVE

Epidemiological studies suggested that the frequency of tooth brushing might be associated with the risk of diabetes mellitus (DM), but the results were inconsistent, and no systematic review was conducted to focus on this topic. In this meta-analysis, we synthesized available observational epidemiological evidences to identify the association between tooth brushing and DM risk and investigate the potential dose-response relationship of them.

METHODS

We searched PubMed and Embase from their inception through December 2017 to identify observational studies examining the association between tooth brushing and the risk of DM. Reference lists from retrieved articles were also reviewed. We quantitatively combined results of the included studies using a random-effects model. Dose-response meta-analysis was conducted to further examine the effect of tooth brushing frequency on DM risk.

RESULTS

We identified 20 relevant studies (one cohort study, 14 case-control studies, and 5 cross-sectional studies) involving 161 189 participants and 10 884 patients with DM. Compared with the highest tooth brushing frequency, the lowest level was significantly associated with an increased risk of DM (OR 1.32; 95% CI, 1.19-1.47), and there was no significant heterogeneity across the included studies (p = 0.119, I²  = 28.1%). Exclusion of any single study did not materially alter the combined risk estimate. The dose-response analysis indicated that the summary odds of DM for an increment of one time of tooth brushing per day was 1.20 (95% CI, 1.16-1.24).

CONCLUSIONS

Integrated epidemiological evidence supports the hypothesis that low frequency of tooth brushing may be a risk factor of DM, and lower frequencies of tooth brushing were significantly associated with higher risk of DM.

Association Between Toothbrushing and Behavioral Risk Factors of Non-communicable Diseases: A population Based Survey of 4500 adults in China

Non-communicable Disease (NCD) related behavioral risk factors (BRF) plays a crucial role in NCD prevention, as does oral hygiene behavior in oral health promotion. We examined the association between NCD BRF and toothbrushing using data from a population-based survey, which recruited 4485 adults aged 18+ years, in Chongqing city, China. Prevalence of five NDC BRF and their clustering within individual were determined by toothbrushing frequency. Ordinal logistic regression examined the association between toothbrushing and BRF clustering. Prevalence of current smoking, insufficient intake of vegetable and fruit, and harmful use of alcohol increased significantly with toothbrushing frequency. Respondents who brushed teeth ≥2 times daily consumed more red meat than those with less frequent toothbrushing. Relative to those with no BRF, the adjusted cumulative odds ratio of brushing teeth less frequently was 2.1 (95% CI: 1.4-3.1) for respondents with 3+ BRF. The adjusted cumulative odds ratio was 1.5 (1.1-2.1) and 1.4 (1.0-1.8) for those who had two BRF and those who had one, respectively. Significant correlation between toothbrushing and NCD BRF implied that integrated intervention strategy involving the both may be beneficial in public health programs targeting at either oral health or NCDs, or both.

High rate of calories from protein is associated with higher prevalence of hypertension

The desirable distribution of three major nutrients intake to prevent hypertension is not established. This study is to clarify the relationship between the prevalence of hypertension and the rate of intake of three major nutrients. This is a large-scale cross-sectional study. We analyzed Japanese subjects who had their annual medical examination at St Luke's International Hospital, Tokyo from January 2004 to June 2010. The amount of three major nutrients and salt intake were checked by a questionnaire method, and this study clarified the relationship between the prevalence of hypertension and the rate of three major nutrients with adjustment for age, sex, body mass index (BMI), smoking, dyslipidemia, diabetes mellitus, hyperuricemia, and salt intake. We analyzed 89,851 subjects. Of those, the number of hypertensive subjects was 13,926 (15.5%). The hypertensive group had significantly higher rate of calories from protein (19.7% vs. 19.4%, P < 0.001) but lower rate of calories from fat (16.1% vs. 16.4%, P < 0.001) than that in the non-hypertensive group. The rate of calories from carbohydrate was almost the same between the two groups (64.2% vs. 64.2%). After multiple adjustments, high rate of calories from protein was associated with high prevalence of hypertension (odds ratio: 1.011, 95% confidence interval (CI), 1.005-1.017), as well as aging, male, high BMI, smoking habits, dyslipidemia, diabetes mellitus, and hyperuricemia. High rate of calories from protein could be associated with high risk of hypertension. Therefore, protein-restricted diet may have a favorable effect in preventing hypertension and cardiovascular diseases.

The oral health status, behaviours and knowledge of patients with cardiovascular disease in Sydney Australia: a cross-sectional survey

BACKGROUND

Periodontal disease is a risk factor for atherosclerotic cardiovascular disease and it is recommended internationally that patients with cardiovascular disease should engage in preventative oral health practices and attend regular dental care visits. This study aimed to explore the oral health status, behaviours and knowledge of patients with cardiovascular disease.

METHODS

A cross-sectional questionnaire containing 31 items was administered to patients with cardiovascular disease from cardiac rehabilitation and outpatient clinics in Sydney Australia in 2016-2017.

RESULTS

Of the 318 patients surveyed, 81.1% reported having at least one oral health problem. Over a third (41.2%) of participants had not seen a dentist in the preceding 12 months and 10.7% had received any oral healthcare information in the cardiac setting. Those with valvular conditions were more likely to have received information compared to those with other cardiovascular conditions (40.6% versus 7.4%, p < 0.001). Only half of the participants had adequate oral health knowledge.

CONCLUSIONS

Despite a high incidence of reported oral health problems, many patients lacked knowledge about oral health, were not receiving oral health information from cardiac care providers and had difficulty accessing dental services. Further research is needed to develop oral health strategies in this area.

Different Risk for Hypertension, Diabetes, Dyslipidemia, and Hyperuricemia According to Level of Body Mass Index in Japanese and American Subjects

Obesity is a risk factor for hypertension, diabetes mellitus (DM), dyslipidemia, and hyperuricemia. Here, we evaluated whether the same body mass index (BMI) for the U.S. population conferred similar metabolic risk in Japan. This was a cross-sectional analysis involving 90,047 Japanese adults (18⁻85 years) from St. Luke's International Hospital, Tokyo, Japan and 14,734 adults from National Health and Nutrition Examination Survey (NHANES) collected in the U.S. We compared the prevalence of hypertension, DM, dyslipidemia, and hyperuricemia according to BMI in Japan and the U.S. The prevalence of hypertension, DM, and dyslipidemia were significantly higher in the U.S. than Japan, whereas the prevalence of hyperuricemia did not differ between countries. Higher BMI was an independent risk factor for hypertension, DM, dyslipidemia, and hyperuricemia both in Japan and in the U.S. after adjusting for age, sex, smoking and drinking habits, chronic kidney disease, and other cardiovascular risk factors. The BMI cut-off above which the prevalence of these cardio-metabolic risk factors increased was significantly higher in the U.S. than in Japan (27 vs. 23 kg/m² for hypertension, 29 vs. 23 kg/m² for DM, 26 vs. 22 kg/m² for dyslipidemia, and 27 vs. 23 kg/m² for hyperuricemia). Higher BMI is associated with an increased prevalence of hypertension, DM, dyslipidemia, and hyperuricemia both in Japan and U.S. The BMI cut-off above which the prevalence of cardio-metabolic risk factors increases is significantly lower in Japan than the U.S., suggesting that the same definition of overweight/obesity may not be similarly applicable in both countries.

"Metabolically Healthy" Obesity and Hyperuricemia Increase Risk for Hypertension and Diabetes: 5-year Japanese Cohort Study

OBJECTIVE

Whether obesity without metabolic syndrome (i.e., "metabolically healthy" obesity) confers similar or less metabolic risk remains controversial.

METHODS

A retrospective 5-year cohort study of 9,721 Japanese subjects (48.5 ± 10.5 years, 4,160 men) was conducted in 2004 and reevaluated 5 years later. Subjects were excluded if they were hypertensive or diabetic or were receiving medications for dyslipidemia and/or gout or hyperuricemia in 2004. Study subjects were categorized according to baseline BMI  ≥ 25 kg/m² (overweight/obesity) and < 25 kg/m² (lean/normal weight) and also whether they had metabolic syndrome. The cumulative incidence of hypertension and diabetes over 5 years between groups was assessed. A second analysis evaluated whether baseline hyperuricemia provided additional risk.

RESULTS

Subjects with overweight/obesity but without metabolic syndrome carried increased cumulative incidence of hypertension (14.6% vs. 7.2%, P < 0.001) and diabetes (2.6% vs. 1.1%, P = 0.004) over 5 years compared to lean/normal subjects without metabolic syndrome. Overweight/obesity conferred an increased risk for diabetes even in individuals with normal fasting blood glucose. Hyperuricemia became an independent risk factor for developing hypertension over 5 years in lean/normal subjects without metabolic syndrome. A 1 mg/dL increase in serum uric acid carried increased risk for hypertension (19%) and diabetes (27%).

CONCLUSIONS

Metabolically healthy obesity and hyperuricemia confer increased risk for hypertension and diabetes.

Prevalence and complications of hypouricemia in a general population: A large-scale cross-sectional study in Japan

BACKGROUNDS

Hypouricemia was reported as a risk factor for exercise-induced acute renal injury (EIAKI) and urinary stones. However, the prevalence of kidney diseases among hypouricemic subjects has not been evaluated. This study was conducted to clarify the prevalence of hypouricemia and the association of hypouricemia with kidney diseases by using a large-scale Japanese population data.

METHODS

This study is a retrospective cross-sectional study at the Center for Preventive Medicine, St. Luke's International Hospital, Tokyo, Japan, and Sanin Rousai Hospital, Yonago, Japan. We analyzed the medical records of 90,143 Japanese subjects at the center in St. Luke's International Hospital, Tokyo, and 4,837 subjects in Sanin Rousai Hospital, Yonago, who underwent annual regular health check-up between January 2004 and June 2010. We defined hypouricemia as serum uric acid level of ≤2.0 mg/dL. We checked the medical history of all the study subjects and compared the rates of complications including urinary stones and kidney diseases among those with or without hypouricemia.

RESULTS

The prevalence of hypouricemia was 0.19% in St. Luke's International Hospital, Tokyo, and 0.58% in Sanin Rousai Hospital, Yonago. The prevalence of hypouricemia in women was larger than that in men both in Tokyo (0.31% vs 0.068%, p<0.001) and in Yonago (1.237% vs 0.318%, p<0.001). Among 172 hypouricemic subjects (30 men), the rates of previous urinary stones and kidney diseases (including nephritis/nephrosis) were 1.2% (3.3% men, 0.7% women) and 2.3% (10% men, 0.7% women), respectively. Hypouricemic men had a 9-fold higher rate of previously having kidney diseases compared to non-hypouricemic men (p<0.001). However, the rates of other diseases including urinary stones were not significantly different between the two groups.

CONCLUSIONS

Hypouricemia was associated with a history of kidney disease especially in men.

Asymptomatic Hyperuricemia Without Comorbidities Predicts Cardiometabolic Diseases: Five-Year Japanese Cohort Study

Whether asymptomatic hyperuricemia in the absence of comorbidities increases the risk for cardiometabolic disorders and chronic kidney disease remains controversial. This study was conducted to clarify the association between asymptomatic hyperuricemia and cardiometabolic conditions. Subjects consisting of Japanese adults between 30 and 85 years of age were enrolled in the study at Center for Preventive Medicine, St Luke's International Hospital, Tokyo, and were available at enrollment (2004) and at 5-year follow-up (2009). Subjects were excluded if they were overweight or obese, hypertensive, diabetic, and dyslipidemic, had a history of gout or hyperuricemia on medications, or had chronic kidney disease as estimated glomerular filtration rate <60 mL/min per 1.73 m² Linear and logistic regression analyses were used to examine the relationship between hyperuricemia and development of hypertension, diabetes mellitus, dyslipidemia, chronic kidney disease, and overweight/obesity (unadjusted and adjusted for age, sex, smoking, drinking habits, baseline estimated glomerular filtration rate, and body mass index). Five thousand eight hundred and ninety-nine subjects without comorbidities (mean age of 47±10 years, 1864 men) were followed for 5 years. Hyperuricemia (defined as >7 mg/dL in men and ≥6 mg/dL in women) was associated with increased cumulative incidence of hypertension (14.9% versus 6.1%; P<0.001), dyslipidemia (23.1% versus 15.5%; P<0.001), chronic kidney disease (19.0% versus 10.7%; P<0.001), and overweight/obesity (8.9% versus 3.0%; P<0.001), while diabetes mellitus (1.7% versus 0.9%; P=0.087) showed a trend but did not reach statistical significance. In conclusion, asymptomatic hyperuricemia carries a significant risk for developing cardiometabolic conditions in Japanese individual without comorbidities.

Low frequency of toothbrushing practices is an independent risk factor for diabetes mellitus in male and dyslipidemia in female: A large-scale, 5-year cohort study in Japan

BACKGROUND

We previously reported the association between toothbrushing practices and diabetes mellitus (DM) and dyslipidemia (DL) in a cross-sectional study. This study was conducted to clarify whether low frequency of toothbrushing practices is an independent risk factor for DM and DL using a follow-up design.

METHODS

This study was a 5-year retrospective cohort study at St. Luke's International Hospital, Tokyo, Japan. We analyzed study subjects between 30 and 85 years old in 2004, who underwent annual medical examination both in 2004 and 2009. We compared the cumulative incidences of developing DM, DL, hypertension (HT), and hyperuricemia (HUA) between 2004 and 2009 among 3 groups: toothbrushing practices 'after every meal,' 'at least once a day,' and 'less than once a day'. Furthermore, we analyzed odds ratios (ORs) of risk for developing DM and DL by sex after making adjustments for age, obesity, DM, DL, HT, and HUA between two groups: 'after every meal' and 'not after every meal.'

RESULTS

The number of study subjects was 13,070. Of 13,070 study subjects, 575 had DM, 5118 had DL, 2599 had HT, and 1908 had HUA in 2004. We excluded the subjects with each disease in 2004. The cumulative incidences (rates) of DM, DL, HT, and HUA between 2004 and 2009 were 318 (2.5%), 1454 (18.3%), 1108 (10.6%), and 489 (4.4%), respectively. Toothbrushing practices 'not after every meal' was a significant risk factor for developing DM in male [OR: 1.43; 95% confidence interval (CI), 1.040-1.970] and developing DL in female (OR: 1.18; 95% CI, 1.004-1.383) compared with toothbrushing practices 'after every meal.'

CONCLUSION

Toothbrushing practices 'after every meal' prevented developing DM in males and DL in females significantly. Toothbrushing practices may be beneficial to reduce developing risk factors for cardiovascular disease.