Emerging evidence indicates that sleep duration is associated with health outcomes. However, the relationship of sleep duration with long-term health is unclear. This study was designed to determine the relationship of sleep duration with mortality as a parameter for long-term health in a large prospective cohort study in Korea.
The study population included 13 164 participants aged over 20 years from the Korean Multi-center Cancer Cohort study. Information on sleep duration was obtained through a structured questionnaire interview. The hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality were estimated using a Cox regression model. The non-linear relationship between sleep duration and mortality was examined non-parametrically using restricted cubic splines.
The HRs for all-cause mortality showed a U-shape, with the lowest point at sleep duration of 7 to 8 hours. There was an increased risk of death among persons with sleep duration of ≤5 hours (HR, 1.21; 95% CI, 1.03 to 1.41) and of ≥10 hours (HR, 1.36; 95% CI, 1.07 to 1.72). In stratified analysis, this relationship of HR was seen in women and in participants aged ≥60 years. Risk of cardiovascular disease-specific mortality was associated with a sleep duration of ≤5 hours (HR, 1.40; 95% CI, 1.02 to 1.93). Risk of death from respiratory disease was associated with sleep duration at both extremes (≤5 and ≥10 hours).
Sleep durations of 7 to 8 hours may be recommended to the public for a general healthy lifestyle in Korea.
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Diabetes and obesity each increases mortality, but recent papers have shown that lean Asian persons were at greater risk for mortality than were obese persons. The objective of this study is to determine whether an interaction exists between body mass index (BMI) and diabetes, which can modify the risk of death by cardiovascular disease (CVD).
Subjects who were over 20 years of age, and who had information regarding BMI, past history of diabetes, and fasting blood glucose levels (n=16 048), were selected from the Korea Multi-center Cancer Cohort study participants. By 2008, a total of 1290 participants had died; 251 and 155 had died of CVD and stroke, respectively. The hazard for deaths was calculated with hazard ratio (HR) and 95% confidence interval (95% CI) by Cox proportional hazard model.
Compared with the normal population, patients with diabetes were at higher risk for CVD and stroke deaths (HR, 1.84; 95% CI, 1.33 to 2.56; HR, 1.82; 95% CI, 1.20 to 2.76; respectively). Relative to subjects with no diabetes and normal BMI (21 to 22.9 kg/m2), lean subjects with diabetes (BMI <21 kg/m2) had a greater risk for CVD and stroke deaths (HR, 2.83; 95% CI, 1.57 to 5.09; HR, 3.27; 95% CI, 1.58 to 6.76; respectively), while obese subjects with diabetes (BMI ≥25 kg/m2) had no increased death risk (
This study suggests that diabetes in lean people is more critical to CVD deaths than it is in obese people.
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To examine the association between alcohol consumption habit, types of beverages, alcohol consumption quantity, and overall and cancer-specific mortality among Korean adults.
The alcohol consumption information of a total of 16 320 participants who were 20 years or older from the Korean Multi-center Cancer Cohort were analyzed to examine the association between alcohol consumption habit and mortality (median follow-up of 9.3 years). The Cox proportional hazard model was used to estimate the hazard ratio (HR) of alcohol consumption to mortality adjusting for age, sex, geographic areas, education, smoking status, and body mass index.
Alcohol drinkers showed an increased risk for total mortality compared with never drinkers (HR, 1.72; 95% confidence interval [CI], 1.38 to 2.14 for past drinkers; HR, 1.21; 95% CI, 1.06 to 1.39 for current drinkers), while past drinkers only were associated with higher risk for cancer deaths (HR, 1.84; 95% CI, 1.34 to 2.53). The quantity of alcohol consumed per week showed a J-shaped association with risk of mortality. Relative to light drinkers (0.01 to 90 g/wk), never drinkers and heavy drinkers (>504 g/wk) had an increased risk for all-cause and cancer deaths: (HR, 1.18; 95% CI, 0.96 to 1.45) and (HR, 1.39; 95% CI, 1.05 to 1.83) for all-cause mortality; and (HR, 1.55; 95% CI, 1.15 to 2.11) and (HR, 2.07; 95% CI, 1.39 to 3.09) for all cancer mortality, respectively. Heavy drinkers (>504 g/wk) showed an elevated risk for death from stomach and liver cancers.
The present study supports the existence of a J-shaped association between alcohol consumption quantity and the risk of all-cause and cancer deaths. Heavy drinkers had an increased risk of death from cancer overall and liver and stomach cancer.
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