Journal of Epidemiology最新文献

Background: Several studies reported an association between the number of teeth and the incidence of hip fractures in observational studies, mainly in middle-aged adults. This retrospective cohort study aimed to clarify the association between the number of teeth and the incidence of hip fractures.

Methods: In this retrospective cohort study, a total of 256,772 participants aged 75 years or older who underwent public dental checkups in Japan were evaluated. Exposure in this study was the number of teeth, with a maximum number of 28, excluding third molars. Outcome measures were the incidence of hip fractures needing surgery, using the Japanese procedure codes in medical claims.

Results: A total of 190,998 participants met the inclusion criteria and were available for analysis. Adjusted Fine and Gray models identified a significant association between the number of teeth, including sound, filled, and decayed teeth, and the incidence of hip fractures among women but not for men. The continuous net reclassification improvement (NRI) of the sound and filled teeth count model increased by 0.078 compared with that of the sound, filled, and decayed teeth count model among women.

Conclusions: The number of sound and filled teeth predicted the risk of hip fractures in women, whereas no association was observed between the number of teeth and hip fractures in men.

Background: Healthy life expectancy (HLE) is a population health indicator that is widely used in developed countries, but little is known about its relationships with combinations of non-communicable disease risk factors. This study was conducted to examine HLE at age 65 according to combinations of blood pressure levels, body mass index, smoking status, and diabetes mellitus (DM) in a Japanese population.

Methods: In a nationwide cohort study (NIPPON DATA90), data on these risk factors were obtained from participants in 1990 through physical examinations, blood tests, interviews, and questionnaires. Subsequently, participants aged ≥65 years underwent surveys on activities of daily living in 1995 and 2000, and multistate life tables were used to calculate combination-specific HLEs and their 95% confidence intervals (CIs).

Results: The study population comprised 6,569 participants (men: 2,797; women: 3,772) who were followed-up until 2010. HLE at age 65 in men with grade II/III hypertension, obesity, current smoker status, and DM (HLE: 12.9 years, 95% CIs: 12.9-13.0 years) was 9.7 years shorter than men without these risk factors (HLE: 22.6 years, 95% CIs: 22.4-22.8 years). Similarly, HLE at age 65 in women with grade II/III hypertension, obesity, current smoker status, and DM (HLE: 16.2 years, 95% CIs: 15.9-16.5 years) was 10.1 years shorter than women without these risk factors (HLE: 26.3 years, 95% CIs: 26.3-26.3 years).

Conclusion: The large discrepancies in HLEs underscore the impact of non-communicable disease risk factors, which should be considered when formulating health interventions to improve HLE in Japanese older adults.

Introduction: Relative or absolute safety of heated tobacco products (HTP) remains unknown, while independent literature suggests that these products do not favour tobacco control. We conducted a comprehensive systematic review and meta-analysis to evaluate HTP usage patterns and the effect of HTP use on conventional tobacco smoking (use transitions).

Methods: We used Pubmed/MEDLINE, Embase and the Cochrane Library to identify all articles published up to February 2022 on HTP use. For the present review, we included all representative cross-sectional studies dealing with HTP use, and all prospective cohort studies or cross-sectional studies on conventional tobacco smoking transitions due to HTP use. From 610 non-duplicate articles, 76 were eligible (71 cross-sectional and 5 prospective cohort studies).

Results: Compared with young adults, HTP use was less frequent among middle-aged (pooled odds ratio, OR=0.59; 95% confidence interval, CI: 0.48-0.74; number of studies, n=15) and older adults (OR=0.17; 95%-CI: 0.07-0.38; n=12). HTP use was more frequent among former (OR=2.73; 95%-CI: 1.03-7.25; n=6) and current smokers (OR=14.53; 95%-CI: 6.34-33.31; n=12). Overall, 68.3% of HTP users were dual users (n=26). Eight studies (including 5 cohorts) showed that HTP users were more likely than non-users to start conventional cigarette smoking (OR=6.31; 95%-CI: 4.13-9.65; n=2), whereas current cigarette smokers using HTPs were less likely to quit (OR=0.84; 95%-CI: 0.80-0.89; n=4).

Conclusions: We found that HTPs are specifically popular among young generations. More than two out of three HTP users are dual users. Prospective studies consistently show that in real life HTPs are not effective smoking cessation tools.

Background: The participation rate for screening is regarded as a useful indicator for preventing cancer and cardio-metabolic disease. However, the validity of self-reported screening participation has not yet been thoroughly evaluated in Japan. We aimed to examine its validity using the municipal screening records among the Japanese population.

Methods: We included 3,060 men and 3,860 women insured by the National Health Insurance for residents aged <75 years or the Medical Care System for the Elderly aged ≥75 years in the Chikusei area of the Japan Public Health Center-based Prospective Study for the Next Generation. They were asked about their participation in cancer screenings and health checkups during the previous year. We compared their responses to the municipal records and calculated the sensitivity and specificity of self-reported screening participation.

Results: The sensitivity and specificity of self-reported participation were 0.49 and 0.86 for lung cancer screening, 0.67 and 0.85 for colorectal cancer screening, 0.77 and 0.79 for stomach cancer screening, and 0.86 and 0.65 for health checkup, respectively. Among women, the sensitivity and specificity were 0.83 and 0.81 for breast cancer and 0.85 and 0.90 for cervical cancer, respectively.

Conclusion: Self-reported cancer screening participation for colorectal, stomach, breast, and cervical cancers had moderate-to-high sensitivity and specificity. Self-reported participation, especially for lung cancer screening and health checkups, should be carefully interpreted when assessing the performance of preventive measures.

Background: Dementia is the leading cause of disability and imposes a significant burden on society. Previous studies have suggested an association between metabolites and cognitive decline. Although the metabolite composition differs between Western and Asian populations, studies targeting Asian populations remain scarce.

Methods: This cross-sectional study used data from a cohort survey of community-dwelling older adults aged ≥60 years living in Miyagi, Japan, conducted by Tohoku Medical Megabank Organization between 2013 and 2016. Forty-three metabolite variables quantified using nuclear magnetic resonance spectroscopy were used as explanatory variables. Dependent variable was the presence of cognitive decline (≤23 points), assessed by the Mini-Mental State Examination. Principal component (PC) analysis was performed to reduce the dimensionality of metabolite variables, followed by logistic regression analysis to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for cognitive decline.

Results: A total of 2,940 participants were included (men: 49.0%, mean age: 67.6 years). Among them, 1.9% showed cognitive decline. The first 12 PC components (PC1-PC12) accounted for 71.7% of the total variance. Multivariate analysis showed that PC1, which mainly represented essential amino acids, was associated with lower odds of cognitive decline (OR 0.89; 95% CI, 0.80-0.98). PC2, which mainly included ketone bodies, was associated with cognitive decline (OR 1.29; 95% CI, 1.11-1.51). PC3, which included amino acids, was associated with lower odds of cognitive decline (OR 0.81; 95% CI, 0.66-0.99).

Conclusion: Amino acids are protectively associated with cognitive decline, whereas ketone metabolites are associated with higher odds of cognitive decline.

Background: Individuals with type 2 diabetes mellitus (T2DM) have increased colorectal cancer (CRC) risk, but it is unknown whether income dynamics are associated with CRC risk in these individuals. We examined whether persistent low- or high-income and income changes are associated with CRC risk in non-elderly adults with T2DM.

Methods: Using nationally representative data from the Korean Health Insurance Service database, 1,909,492 adults aged 30 to 64 years with T2DM and no history of cancer were included between 2009 and 2012 (median follow-up of 7.8 years). We determined income levels based on health insurance premiums and assessed annual income quartiles for the baseline year and the four preceding years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated after adjusting for sociodemographic factors, CRC risk factors, and diabetes duration and treatment.

Results: Persistent low income (ie, lowest income quartile) was associated with increased CRC risk (HR_{5 years vs 0 years} 1.11; 95% CI, 1.04-1.18; P for trend = 0.004). Income declines (ie, a decrease ≥25% in income quantile) were also associated with increased CRC risk (HR_{≥2 vs 0 declines} 1.10; 95% CI, 1.05-1.16; P for trend = 0.001). In contrast, persistent high income (ie, highest income quartile) was associated with decreased CRC risk (HR_{5 years vs 0 years} 0.81; 95% CI, 0.73-0.89; P for trend < 0.0001), which was more pronounced for rectal cancer (HR 0.64; 95% CI, 0.53-0.78) and distal colon cancer (HR 0.70; 95% CI, 0.57-0.86).

Conclusion: Our findings underscore the need for increased public policy awareness of the association between income dynamics and CRC risk in adults with T2DM.

In observational studies, identifying and adjusting for a sufficient set of confounders is crucial for accurately estimating the causal effect of the exposure on the outcome. Even in studies with large sample sizes, which typically benefit from small variances in estimates, there is a risk of producing estimates that are precisely inaccurate if the study suffers from systematic errors or biases, including confounding bias. To date, several approaches have been developed for selecting confounders. In this article, we first summarize the epidemiological and statistical approaches to identifying a sufficient set of confounders. Particularly, we introduce the modified disjunctive cause criterion as one of the most useful approaches, which involves controlling for any pre-exposure covariate that affects the exposure, outcome, or both. It then excludes instrumental variables but includes proxies for the shared common cause of exposure and outcome. Statistical confounder selection is also useful when dealing with a large number of covariates, even in studies with small sample sizes. After introducing several approaches, we discuss some pitfalls and considerations in confounder selection, such as the adjustment for instrumental variables, intermediate variables, and baseline outcome variables. Lastly, as it is often difficult to comprehensively measure key confounders, we introduce two statistics, E-value and robustness value, for assessing sensitivity to unmeasured confounders. Illustrated examples are provided using the National Health and Nutritional Examination Survey Epidemiologic Follow-up Study. Integrating these principles and approaches will enhance our understanding of confounder selection and facilitate better reporting and interpretation of future epidemiological studies.

Background: Community social capital is associated with various health outcomes; however, its impact on mortality is not fully understood, particularly in non-Western settings. This study examined the association between community-level social capital and all-cause mortality among community-dwelling older Japanese adults.

Methods: The baseline data were obtained from a 2015 questionnaire survey for all 132,005 residents aged ≥65 years without long-term care insurance certification in Adachi Ward (consisting of 262 small districts) of the Tokyo metropolitan area. We measured two aspects of social capital: neighborhood cohesion as cognitive social capital and neighborhood network as structural social capital. For district-level social capital, we aggregated the individual responses of neighborhood cohesion and neighborhood network in each district.

Results: A total of 75,338 were analyzed. A multilevel survival analysis with an average follow-up of 1,656 days showed that higher district-level neighborhood cohesion was associated with a lower risk of all-cause mortality in men (hazard ratio [95% confidence interval]: 0.92 [0.84-0.99] for the highest quintile and 0.91 [0.82-0.99] for the second, compared to the lowest), not in women. This association was more pronounced in men aged 65-74 years.

Conclusions: This study provides valuable insights from the Asian population. Men, who typically have fewer social networks and support systems than women, could receive more benefits from residing in a cohesive community, which may contribute to their longevity. These findings support public health strategies that bolster community social capital as a means of archiving longevity among older men, underscoring the importance of social integration in aging societies.