Mortality In Japan Research Articles

Short-term association between ambient temperature and renal disease mortality in Japan from 1979 to 2019: a time-stratified case-crossover analysis

Short-term association between ambient temperature and renal disease mortality in Japan from 1979 to 2019: a time-stratified case-crossover analysis

Ambient Temperature and Nervous System Diseases-related Mortality in Japan from 2010 to 2019: A Time-Stratified Case-Crossover Analysis

Ambient Temperature and Nervous System Diseases-related Mortality in Japan from 2010 to 2019: A Time-Stratified Case-Crossover Analysis

Access to mechanical thrombectomy and ischemic stroke mortality in Japan: a spatial ecological study.

Advances in stroke treatment have greatly improved outcomes; however, disparities in access to treatment might increase. Achieving equitable access to stroke treatment is a health policy challenge, as rapid treatment is essential for positive outcomes. This ecological cross-sectional study aimed to determine the relationship between the disparities in spatial accessibility to mechanical thrombectomy (SAMT) and stroke mortality rates in Japan, hypothesizing that disparities in SAMT may increase the differences in stroke mortality between regions. We used the average number of ischemic stroke (IS) deaths between 2020 and 2021 as the response variable; and SAMT, medical resources, and socioeconomic characteristics of each municipality as explanatory variables. A conditional autoregressive model was used to examine the association between the risk of stroke mortality and SAMT. The standardized mortality ratio (SMR) was mapped to understand the nationwide disparities in stroke mortality risk. The median number of IS deaths was 17.5 persons per year in the municipalities (2020 to 2021). The study also found that municipalities with low SAMT were located in the northern part of Japan. The non-spatial regression model results indicated that poor accessibility, a small proportion of bachelor's degrees or higher, and a high proportion of workers in secondary industries were related to high IS mortality. Three models were evaluated using spatial analysis; Model 1 with accessibility indicators alone, Model 2 with medical resources added to Model 1, and Model 3 with socioeconomic characteristics added to Model 2. In Models 1 and 2, the population-weighted spatial accessibility index (PWSAI) showed a significant negative relationship with stroke mortality. However, this was not evident in Model 3. Mapping using Model 3 showed that the high-risk areas were predominantly located in northern Japan, excluding Hokkaido. Access to mechanical thrombectomy was estimated, and regional differences were observed. The relationship between accessibility and IS mortality is unknown; however, regardless of accessibility, municipalities with a high proportion of workers in secondary industries and a small proportion with bachelor's degrees or above are at risk of death from stroke.

Trends in non-Hodgkin lymphoma mortality rate in Japan and the United States: A population-based study.

Characterizing trends in mortality rates with consideration of trends in incidence rates at the population level could help identify unmet needs in public health and provide essential indicators of cancer control. In the late 20th century, the arrival of the first molecular targeted agent, rituximab, for non-Hodgkin lymphoma (NHL) led to a paradigm shift in NHL treatment. However, the public health impact of this arrival has not been fully clarified. Here, we evaluated trends in the mortality and incidence rates of NHL in Japan and the United States. Age-standardized rates of mortality reversed after the introduction of rituximab, around 2000, beginning to decline significantly with annual percent changes (95% confidence interval) of -2.6% (-3.6% to -1.6%) in Japan and - 3.9% (-4.2% to -3.5%) in the United States. Despite an increase in incidence, the mortality in all age groups weakened the upward trends or decreased in both countries. From a long-term perspective, the trends in mortality rates differed between the countries. In the United States, the mortality rate has declined continuously since the introduction of rituximab, with a declining incidence rate. In contrast, in Japan, the mortality rate stopped declining and the incidence rate increased remarkably. The introduction of rituximab has had a substantial impact at the population level across a wide range of individuals. To reduce the disease burden in terms of mortality, elucidating risk factors that lead to a decreasing incidence rate is warranted for NHL, as well as further development of novel treatments.

Excess mortality among adults with mental disorders treated in psychiatric and general medical settings: A population-based cohort study using municipal medical claims data in Japan

ObjectivesTo estimate the excess mortality associated with serious mental illnesses (schizophrenia and bipolar disorder) and common mental disorders (depression and anxiety) at the population level. MethodsWe conducted a population-based, retrospective cohort study in Tsukuba, Japan. Individuals aged 20–74 years and insured for at least 12 months by the National Health Insurance or Late Elders’ Health Insurance as of April 2015 were included (n = 41,618, 29% of the city’s population aged 20–74 years). Individuals with mental disorders (International Classification of Diseases-10 code: F00-F99) were identified in psychiatric and general medical services using medical claims during the 12-month baseline period and classified into mutually exclusive diagnostic subgroups. Their age/sex-adjusted all-cause mortality rate ratios (aMRRs) were estimated and compared to those of individuals without mental disorders. ResultsAltogether, 12.0% of participants had mental disorders (general medical service: 7.2% vs. psychiatric service: 4.8%). Common mental disorders were the most prevalent (8.1%). During the median 48 months of observation, 225 deaths were observed in people with mental disorders. The aMRR was 1.98 (95%CI: 1.70–2.29) for all mental disorders, with a higher rate ratio in psychiatric service than in general medical service users (aMRR: 2.64 [2.12–3.29] vs. 1.70 [1.42–2.04]), 3.57 (2.71–4.70) for serious mental illness, with a higher rate ratio in psychiatric inpatient service than in outpatient service users (aMRR: 5.74 [3.76–8.78] vs. 2.84 [2.00–4.04]), and 1.53 (1.27–1.84) for common mental disorders. ConclusionSerious and common mental disorders in psychiatric and general health services are associated with increased mortality in Japan.

Overcoming the limitations of screening mammography in Japan and Korea: a paradigm shift to personalized breast cancer screening based on ultrasonography.

Screening mammography programs have been implemented in numerous Western countries with the aim of reducing breast cancer mortality. However, despite over 20 years of population-based screening mammography, the mortality rates in Japan and Korea continue to rise. This may be due to the fact that screening mammography is not as effective for Japanese and Korean women, who often have dense breasts. This density decreases the sensitivity of mammography due to a masking effect. Therefore, the early detection of small invasive cancers requires more than just mammography, particularly for women in their 40s. This review discusses the limitations and challenges of screening mammography, as well as the keys to successful population-based breast cancer screening in Japan and Korea. This includes a focus on breast ultrasonography techniques, which are based on histopathologic anatomical knowledge, and personalized screening strategies that are based on risk assessments measured by glandular tissue components.

Effect of renal tubular damage on non-cancer mortality in the general Japanese population living in cadmium non-polluted areas.

This study aimed to clarify the cause-effect relationship between renal tubular damage and non-cancer mortality in the general Japanese population. We conducted a 19-year cohort study including 1110 men and 1,03 women who lived in three cadmium-non-polluted areas in 1993 or 1994. Mortality risk ratios based on urinary β2-microglobulin (β2MG) and N-acetyl-β-glucosaminidase (NAG) concentrations were estimated for specific non-cancer diseases using the Fine and Gray competing risks regression model. In men, continuous urinary NAG (+1 μg/g cre) concentrations were significantly correlated with increased mortality caused by diseases of the respiratory system (hazard ratio (HR): 1.09, 95% confidence interval (CI): 1.03-1.15). Urinary β2MG (+100 μg/g cre) concentrations were significantly correlated with increased mortalities caused by kidney and urinary tract diseases (HR: 1.01, 95% CI: 1.00-1.03), renal diseases (HR: 1.01, 95% CI: 1.00-1.03), renal failure (HR: 1.02, 95% CI: 1.00-1.03), and external causes of mortality (HR: 1.01, 95% CI: 1.00-1.02). In women, urinary NAG (+1 μg/g cre) concentrations were significantly associated with increased mortality caused by ischemic heart diseases (HR: 1.02, 95% CI: 1.00-1.04) and kidney and urinary tract diseases (HR: 1.01, 95% CI: 1.00-1.04). Urinary β2MG (+100 μg/g cre) concentrations were significantly correlated with increased mortality caused by cardiovascular diseases (HR: 1.01, 95%CI: 1.00-1.02), ischemic heart diseases (HR: 1.01, 95%CI: 1.00-1.02), and kidney and urinary tract diseases (HR: 1.02, 95% CI: 1.01-1.03). The present study indicates that renal tubular damage was significantly related to several non-cancer disease causes of mortality in Japan's general population living in cadmium-non-polluted areas.

Impact of the COVID-19 pandemic on the primary lung cancer screening program in Akita Prefecture, a region with the fastest aging population in Japan.

Akita Prefecture has the largest proportion of older inhabitants and the highest cancer mortality rate in Japan. Lung cancer is one of the biggest killers, and early detection is critical. Chest X-ray examinations are the main screening method for lung cancer; however, the COVID-19 pandemic has affected the screening system. Here, we evaluate how COVID-19 has affected lung cancer screening in Akita Prefecture. Using the Akita General Health Corporation database, the average annual number of chest X-ray screening tests, close examinations and lung cancer diagnoses (stratified by sex and age) was evaluated during 2016-2019, and compared with the 2020 values. Furthermore, data on lung cancer registrations from 2018 to 2020 were obtained from the Collaborative Akita Prefecture Hospital-Based Cancer Registration System and analyzed. The average annual number of screening tests, close examinations and lung cancer diagnoses declined (by >50%) between 2016 to 2019 and 2020, especially among older people (aged ≥65 years). Furthermore, by stage, the number of patients with early-stage lung cancer (stage 0-I) decreased, and the number with advanced-stage cancer (stage IV) increased. The COVID-19 pandemic reduced lung cancer screening participation, especially among the older adult population in Akita Prefecture, resulting in a decrease in lung cancer diagnoses through screening. This might have reduced the number of early-stage cancer registrations. It is necessary to improve health education among the public regarding the importance of chest X-ray screening. Geriatr Gerontol Int 2023; 23: 622-627.

Fluctuation of suicide mortality and temporal causality from unemployment duration to suicide mortality in Japan during 2009–2022

Fluctuation of suicide mortality and temporal causality from unemployment duration to suicide mortality in Japan during 2009–2022

Estimation of socioeconomic inequalities in mortality in Japan using national census-linked longitudinal mortality data.

We aimed to develop census-linked longitudinal mortality data for Japan and assess its validity as a new resource for estimating socioeconomic inequalities in health. Using deterministic linkage, we identified, from national censuses for 2000 and 2010 and national death records, persons and deceased persons who had unique personal identifiers (generated using sex, birth year/month, address, and marital status). For the period 2010-2015, 1 537 337 Japanese men and women aged 30-79 years (1.9% in national census) were extracted to represent the sample population. This population was weighted to adjust for confounding factors. We estimated age-standardized mortality rates (ASMRs) by education level and occupational class. The slope index of inequality (SII) and relative index inequality (RII) by educational level were calculated as inequality measures. The reweighted sample population's mortality rates were somewhat higher than those of the complete registry, especially in younger age-groups and for external causes. All-cause ASMRs (per 100 000 person-years) for individuals aged 40-79 years with high, middle, and low education levels were 1078 (95% confidence interval: 1051-1105), 1299 (1279-1320), and 1670 (1634-1707) for men, and 561 (536-587), 601 (589-613), and 777 (745-808) for women, respectively, during 2010-2015. SII and RII by educational level increased among both sexes between 2000-2005 and 2010-2015, which indicates mortality inequalities increased. The developed census-linked longitudinal mortality data provide new estimates of socioeconomic inequalities in Japan that can be triangulated with estimates obtained with other methods.

Cost-effectiveness of human T-cell leukemia virus type 1 (HTLV-1) antenatal screening for prevention of mother-to-child transmission.

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia-lymphoma (ATL) and HTLV-1-associated myelopathy-tropical spastic paraparesis (HAM/TSP) with a poor prognosis. This study aimed to evaluate the cost-effectiveness and health impact of HTLV-1 antenatal screening. A state-transition model was developed for HTLV-1 antenatal screening and no screening over a lifetime horizon from a healthcare payer perspective. A hypothetical cohort of 30-year-old individuals was targeted. The main outcomes were costs, quality-adjusted life-years (QALYs), life expectancy life-years (LYs), incremental cost-effectiveness ratios (ICERs), HTLV-1 carriers, ATL cases, HAM/TSP cases, ATL-associated deaths, and HAM/TSP-associated deaths. The willingness-to-pay (WTP) threshold was set at US$50,000 per QALY gained. In the base-case analysis, HTLV-1 antenatal screening (US$76.85, 24.94766 QALYs, 24.94813 LYs, ICER; US$40,100 per QALY gained) was cost-effective compared with no screening (US$2.18, 24.94580 QALYs, 24.94807 LYs). Cost-effectiveness was sensitive to the maternal HTLV-1 seropositivity rate, HTLV-1 transmission rate with long-term breastfeeding from HTLV-1 seropositive mothers to children, and the cost of the HTLV-1 antibody test. HTLV-1 antenatal screening was cost-effective when the maternal HTLV-1 seropositivity rate was greater than 0.0022 and the cost of the HTLV-1 antibody test was lower than US$94.8. Probabilistic sensitivity analysis using a second-order Monte-Carlo simulation showed that HTLV-1 antenatal screening was 81.1% cost-effective at a WTP threshold of US$50,000 per QALY gained. For 10,517,942 individuals born between 2011 and 2021, HTLV-1 antenatal screening costs US$785 million, increases19,586 QALYs and 631 LYs, and prevents 125,421 HTLV-1 carriers, 4,405 ATL cases, 3,035 ATL-associated deaths, 67 HAM/TSP cases, and 60 HAM/TSP-associated deaths, compared with no screening over a lifetime. HTLV-1 antenatal screening is cost-effective and has the potential to reduce ATL and HAM/TSP morbidity and mortality in Japan. The findings strongly support the recommendation for HTLV-1 antenatal screening as a national infection control policy in HTLV-1 high-prevalence countries.

Ambient temperature and nervous system diseases-related mortality in Japan from 2010 to 2019: A time-stratified case-crossover analysis

BackgroundDespite the substantial disease burden caused by nervous system diseases, few studies have examined the association between ambient temperature and nervous system diseases, especially during cold seasons. Evidence for specific disease subgroups such as Alzheimer's and Parkinson's is also lacking. ObjectivesThis study examined the association between short-term changes in ambient temperature and nervous system diseases-related mortality in ten Japanese prefectures from 1 January 2010 to 31 December 2019. MethodsA two-stage analysis based on a time-stratified case-crossover study design was conducted. A conditional quasi-Poisson regression model with a distributed lag non-linear model for temperature was applied followed by a multivariate random-effects meta-analysis to obtain average associations. Mortality due to all and cause-specific nervous system diseases (major neurodegenerative diseases, Alzheimer's, and Parkinson's) were analyzed, with consideration for sex and age (0–84 and 85+ years old) subgroups. ResultsWe analyzed 162,315 death cases due to nervous system diseases. Cold was associated with all categories of nervous system diseases-related mortality, but not heat. The estimated relative risks for cold, obtained by comparing the 2.5th percentile of daily mean temperature distribution to the minimum mortality temperature (MMT), were 1.43 (95 % CI: 1.28–1.60), 1.37 (95 % CI: 1.17–1.59), 1.53 (95 % CI: 1.07–2.01), and 1.54 (95 % CI: 1.13–2.10) for all nervous system diseases, major neurodegenerative diseases, Alzheimer's, and Parkinson's, respectively. These associations were also observed in the sex and age subgroups in general but without evidence of effect modification. Heat (the 97.5th percentile of daily mean temperature distribution vs. MMT) was associated with Parkinson’s disease-related mortality among those aged 85 years and over. DiscussionCold was associated with an increased risk of nervous system disease-related mortality. The effect of heat was not observed, except for mortality among the elderly aged 85 years and older with Parkinson's disease.

Longitudinal trajectories of region-level suicide mortality in Tokyo, Japan, 2011 to 2021

Background: Suicide mortality in Japan has declined over a period of more than 10 years, however, differences in longitudinal trajectories at a regional level are not well characterized. Objective was to clarify the longitudinal suicide mortality trajectories at the regional level in Tokyo from 2011 to 2021 by considering spatial smoothing, before and during the COVID-19 pandemic. Methods: This longitudinal cross-sectional analysis used fifty-four regions in Tokyo, Japan. Suicide mortality trends used data from the Cabinet Office of the Japanese government from 2011 to 2021. Regional social and environmental characteristics were used as 10 covariates. Empirical Bayes estimates for the standardized mortality ratio were obtained. A conditional autoregressive (CAR) model was applied to capture the spatial correlation for a crude and adjusted with 10 covariates using OpenBUGS. Spatial clusters were also identified by FlexScan, SaTScan, and Tango’s test. Results: Longitudinal trajectories for both males and females were similar to a decreasing trend in all Japan until 2019. In 2020, the beginning of the COVID-19 pandemic, the age-specific suicide deaths were the highest among those in their 20s. However, those were the highest among males in their 50s in 2021. The results of the CAR models adjusted for 10 covariates detected several regions as having higher suicide rates, but those regions were somewhat varied. Conclusion: During the COVID-19 pandemic, both sexes in their 20s and males in their 50s showed a tendency toward an increase in suicides. The detected regions by spatial epidemiology varied with sex.

Limits of Subsidized Medical Care in Reducing the Effect of Socioeconomic Disparities: Liver Cirrhosis Mortality in Japan

Limits of Subsidized Medical Care in Reducing the Effect of Socioeconomic Disparities: Liver Cirrhosis Mortality in Japan

Regional Variations in Coronavirus Disease 2019 Mortality in Japan: An Ecological Study.

As the characteristics of coronavirus disease 2019 (COVID-19) vary across regions and countries, the relationship between regional characteristics, such as the distribution of physicians and hospital beds, and COVID-19 mortality was assessed in the 47 prefectures of Japan. This ecological study was based on the number of patients with COVID-19 by prefecture during the seventh wave of COVID-19 in Japan (June-October 2022). COVID-19 mortality was indexed as the number of COVID-19 deaths divided by the number of new COVID-19 cases. Data on regional factors, such as population size, number of physicians, and hospital beds by prefecture, were obtained from government statistics. Correlations between regional characteristics and COVID-19 mortality index were analyzed by dividing the 47 prefectures into two groups at the median level of population size (more populated group [MPG] ≥ 1.6 million and less populated group [LPG] < 1.6 million). The COVID-19 mortality index (mean 12.7, minimum-maximum: 4.7-25.7) was correlated negatively with the number of physicians per hospital bed (r = -0.386, p = 0.007) and positively with the number of long-term care facilities per 10,000 population (r = 0.397, p = 0.006) and aging rate (the proportion of population aged ≥ 65 years) (r = 0.471, p = 0.001). The two groups varied with respect to the number of physicians (28.7 physicians in the LPG vs. 26.1 physicians in the MPG, p = 0.038) and hospital beds (156 beds in the LPG vs. 119 beds in the MPG, p < 0.001) per 10,000 population. In the multiple regression analysis, the COVID-19 mortality index was correlated negatively with the number of physicians per hospital bed (β = -0.543, p = 0.024) and positively with the aging rate (β = 0.434, p = 0.032) in the LPG, with nonsignificant correlations in the MPG. The data may suggest a need of improvement in the distribution of physicians and hospital beds in the healthcare system in regions with smaller and older populations to reduce the rate of COVID-19.

The Current Status of Suicide and Medical Care System in Japan: An Analysis of 81,407 Patients Using the Diagnosis Procedure Combination Database.

Japan has a high suicide mortality rate compared to other developed countries. To reduce suicide mortality in Japan, it is important to systematically analyze factors related to death of patients with suicide attempt. This study aimed to analyze the characteristics of patients with suicide attempt, and the factors related to their death using the Diagnosis Procedure Combination (DPC) data- a nationally representative inpatient database. We collected 81,407 cases of suicide attempt from 2016 to 2018 from DPC data and performed a multilevel logistic analysis of factors associated with death discharges. The analysis results showed that patients who received psychiatric liaison care had a lower mortality rate, but only 0.6% of surviving patients received psychiatric liaison care after admission. The odds ratio (OR) of death was high for hanging (28.86; p < 0.001) and jumping (16.28; p < 0.001), compared to wrist cutting. Patients without a psychiatric diagnosis were more likely to choose means such as hanging (14.1%) than those with a psychiatric disorder. The weekend cases had a higher OR of death than weekday (Wednesday as reference) cases (Friday 1.14, p = 0.011; Saturday 1.60, p < 0.001; Sunday 1.67, p < 0.001). Based on these findings, we suggest that improving the availability and quality of psychiatric care in acute care hospitals and primary care settings, as well as enhancing the emergency department system on weekends, could help reduce the mortality of suicide attempts.

Frailty and all-cause and cause-specific mortality in Japan

BackgroundIn aging societies, there is an increasing focus on the concept of frailty. However, there is no consistent means to assess this concept. We assessed frailty using the Kihon Checklist (KCL), which is widely used in Japan, and examined the association between frailty and all-cause and cause-specific mortality in Japan, the most aged society in the world. MethodsThis was a retrospective cohort study, and we analyzed 43,312 participants aged ≥ 65 years who were enrolled in basic health checkups in Okayama City, Japan. We defined the frailty status of the participants using the KCL. To assess the association of frailty status with all-cause and cause-specific mortality, we used cause-specific Cox proportional hazard models to estimate hazard ratios (HRs), adjusting for individual potential confounders. Mean follow-up time was 9.3 years. ResultsThe fully adjusted HR for all-cause mortality was 1.34 (95% confidence interval [CI]: 1.27-1.41) for the prefrail group and 2.22 (95% CI: 2.11-2.33) for the frail group. A similar pattern was observed for cardiovascular disease, respiratory disease, and cancer mortality. Younger people (65–74 years) and women tended to have higher effect estimates than older people (≥ 75 years) and men. ConclusionPrefrailty and frailty can increase the risk of both all-cause and cause-specific mortality. Our study suggests that to support frail patients, it could be effective to focus on the prevention and management of cardiovascular and respiratory disease, and that the KCL may be useful as a method of screening for frailty.

Long-Term Projections of Cancer Incidence and Mortality in Japan and Decomposition Analysis of Changes in Cancer Burden, 2020-2054: An Empirical Validation Approach.

The aim of this study was to project new cancer cases/deaths forward to 2054, and decompose changes in cancer cases/deaths to assess the impact of demographic transitions on cancer burden. We collected data on cancer cases/deaths up to 2019, empirically validated the projection performance of multiple statistical models, and selected optimal models by applying time series cross-validation. We showed an increasing number of new cancer cases but decreasing number of cancer deaths in both genders, with a large burden attributed to population aging. We observed the increasing incidence rates in most cancer sites but reducing rates in some infection-associated cancers, including stomach and liver cancers. Colorectal and lung cancers were projected to remain as leading cancer burdens of both incidence and mortality in Japan over 2020-2054, while prostate and female breast cancers would be the leading incidence burdens among men and women, respectively. Findings from decomposition analysis require more supportive interventions for reducing mortality and improving the quality of life of Japanese elders. We emphasize the important role of governments and policymakers in reforming policies for controlling cancer risk factors, including oncogenic infections. The rapid increase and continued presence of those cancer burdens associated with modifiable risk factors warrant greater efforts in cancer control programs, specifically in enhancing cancer screening and controlling cancer risk factors in Japan.

Effects of Low-Dose Colchicine on Serum High-Sensitivity C-Reactive Protein Level in Coronary Artery Disease Patients with Type 2 Diabetes Mellitus and Enhanced Inflammatory Response Protocol for a Randomized, Double-Blind, Placebo-Controlled, Phase 2, Dose-Finding Study

Although cardiovascular mortality in Japan is lower than in other industrialized countries, clinical outcomes in coronary artery disease (CAD) patients with type 2 diabetes mellitus (T2DM) remain poor despite multiple evidence-based drug therapies and interventions. We assumed that part of residual risk in these patients may be attributable to enhanced inflammation, which can be inhibited presumably by colchicine. However, dose-responsiveness of anti-inflammatory effect of colchicine has not been elucidated. Therefore, we designed a multicenter, randomized, double-blinded, parallel-group study to explore the dose-dependent effects of low-dose colchicine on serum high-sensitivity C-reactive protein (hs-CRP) concentration and safety in CAD patients with T2DM and enhanced inflammatory response as a phase 2 study. Enhanced inflammatory response was defined as peripheral white-blood cell count ≥7,000/μL. Patients (N = 63) will be randomly assigned to two doses of colchicine 0.25 mg/day, 0.5 mg/day, or placebo in a 1:1:1 ratio once daily for 12 weeks. Changes in serum hs-CRP levels will be evaluated as the primary endpoint, and changes in flow-mediated vasodilation and plasma myeloperoxidase levels will be evaluated as secondary endpoints. The results of this study will contribute to the development of a protocol for a planned future phase 3 trial to estimate the reduction in CAD. The present study describes the rationale, design, and methods of the trial.

Daytime napping and risk of liver cancer: A large population-based prospective cohort study

Introduction and ObjectivesLiver cancer is a major cause of morbidity and mortality in Japan and worldwide. Daytime napping is a common behavior, especially among older adults, that was related in previous research to unfavorable health conditions. Herein, we investigated the association between daytime napping and liver cancer risk. Materials and MethodsIn this prospective cohort study, data from 51,185 participants aged 40–79 years and registered in the Japan Collaborative Cohort Study (JACC Study) were analyzed. Incident cases of liver cancer were diagnosed using cancer registries, hospital records, and death certificates. Daytime napping was assessed using the JACC baseline self-administered questionnaire. We used the Cox regression to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of incident liver cancer among participants in the age categories of the 40s, 50s, 60s, and 70s who reported daytime napping compared with their counterparts who did not. ResultsWithin 669,734 person-years of follow-up, 341 participants developed liver cancer. Daytime napping was associated with a higher risk of liver cancer among participants who were in their 60s and 70s of age after adjusting for sex: HRs (95% CIs) 1.88 (1.35–2.61) and 1.96 (1.18–3.26), lifestyle and medical history: 1.76 (1.27–2.47) and 1.82 (1.07–3.09), and history of liver diseases: 1.66 (1.18–2.34) and 1.72 (1.01–2.94), respectively. No associations were detected among participants from the 40s and 50s age groups. ConclusionsDaytime napping was associated with a higher risk of liver cancer among older adults.