Passive Smoking at Home by Socioeconomic Factors in a Japanese Population: NIPPON DATA2010

BACKGROUND

Long-term passive exposure to cigarette smoke has been reported to affect the health of non-smokers. This study aims to investigate the relationships among socioeconomic factors and passive smoking at home in the non-current smokers of a representative sample from a general Japanese population.

METHODS

Data are from NIPPON DATA2010. Among 2,891 participants, 2,288 non-current smokers (1,763 never smokers and 525 past smokers) were analyzed in the present study. Cross-sectional analyses were performed on the relationships among socioeconomic factors and passive smoking at home (several times a week or more) in men and women separately. Socioeconomic factors were employment, length of education, marital status, and equivalent household expenditure. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a multivariable logistic regression model.

RESULTS

The multivariable-adjusted model showed that employed women had a higher risk of passive smoking than unemployed women (OR 1.44; 95% CI, 1.06-1.96). Women with 9 years or less of education had a higher risk of passive smoking at home than women with 13 years and more of education (OR 2.37; 95% CI, 1.49-3.78). Single women had a lower risk of passive smoking at home (OR 0.53; 95% CI, 0.37-0.77) than married women. No significant associations were observed in men.

CONCLUSIONS

An employed status, lower education, and being single were associated with passive smoking at home in the non-current smoking women of a representative Japanese population.

Differences in Lifestyle Improvements With the Intention to Prevent Cardiovascular Diseases by Socioeconomic Status in a Representative Japanese Population: NIPPON DATA2010

BACKGROUND

The relationships among socioeconomic status and lifestyle improvements have not yet been examined in a representative Japanese population.

METHODS

We analyzed data from 2,647 participants (1,087 men and 1,560 women) who participated in NIPPON DATA2010. This survey inquired about lifestyle improvements and socioeconomic status. Education was categorized as low (≤9 years), middle (10-12 years), and high (≥13 years). Marital status was categorized as married, divorced, widowed, and never married/other. A multivariable logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of lifestyle improvements with the intention of preventing cardiovascular diseases for educational attainment and marital status, with adjustments for age and awareness of cardiovascular disease risk factors.

RESULTS

Overall, 1,507 (56.9%) participants practiced prevention and improvements in hypertension, diabetes, elevated cholesterol, and metabolic syndrome, and the OR of lifestyle improvements was significantly higher with a high education than with a low education in men (OR 2.86; 95% CI, 1.96-4.17) and women (OR 2.36; 95% CI, 1.67-3.33). The number of participants who practiced prevention and improvements in hypertension, diabetes, elevated cholesterol, and metabolic syndrome was significantly lower in divorced than in married men (OR 0.46; 95% CI, 0.22-0.95) and women (OR 0.53; 95% CI, 0.33-0.86).

CONCLUSIONS

Specific differences caused by educational attainment and marital status may exist in lifestyle improvements.

Relationships among Socioeconomic Factors and Self-rated Health in Japanese Adults: NIPPON DATA2010

BACKGROUND

The distributions of socioeconomic status (SES) factors have been changing in Japan. We examined the relationships among SES and self-rated health (SRH) in Japanese adults.

METHODS

We analyzed 1,178 men and 1,555 women. We showed the distribution of SRH by sex and age and examined cross-sectional relationships among educational attainment, marital/living statuses, working status, household income and expenditure, and fine SRH (defined as excellent, very good, or good). We adjusted for age, subjective symptoms, visiting doctors, monthly equivalent household expenditure (EHE), and living in their own house.

RESULTS

The age-standardized prevalence of fine SRH was 79% and 73% among men and women, respectively. Among men, graduating from high school (adjusted odds ratio [aOR] 1.53; 95% confidence interval [CI], 1.07-2.19, relative to graduating from elementary or junior high school) and university or junior college (aOR 1.74; 95% CI, 1.15-2.62) was associated with fine SRH. Among women, graduating from university or junior college was associated with fine SRH (aOR 1.65; 95% CI, 1.12-2.46). Neither marital/living status nor working status was associated with SRH after adjustments for age in either sex. Among women, high EHE and income were associated with fine SRH (the highest expenditure group: aOR 1.80; 95% CI, 1.22-2.65; the highest income group: aOR 2.15; 95% CI, 1.34-3.46, relative to the corresponding lowest group). These simple relationships were not observed for men.

CONCLUSIONS

High educational attainment was associated with fine SRH. Relationships among household income, EHE, and fine SRH differed by sex.

Relationship Between Socioeconomic Status and the Prevalence of Underweight, Overweight or Obesity in a General Japanese Population: NIPPON DATA2010

BACKGROUND

Socioeconomic status (SES) imbalances in developed and developing countries may result in individuals being overweight and obese. However, few studies have investigated this issue in Japan. We herein examined the relationship between SES and being underweight, overweight or obese according to sex and age groups (20-64 or ≥65 years) in Japan.

METHODS

In 2010, we established a cohort of participants in the National Health and Nutrition Survey of Japan. We divided 2,491 participants (1,081 men and 1,410 women) according to the WHO definitions of underweight, overweight or obesity and performed multinomial logistic analyses using BMI <18.5 kg/m2 (underweight), BMI 25.0-29.9 kg/m2 (overweight), and BMI ≥30.0 kg/m2 (obese) versus BMI 18.5-24.9 kg/m2 (normal) as the outcome, with SES groups as the main explanatory variables.

RESULTS

In adult men, a lower education level relative to a higher education level was inversely associated with obesity after adjustments for other SESs (odds ratio [OR] 0.41; 95% confidence interval [CI], 0.18-0.96). However, in adult women, lower education level was positively associated with being overweight and obese (OR 1.67; 95% CI, 1.07-2.49 for overweight and OR 2.66; 95% CI, 1.01-7.01 for obese). In adult women, a lower household income was positively associated with being overweight and obese (obese: OR 4.84; 95% CI, 1.36-17.18 for those with a household income <2 million JPY relative to those with ≥6 million JPY).

CONCLUSIONS

In adult women, a lower education level and lower household income were positively associated with being overweight or obese. In contrast, in adult men, a lower education level was inversely associated with obesity. Gender and age differences in SESs affect the prevalence of being overweight or obese.

Socioeconomic Status and Knowledge of Cardiovascular Risk Factors: NIPPON DATA2010

BACKGROUND

The relationship between socioeconomic status (SES) and knowledge of cardiovascular risk factors remains unknown in a general Japanese population.

METHODS

Of 8,815 participants from 300 randomly selected areas throughout Japan, 2,467 participants who were free of cardiovascular disease and who provided information on SES in the National Health and Nutrition Survey of Japan 2010 were enrolled in this cross-sectional analysis. SES was classified according to the employment status, length of education, marital and living statuses, and equivalent household expenditure (EHE). Outcomes were ignorance of each cardiovascular risk factor (hypertension, diabetes, hypercholesterolemia, low high-density lipoprotein [HDL] cholesterol, arrhythmia, and smoking) and insufficient knowledge (number of correct answers <4 out of 6).

RESULTS

A short education and low EHE were significantly associated with a greater ignorance of most cardiovascular risk factors. A short education (<10 years) was also associated with insufficient knowledge of overall cardiovascular risk factors: age- and sex-adjusted odds ratios (OR) were 1.92 (95% confidence interval [CI], 1.51-2.45) relative to participants with ≥13 years of education. Low EHE was also associated with insufficient knowledge (age- and sex-adjusted OR 1.24; 95% CI, 1.01-1.51 for the lowest quintile vs the upper 4 quintiles). These relationships remained significant, even after further adjustments for regular exercise, smoking, weekly alcohol consumption, body mass index, hypertension, diabetes mellitus, hypercholesterolemia, and low HDL cholesterol.

CONCLUSION

Participants with a short education and low EHE were more likely to have less knowledge of cardiovascular risk factors.

Socioeconomic Status Associated With Urinary Sodium and Potassium Excretion in Japan: NIPPON DATA2010

BACKGROUND

Although socioeconomic status (SES) may affect food and nutrient intakes, few studies have reported on sodium (Na) and potassium (K) intakes among individuals with various SESs in Japan. We investigated associations of SES with Na and K intake levels using urinary specimens in a representative Japanese population.

METHODS

This was a cross-sectional study of 2,560 men and women (the NIPPON DATA2010 cohort) who participated in the National Health and Nutrition Survey Japan in 2010. Casual urine was used to calculate estimated excretion in 24-hour urinary Na (E24hr-Na) and K (E24hr-K). The urinary sodium-to-potassium (Na/K) ratio was calculated from casual urinary electrolyte values. An analysis of covariance was performed to investigate associations of aspects of SES, including equivalent household expenditure (EHE), educational attainment, and job category, with E24hr-Na, E24hr-K, and the Na/K ratio for men and women separately. A stratified analysis was performed on educational attainment and the job category for younger (<65 years) and older (≥65 years) participants.

RESULTS

In men and women, average E24hr-Na was 176.2 mmol/day and 172.3, average E24hr-K was 42.5 and 41.3, and the average Na/K ratio was 3.61 and 3.68, respectively. Lower EHE was associated with a higher Na/K ratio in women and lower E24hr-K in men and women. A shorter education was associated with a higher Na/K ratio in women and younger men, and lower E24hr-K in older men and women.

CONCLUSION

Lower EHE and a shorter education were associated with a lower K intake and higher Na/K ratio estimated from casual urine specimens in Japanese men and women.

Factors Related to Participation in Health Examinations for Japanese National Health Insurance: NIPPON DATA2010

BACKGROUND

This study investigated relationships among socioeconomic factors and participation in health examinations for Japanese National Health Insurance (NHI) using a representative Japanese population.

METHODS

We used the linkage database of NIPPON DATA2010 and Comprehensive Survey of Living Conditions 2010. Participants with NHI aged 40-74 years were included in the analysis. Prevalence ratios (PRs) for participation in health examinations in the past year were set as an outcome. Participant characteristics, including sex, age, socioeconomic factors (educational attainment, employment, equivalent household expenditure [EHE], house ownership, and marital status), laboratory measures, and lifestyle were included in an age-stratified modified Poisson regression analysis to examine relationships.

RESULTS

The number of study participants was 812, and 564 (69.5%) participated in health examinations in the past year. Among those aged 40-64 years, there was no significant PR for socioeconomic factors. Among those aged 65-74 years, high (≥13 years) educational attainment (adjusted PR, 1.22; 95% confidence interval [CI], 1.05-1.41) and house ownership (PR 1.40; 95% CI, 1.11-1.77) were positively associated with participation, while high (4th quartile) EHE (PR 0.84; 95% CI, 0.73-0.97) was negatively associated.

CONCLUSION

These results suggest that high educational attainment, house ownership, and low EHE were positive factors for participation in health examinations among those aged 65-74 years.

Socioeconomic Inequalities in Oral Health among Middle-Aged and Elderly Japanese: NIPPON DATA2010

BACKGROUND

Most studies on socioeconomic inequalities in oral health have not considered the effects of behavioral and biological factors and age differences. Furthermore, the nationwide status of inequalities remains unclear in Japan.

METHODS

We analyzed data from 2,089 residents aged ≥40 years throughout Japan. The lowest quartile of the number of remaining teeth for each 10-year age category was defined as poor oral health. Behavioral and biological factors included smoking status, obesity, diabetes mellitus, high-sensitivity C-reactive protein, and the use of dental devices. Multiple logistic regression analyses were conducted to examine the associations of educational attainment and equivalent household expenditure (EHE) with oral health, and stratified analyses by age category were also conducted (40-64 years and ≥65 years).

RESULTS

Lower education and lower EHE were significantly associated with an increased risk of poor oral health after adjusting for age, sex, employment status, marital and living statuses, and EHE/education; the odds ratio for junior high school education compared with ≥college education was 1.84 (95% confidence interval [CI], 1.36-2.49), and the odds ratio of the lowest compared with the highest EHE quartile was 1.91 (95% CI, 1.43-2.56). Further adjustments for behavioral and biological factors attenuated but did not eliminate these associations. EHE was significantly associated with oral health among elderly adults only, with a significant interaction by age category.

CONCLUSIONS

Those with a lower education and those with lower EHE had a significantly higher risk of poor oral health, even after adjustments for behavioral and biological factors.

Relationships among Food Group Intakes, Household Expenditure, and Education Attainment in a General Japanese Population: NIPPON DATA2010

BACKGROUND

A lower socioeconomic status (SES) may be related to the intake of unhealthy food; however, this relationship has not been examined in detail. This study was undertaken to examine relationships among food group intakes and SES in a representative Japanese population.

METHODS

This was a cross-sectional study using the baseline data of NIPPON DATA2010, which is a prospective cohort study of the National Health and Nutrition Survey in Japan. A total of 2,898 participants were included in the baseline survey in 2010. The effects of age (<65 years and ≥65 years), equivalent household expenditure (EHE), and education attainment on food group intakes (gram per 1,000 kcal) were analyzed using a two-way analysis of variance.

RESULTS

When EHE was lower, cereal intake was higher in men and women. Among men, fish, milk, and alcohol intakes were reduced with lower EHE. Among women, vegetable intake was reduced with lower EHE. In men and women, cereal intake was higher with lower education attainment. In contrast, meat intake was reduced with lower education attainment.

CONCLUSIONS

Lower SES was associated with a higher cereal intake and lower vegetable, fish, meat, and milk intakes in a representative Japanese population. Socioeconomic discrepancies need to be considered in order to promote healthier dietary habits.

Macronutrient Intake and Socioeconomic Status: NIPPON DATA2010

BACKGROUND

This study examined the relationships among household income, other SES indicators, and macronutrient intake in a cross-sectional study of a representative Japanese population.

METHODS

In 2010, we established a cohort of participants in the National Health and Nutrition Survey (NHNS) from 300 randomly selected areas throughout Japan. A total of 2,637 participants (1,145 men and 1,492 women) were included in the study. Data from NHNS2010 and the Comprehensive Survey of Living Conditions 2010 (CSCL2010) were merged, and relationships among macronutrient intake and SES were evaluated. Additionally, socioeconomic factors associated with a risk of a higher carbohydrate/lower fat intake beyond dietary recommendations were evaluated.

RESULTS

Household income was positively associated with fat intake (P = 0.001 for men and <0.001 for women) and inversely associated with carbohydrate intake (P = 0.003 for men and <0.001 for women) after adjustments for age and other SES variables. Similar relationships were observed between equivalent household expenditure (EHE) and macronutrient intake; however, these relationships were weaker than those of household income. Older age was the factor most strongly associated with a high carbohydrate/low fat intake, followed by household income, EHE, education levels, and occupation type.

CONCLUSIONS

Older age was the factor most strongly associated with a high carbohydrate/low fat intake, and some aspects of SES, such as household income, EHE, education levels, and occupation type, were independently associated with an imbalanced macronutrient intake. SES may affect the health status of individuals through the intake of macronutrients.

Construction of a simulation model and evaluation of the effect of potential interventions on the incidence of diabetes and initiation of dialysis due to diabetic nephropathy in Japan

Background

The prevalence of diabetes mellitus is a growing public health concern in Japan. We developed a simulation model to predict the number of people with diabetes and those on dialysis due to diabetic nephropathy. In addition, we used the model to simulate the impact of possible interventions on the number of people with diabetes and those on dialysis due to diabetic nephropathy in the near future.

Methods

A simulation model with aging chains for diabetes management was built using system dynamics. The model was calibrated to population data from 2000 to 2015 (sex- and age category-specific population, the prevalence of diabetes, and the number of patients on dialysis due to diabetic nephropathy). We extrapolated the model up to 2035 in order to predict future prevalence of diabetes and related dialysis (base run). We also ran the model, hypothesizing that incidence of diabetes and/or related dialysis would be reduced by half from 2015 to 2025 and that this rate would be maintained until 2035, in order to investigate the effects of hypothetical interventions on future prevalence.

Results

The developed model forecasted the population with diabetes to increase until 2028 (5.58 million males and 3.34 million females), and the population on dialysis due to diabetic nephropathy to increase until 2035 (113,000 males and 48,000 females). Simulation experiments suggested that diabetes prevention interventions would decrease the number of patients on dialysis in 2035 by 13.8% in males and 12.6% in females compared to the base run. In contrast, interventions aiming to avoid dialysis initiation for patients with diabetes would decrease the number of patients on dialysis by 37.8% in males and 38.1% in females.

Conclusions

We successfully developed a simulation model to project the number of patients with diabetes and those on dialysis due to diabetic nephropathy. Simulation experiments using the model suggested that, as far as the perspective of the next 20 years, intervention to prevent dialysis is an important means of bending the increasing curve of dialysis in the population with diabetes. Simulation analysis may be useful when making and evaluating health policies related to diabetes and other chronic diseases.

Electronic supplementary material

The online version of this article (10.1186/s12913-017-2784-0) contains supplementary material, which is available to authorized users.

Characteristics of food group intake by household income in the National Health and Nutrition Survey, Japan

This study examines the relationship between of food group intake and household income in a representative Japanese population. A total of 11,015 subjects (5,127 men and 5,888 women) aged 20 to 79 years, in 5,475 households who were part of the National Health and Nutrition Survey, Japan, in 2010 and 2011 were analyzed. Dietary intake was recorded for one day in November for those aged one year and older, from 300 randomly selected survey districts. Household income per year was recorded in the questionnaire in three categories: low (<2 million yen), middle (2-6 million yen) and high (>=6 million yen). Multilevel regression modelling was applied to take into account the hierarchical data structure of subjects nested within households, and households nested within survey districts. Dichotomous variables divided at the median intake of each food group were used. In a model where sex, age, household size and population size of municipalities to which survey districts belonged were adjusted, the total energy intake was found to be highest in individuals from middle income households, and lowest for those from low income households. In models where a total energy intake was additionally adjusted, household members with low and middle incomes had a significantly higher intake of cereals, and a lower intake of potatoes and starches, pulses, vegetables, fruits, mushrooms, fish and shellfish, milk and seasonings and spices compared with those with high incomes. In conclusion, household members with lower incomes in Japan consumed more staple foods, but less vegetable, fruit and fish.

Prevalence of Inadequate Nutrient Intake in Japanese Community-Dwelling Older Adults Who Live Alone

Dietary assessment of community-dwelling Japanese older adults who live alone using Dietary Reference Intakes (DRIs) is limited. The present study aimed to estimate the prevalence of inadequate nutrient intake among Japanese community-dwelling older adults by sex and young-old and old-old population groups to identify the most vulnerable groups that need support. A cross-sectional survey was conducted from October 2012 to October 2013 with community-dwelling adults aged 65 y or older who lived alone. Participants were drawn from six cities in four Japanese prefectures. We used two days of dietary survey data to estimate participants' usual intake. The proportion of inadequate intake was assessed using the Estimated Average Requirement (EAR) cut-point method, Tolerable Upper Intake Level, and the tentative dietary goal for preventing life-style related diseases (DG) based on DRIs for Japanese, 2015. Data for 494 participants (162 male, 332 female) over 988 d were examined to assess nutrient intake. We calculated the proportion of inadequate intake between males and females and between young-old and old-old population groups (65-74 y and ≥75 y) using chi-square or Fisher's exact tests. For six nutrients, the estimated proportion of participants with a usual intake below EAR was higher in males than females. In addition, a higher estimated proportion of female participants was within the DG range for the percentage of energy from protein, fat, and carbohydrates, and had a usual intake of two nutrients above DG than males. Our findings showed that among Japanese older adults, males were more vulnerable in terms of inadequate nutrient intake compared with females.

Trends in prevalence and management of diabetes and related vascular risks in Japanese adults: Japan National Health and Nutrition Surveys 2003-2012

AIMS

To examine temporal changes in health system performance for the control of diabetes and related risks for vascular complications in Japan over a decade.

METHODS

Data of 51,128 individuals aged ≥20years were obtained from the National Health and Nutrition Surveys in 2003-2012. Diabetes was defined as currently being treated by insulin or oral hypoglycaemic agents or having a glycated haemoglobin (HbA1c) level ≥6.5% (≥48mmol/mol). We estimated the prevalence and proportions of people with diabetes being treated and achieving target goals of HbA1c <7.0% (<53mmol/mol), blood pressure <130/80mmHg, and non-high-density lipoprotein cholesterol <130mg/dL. All estimates were age-standardized using the Japanese population in 2010.

RESULTS

The age-standardized prevalence of diabetes remained constant at approximately 8% and was significantly higher in men (P<0.001) and in individuals age ≥65years (P<0.001) throughout the study period. The proportion of people with diabetes being treated significantly increased from 41.8% (95% confidence interval, 37.2-46.5%) in 2003 to 54.9% (51.9-57.8%) in 2012, and the proportion of those having controlled HbA1c significantly increased from 13.4% (10.3-17.3%) in 2003 to 28.8% (26.3-31.5%) in 2012. These two rates were significantly higher in age ≥65years compared with younger adults in most of the survey years (P<0.05). The control rates of blood pressure and non-high-density lipoprotein cholesterol remained around 20% and 30-40%, respectively.

CONCLUSIONS

Diabetes management in Japan has improved over the past decade but is still inadequate for prevention of vascular complications.

Combined associations of physical activity and dietary intake with health status among survivors of the Great East Japan Earthquake

BACKGROUND AND OBJECTIVES

Each of the effects of physical activity and dietary intake on health is well known, but combined associations of physical activity and dietary intake on health has not been reported yet. Physical activity and dietary intake are key factors for maintaining health of survivors of the Great East Japan Earthquake in 2011. This study aimed to examine combined associations of physical activity and dietary intake with survivors' health status.

METHODS AND STUDY DESIGN

We used data from 6668 participants of a cross-sectional survey taken 3 years (2013) after the disaster. To evaluate combined associations of physical activity and dietary intake, answers to questions regarding these two variables were categorized into four groups: poor physical activity and poor dietary intake (Group 1), poor physical activity and good dietary intake (Group 2), good physical activity and poor dietary intake (Group 3), and good physical activity and good dietary intake (Group 4). Multiple logistic regression analyses were performed by sex, with good self-rated health and good mental health as dependent variables, and age, place of residence, living conditions and physical activity/dietary intake group (with Group 1 as the reference category) as independent variables.

RESULTS

Good self-rated health was associated with age in both sexes, and Groups 3 (male: odds ratios (ORs) 1.84 (95% confidence intervals (95% CIs) 1.32-2.57), female: OR 1.82 (95% CI 1.32-2.51)) and 4 (male: OR 1.96 (95% CI 1.39-2.76), female: OR 1.94 (95% CI 1.42-2.64)). Good mental health was associated with Groups 3 (OR 1.48 (95% CI 1.10-1.97)) and 4 (OR 1.86 (95% CI 1.37-1.97)) for male respondents; and living place (other than temporary housing) (OR 1.45 (95% CI 1.26-1.68)) was associated with Group 4 (OR 1.42 (95% CI 1.09-1.85)) for female respondents.

CONCLUSIONS

Good physical activity alone or combined with good dietary intake was associated with good self-rated health and good mental health. Further interventions regarding physical activity and dietary intake are needed to improve the health status of survivors.

Changes in the effects of living with no siblings or living with grandparents on overweight and obesity in children: Results from a national cohort study in Japan

Effects of living without siblings and living with grandparents on overweight and obesity may change with child's age. We aimed to examine these effects from early childhood to school age at the national level in Japan. Subjects were 43,046 children born in Japan during two weeks in 2001 who were followed annually from 2.5 to 13 years of age in the Longitudinal Survey of Newborns in the 21st Century. We used measured body height and weight reported by participants at each survey and followed the criteria of the International Obesity Task Force to define overweight and obesity. Random-effects logit models by sex, adjusted for time-varying and time-invariant covariates, assessed odds ratios of overweight and obesity for living without siblings and for living with grandparents at each age. The likelihood of overweight and obesity was significantly higher at 8 years and older among children living without siblings, compared with those living with siblings, and odds ratios were highest at 11 years of age in boys (1.87, 95% confidence interval [CI]: 1.49, 2.33) and at 10 and 13 years of age in girls (1.75 [95% CI: 1.36, 2.23] and 1.73 [95% CI: 1.30, 2.31], respectively). It was also significantly higher at 5.5 years and older among children living with grandparents, compared with those living without grandparents, and odds ratios were highest at 10 and 13 years of age in boys (1.53 [95% CI: 1.30, 1.80] and 1.54 [95% CI: 1.27, 1.86], respectively) and at 11 years of age in girls (1.51, 95% CI: 1.24, 1.84). In Japan, living without siblings and living with grandparents may increase the likelihood of overweight and obesity at 8 and 5.5 years and older, respectively. Child's age should be considered during formulation of strategies for prevention of overweight and obesity in these groups.

Different Psychosocial Factors Are Associated With Different Intention and Self-Efficacy Toward Eating Breakfast Among Japanese Breakfast Skippers

A cross-sectional study was conducted among 7593 adults to clarify lifestyle and psychosocial characteristics of breakfast skippers with different intention and self-efficacy toward eating breakfast. Data were obtained from Japan’s national survey in 2009. Multinomial logistic regression analyses were performed to examine the characteristics of each breakfast skipper (having intention and self-efficacy toward eating breakfast [IS], having intention but not self-efficacy [INS], and not having intention to eat breakfast [NI]) compared with breakfast eaters. IS men were less likely to demonstrate understanding of healthy eating. INS and NI men were more likely to eat alone. INS and NI women were less likely to demonstrate understanding of healthy eating. NI men and women were less likely to report weight management behavior. Current smoking and being sleep-deprived were commonly associated with breakfast skipping in both sexes. Our results suggested the need for approaches considering type of breakfast skippers (eg, different intention and self-efficacy).

Effects of rapid aging and lower participation rate among younger adults on the short-term trend of physical activity in the National Health and Nutrition Survey, Japan

AIM

The National Health and Nutrition Survey, Japan, has annually monitored two indicators of physical activity in adults. They are contrasting in the association with age; the prevalence of exercise habit is lower and step counts are higher among younger participants. The present study aimed to examine the effects of rapid aging of the Japanese population and the lower participation rate among younger adults on the short-term trend of two indicators of physical activity using tabulated data.

METHODS

The prevalence of exercise habit and step counts by age groups (≥20 years) from 2003 to 2010 were estimated using tabulated data from the National Health and Nutrition Survey by calculating sex-specific means weighted by age-specific Japanese population data for each year (population-weighted estimates) and for a fixed year (2005; age-standardized estimates). Linear regression analyses were used to test the statistical significance of their trends.

RESULTS

Statistically significant increasing trends in the prevalence of exercise habit were observed for the crude means (P = 0.029), the population-weighted estimates (P = 0.007) and the age-standardized estimates (P = 0.016) only in men. Statistically significant decreasing trends in the step counts were observed for the crude means (P = 0.006 in men and P = 0.033 in women) and the population-weighted estimates (P = 0.008 in men and P = 0.049 in women) both in men and women, but for the age-standardized estimates (P = 0.039) only in men.

CONCLUSIONS

The effects of rapid aging of the Japanese population and the lower participation rate among younger adults on the short-term trend are not small, and age-standardization is necessary to observe even the short-term trend of physical activity data. Geriatr Gerontol Int 2017; 17: 1677-1682.

Personal behaviors including food consumption and mineral supplement use among Japanese adults: a secondary analysis from the National Health and Nutrition Survey, 2003-2010

BACKGROUND AND OBJECTIVES

A daily mineral supplement is useful for those who are at risk of a deficiency. Some Western reports suggest that mineral supplement users have healthy behaviors and are not mineral-deficient. It is unknown whether the same phenomenon is observed in Japan where there is a different dietary culture. The aim of this study was to examine the characteristics of personal behaviors including food consumption nationwide among mineral supplement users from the National Health and Nutrition Survey in Japan 2003-2010.

METHODS AND STUDY DESIGN

Data were obtained from 16,275 adults aged 20-59 years who completed sociodemographic, health status, and 1-day household dietary assessments. Supplement users were compared with non-users. Logistic regression models were utilized to identify the characteristics of food consumption and calcium and iron supplement use, using the medium intake group as a reference.

RESULTS

Overall, 2.1% and 1.4% of adults reported using calcium supplements and iron supplements, respectively. Calcium supplement users were more likely to be physically active, non-smokers, and eat less fat compared with non-users. Furthermore, they were more likely than non-users to consume a higher intake of calcium from foods such as tea, vegetables, seaweeds, and fruits. Iron supplement users were more likely than non-users to be non-smokers. These individuals tended to have a high intake of seaweeds and fruits.

CONCLUSIONS

Japanese adults who had healthier behaviors were more likely to use mineral supplements, especially calcium. Mineral supplement users tended to choose healthy foods such as seaweeds and fruits, without considering their overall mineral consumption.

Associations between Japanese schoolchildren's involvement in at-home meal preparation, their food intakes, and cooking skills

BACKGROUND/OBJECTIVES

This study aimed to examine the association of Japanese schoolchildren's involvement in at-home meal preparation with food intake and cooking skill.

SUBJECTS/METHODS

We included 1,207 fifth-grade children aged 10-11 years and one parent of each child. A cross-sectional survey was used to collect data on involvement in at-home meal preparation. Correspondence analysis was used to classify involvement in at-home meal preparation into three groups: food-related activities (cooking only or with other activities such as shopping, table-setting, clean up, and dishwashing), non-food-related activities (table-setting and/or clean up), and no (helping) activities. Food intake was assessed using a food frequency questionnaire. Logistic regression models were used to examine involvement in at-home meal preparation associations.

RESULTS

The sample consisted of 1,207 fifth-grade children. Vegetable intake was lower in the no (helping) activities group than the food-related activities group (95% CI; boys: 1.2, 5.1, girls: 2.0, 8.9). Fewer children in the non-food-related activities group reported they were able to make a portion of their meals compared with the food-related activities group (95% CI; boys: 1.6, 3.5; girls: 1.5, 3.2).

CONCLUSIONS

Children in the food-related activities group showed more favorable food intake and cooking skills than children in the no (helping) activities or non-food-related activities group.

Relationships between social factors and physical activity among elderly survivors of the Great East Japan earthquake: a cross-sectional study

BACKGROUND

Physical inactivity is a health issue that often occurs after serious disaster. Social factors, which can be disrupted by disaster, are important determinants of physical activity levels in everyday living. This study was designed to confirm the association between social factors and physical activity among elderly survivors of the Great East Japan Earthquake.

METHODS

From September 2011 to February 2012, 4316 males and females aged 65 or older participated in a health survey of Great East Japan Earthquake survivors. Multiple logistic regression analyses were performed with the dichotomous dependent variable of physical activity (high versus low) and working status, social network, and place of residence (one's own home versus elsewhere) as independent variables.

RESULTS

Participants who had been displaced from their homes were more likely to have low physical activity (odds ratio [OR], 95% confidence interval [CI] for men: 1.37, 1.12 to 1.68; for women: 1.30, 1.09 to 1.55). Non-working status was significantly associated with low physical activity (men: 2.03, 1.65 to 2.49; women: 1.94, 1.60 to 2.34). Detriments to the social network were significantly associated with low physical activity (men: 1.71, 1.41 to 2.08; women: 1.79, 1.51 to 2.13).

CONCLUSION

Place of residence and social factors were associated with physical activity levels in elderly survivors of the Great East Japan Earthquake. The findings suggest a need for improvement of social factors to encourage increases in physical activity for elderly persons after disaster.

Association of Energy Intake With the Lack of in-Person Review of Household Dietary Records: Analysis of Japan National Health and Nutrition Surveys From 1997 to 2011

Background

National surveys have demonstrated a long-term decrease in mean energy intake in Japan, despite the absence of a decrease in the prevalence of overweight and obesity. We aimed to examine whether total energy intake of survey respondents is associated with completion of an in-person review of dietary records and whether it affects the trend in mean energy intake.

Methods

We pooled data from individuals aged 20–89 years from the National Nutrition Surveys of 1997–2002 and the National Health and Nutrition Surveys of 2003–2011. We conducted a linear mixed-effects regression to estimate the association between total energy intake and the lack of an in-person review of semi-weighed household dietary records with interviewers. As some respondents did not have their dietary data confirmed, we used regression coefficients to correct their total energy intake.

Results

Compared with respondents completing an in-person review, total energy intake was significantly inversely associated with respondents not completing a review across all sex and age groups (P < 0.001). After correction of total energy intake for those not completing a review, mean energy intake in each survey year significantly increased by 2.1%–3.9% in men and 1.3%–2.6% in women (P < 0.001), but the decreasing trend in mean energy intake was sustained.

Conclusions

Total energy intake may be underestimated without an in-person review of dietary records. Further efforts to facilitate completion of a review may improve accuracy of these data. However, the increasing proportion of respondents missing an in-person review had little impact on the decreasing mean caloric intake.

The longitudinal change in physical activity among Great East Japan Earthquake victims living in temporary housing

OBJECTIVES

This study investigated the longitudinal changes in the physical activity of the Great East Japan Earthquake victims living in temporary housing.

METHODS

Thirty-nine residents (10 men and 29 women) living in temporary housing in Kamaishi City, Iwate Prefecture, participated in a health survey in 2012. Among these residents, 31 who also participated in a health survey in 2011 were included in a longitudinal study of physical activity. The physical activity for two weeks after the health survey was measured using a tri-accelerometer.

RESULTS

During the one-year period from 2011 to 2012, the median daily step counts changed from 4,959 (interquartile range: 2,910-6,029) steps/day to 4,618 (interquartile range: 3,007-7,123) steps/day. The step counts increased for 18 people (56%). The amount of moderate to vigorous physical activity changed from 13.3 (interquartile range: 7.7-22.4) METs h/week to 16.1 (interquartile range: 6.3-25.2) METs h/week. An increase in daily step counts occurred for 14 out of 21 subjects who were <65 years old (67%) and only 3 out of 10 subjects who were ≥65 years old (30%).

CONCLUSION

It was suggested that physical activity levels increased because the interquartile range of step counts moved in the direction of an increase and the median amount of moderate to vigorous physical activity increased. However, increasing support for physical activity in the future is required because the physical activity levels of the Great East Japan Earthquake victims who were living in temporary housing were still low compared to the national and regional averages.

Distribution of vitamin E intake among Japanese dietary supplement and fortified food users: a secondary analysis from the National Health and Nutrition Survey, 2003-2009

This study was performed to: (1) assess the prevalence of dietary supplement and fortified food use, (2) examine the differences in vitamin E intake with and without dietary supplementation and/or fortified food use, and (3) determine whether some individuals consume vitamin E above the tolerable upper intake level (UL). Data were obtained from 64,624 individuals (age, ≥1 y; 47.4% males) who completed a 1-d household dietary assessment that was part of the National Health and Nutrition Survey conducted in Japan, 2003-2009. The survey also obtained information on the brand or generic name of each dietary supplement or fortified food reported, including their ingredients, through dietary assessment. The prevalence of a potential risk of excess was estimated by the proportion of persons above the age-/sex-specific ULs provided by the Dietary Reference Intakes for Japanese 2010. Supplement use was reported by 5.8% of men and 7.7% of women, whereas fortified food consumption was reported by only 2.9% of men and 3.6% of women. Use of dietary supplements was most common among older women, whereas use of fortified foods was most common among younger women. Both dietary supplement and fortified food use accounted for maximum vitamin E intake; however, the use of dietary supplements and fortified foods had little effect on the median and 95th percentile intake values. None of the subjects consumed nutrients above the UL. The collected data confirm that the use of both dietary supplements and fortified foods contributes a small amount to nutrient intake in Japanese subjects.

Dietary intake of nutrients with adequate intake values in the dietary reference intakes for Japanese

The Adequate Intake (AI) values in the Dietary Reference Intakes for Japanese (DRIs-J) 2010 were mainly determined based on the median intakes from 2 y of pooled data (2005-2006) from the National Health and Nutrition Survey-Japan (NHNS-J). However, it remains unclear whether 2 y of pooled data from the NHNS-J are appropriate for evaluating the intake of the population. To clarify the differences in nutrient intakes determined from 2 and 7 y of pooled data, we analyzed selected nutrient intake levels by sex and age groups using NHNS-J data. Intake data were obtained from 64,624 individuals (age: ≥1 y; 47.4% men) who completed a semi-weighed 1-d household dietary record that was part of the NHNS-J conducted annually in Japan from 2003 to 2009. There were no large differences between the median intakes calculated from 2 or 7 y of pooled data for n-6 or n-3 polyunsaturated fatty acids (PUFAs), vitamin D, pantothenic acid, potassium, or phosphorus. When the AI values and median intakes were compared, there was no large difference in the values for n-6 or n-3 PUFAs, pantothenic acid, or phosphorus. Conversely, the AI values for vitamin D and potassium differed from the median intakes of these nutrients for specific sex and age groups, because values were not based on NHNS-J data. Our results indicate that 2 y of pooled data from the NHNS-J adequately reflect the population's intake, and that the current system for determination of AI values will be applicable for future revisions.

[Characteristics of the number of steps in the National Health and Nutrition Survey]

OBJECTIVES

The mean number of steps measured in the National Health and Nutrition Survey is employed for the assessment of physical activity/exercise in "Health Japan 21," and is used to represent the amount of physical activity/exercise that citizens engage in. In this study, we clarified the characteristics of the data on the number of steps, drawn from the National Health and Nutrition Survey.

METHODS

Among the data from the National Health and Nutrition Surveys conducted from 2008 to 2010, data from 21,914 participants on daily number of steps and pedometer attachment were analyzed. On a nutritional intake questionnaire, subjects who responded on the physical status item that they had attached the pedometer all day long were assigned to the "Whole-day-attached" group. Their means, medians, outliers, and frequency distribution were then compared with those in a "Non- whole-day-attached" group.

RESULTS

Subjects assigned to the "Non- whole-day-attached" group accounted for about 8% of cases in 2008, 2009, and 2010. In all three years, the mean number of steps in the "Whole-day-attached" group was 1,076 to 1,472 higher than that in the "Non-whole-day-attached" group. In both groups, outliers were present, and the frequency distribution showed a broad range on the side indicating a higher number of steps. Accordingly, the mean value was higher than the median value by approximately 600 steps.

CONCLUSION

As data on the number of steps measured in the National Health and Nutrition Survey includes individuals not attaching the pedometer all day (approximately 8% of cases), the data are not normally distributed. Therefore, when utilizing these data as representative of citizens' physical activity/exercise, their characteristics should be taken into consideration.

Relationship of living conditions with dietary patterns among survivors of the great East Japan earthquake

Background

During the year after the Great East Japan Earthquake on March 11, 2011, the health conditions and lifestyles of survivors were extensively surveyed. We examined the relationship between living conditions and dietary pattern among survivors.

Methods

A total of 10 466 survivors aged 18 years or older (25% of the population of that age in the area) participated in a survey of Iwate Prefecture. The average frequency of daily consumption of 8 food groups was determined by questionnaire. After excluding staple foods, which were consumed 3 times a day by 85% of participants, factor analysis was performed on 7 food groups among 9789 people (3795 men, 5994 women).

Results

Factor analysis identified 2 dietary patterns—prudent and meat. The prudent dietary pattern is characterized by high intakes of fish and shellfish, soybean products, vegetables, fruit, and dairy products and was more evident among older participants and women. The meat dietary pattern is characterized by high intakes of meat and eggs and was more evident among younger participants and men. Age-adjusted multiple logistic regression analyses showed that male and female current smokers and men and women living in difficult conditions were likely to have a lower prudent dietary pattern score; male current smokers and male daily alcohol drinkers were likely to have a higher meat dietary pattern score.

Conclusions

During the year after the earthquake, the prudent dietary pattern was associated with better living conditions among survivors, whereas the meat dietary pattern was not.

[Validity and reproducibility of a physical activity questionnaire used for health surveying among victims of the Great East Japan Earthquake]

OBJECTIVES

This study was performed to assess the validity and reproducibility of a questionnaire on physical activity status used for health surveying among victims of the Great East Japan Earthquake.

METHODS

Seventy-four residents (21 men and 53 women) living in temporary housing in Kamaishi City, Iwate Prefecture, participated in this study. The physical activity status questionnaire was composed of 4 questions regarding the frequency of performing domestic and occupational physical activities, the frequency of leaving their residence, walking duration per day, and sedentary time. The physical activity level for 2 weeks was measured using a tri-accelerometer to validate the responses to the questionnaire. Test-retest reproducibility was examined at 2-week intervals.

RESULTS

The physical activity levels were 4,521 +/- 2,266 steps/day for men and 4,533 +/- 2,070 steps/day for women. There was a significant difference in step count between those responding differently to the 3 options in the questionnaire regarding average walking duration per day: those who reported walking for > or = 60 min, 30-60 min, or < or = 30 min had step counts of 5,343 +/- 1,757, 4,760 +/- 1,752, and 3,063 +/- 1,772 steps/day, respectively (P < 0.05). When the response options for 3 questions (excluding those for sedentary time) were given scores (a higher score for a higher physical activity level), there were significant correlations between question score and step count (r = 0.486, P < 0.05) and the amount of moderate to vigorous physical activity (r = 0.342, P < 0.05). The test-retest trial showed a moderate degree of reproducibility, with weighted K coefficients of 0.41-0.65.

CONCLUSION

Three questions on physical activity levels may allow assessment of an individual's physical activity level, with a moderate degree of reproducibility.

Serum ferritin is associated with markers of insulin resistance in Japanese men but not in women

OBJECTIVE

Several epidemiological studies have reported that high concentrations of circulating ferritin, a marker of iron stores, are related to insulin resistance (IR); however, questions remain regarding inconsistent data between Asian men and women and the inadequate consideration of potential confounding effects on the relationship between ferritin and IR. Our aim was to examine the relationship between serum ferritin concentrations and IR markers in the Japanese population.

MATERIALS/METHODS

We analyzed data (n=493) from a cross-sectional survey conducted in 2009 among a Japanese working population aged 20-68years. Fasting serum ferritin and insulin levels and fasting plasma glucose levels were determined, and the homeostatic model assessment of IR (HOMA-IR) was calculated. Multiple regression analysis was performed with adjustments for demographic and lifestyle factors, body mass index and serum C-reactive protein.

RESULTS

Fasting insulin and HOMA-IR significantly increased with increasing levels of serum ferritin after adjustment for covariates in men (P for trend=.005 and .001, respectively). Compared with men in the lowest tertile of serum ferritin, those in the highest tertile had a 24% higher HOMA-IR score. Additional data suggested a positive association between iron intake and HOMA-IR (P for trend=.07) in men. Neither serum ferritin nor iron intake was related to IR markers in women, even in postmenopausal women.

CONCLUSIONS

Serum ferritin concentrations were positively associated with fasting insulin and HOMA-IR in men but not in women, suggesting an important role of iron storage in the pathogenesis of IR in Japanese men.

Ionizing radiation exposure and the development of soft-tissue sarcomas in atomic-bomb survivors

BACKGROUND

Very high levels of ionizing radiation exposure have been associated with the development of soft-tissue sarcoma. The effects of lower levels of ionizing radiation on sarcoma development are unknown. This study addressed the role of low to moderately high levels of ionizing radiation exposure in the development of soft-tissue sarcoma.

METHODS

Based on the Life Span Study cohort of Japanese atomic-bomb survivors, 80,180 individuals were prospectively assessed for the development of primary soft-tissue sarcoma. Colon dose in gray (Gy), the excess relative risk, and the excess absolute rate per Gy absorbed ionizing radiation dose were assessed. Subject demographic, age-specific, and survival parameters were evaluated.

RESULTS

One hundred and four soft-tissue sarcomas were identified (mean colon dose = 0.18 Gy), associated with a 39% five-year survival rate. Mean ages at the time of the bombings and sarcoma diagnosis were 26.8 and 63.6 years, respectively. A linear dose-response model with an excess relative risk of 1.01 per Gy (95% confidence interval [CI]: 0.13 to 2.46; p = 0.019) and an excess absolute risk per Gy of 4.3 per 100,000 persons per year (95% CI: 1.1 to 8.9; p = 0.001) were noted in the development of soft-tissue sarcoma.

CONCLUSIONS

This is one of the largest and longest studies (fifty-six years from the time of exposure to the time of follow-up) to assess ionizing radiation effects on the development of soft-tissue sarcoma. This is the first study to suggest that lower levels of ionizing radiation may be associated with the development of soft-tissue sarcoma, with exposure of 1 Gy doubling the risk of soft-tissue sarcoma development (linear dose-response). The five-year survival rate of patients with soft-tissue sarcoma in this population was much lower than that reported elsewhere.

School-based "Shokuiku" program in Japan: application to nutrition education in Asian countries

This paper provides the overview of "Shokuiku" in Japan, and discusses the future perspective on application of its concepts to nutrition education in other Asian countries. In Japan, there has been a growing concern on increase of obesity and the metabolic syndrome among middle-aged men. Additionally, child obesity has also become one of the important health problems. The increased obesity among them is possibly associated with inappropriate dietary habits (eg skipping breakfast, excessive fat intake and insufficient vegetable). Under this circumstance, the "Basic Law on Shokuiku" was enacted in 2005, which was the first law that regulates one's diets and eating habits. For effective implementation of Shokuiku program, dietitians and registered dietitians would play important roles in various settings. Japan has a long history of dietitian system as well as school-lunch programs. Later, in order to further enhance the school-based Shokuiku programs, the Diet and Nutrition Teacher System was established in April 2007. From an international point of view, "nutrition education" programs aim to improve dietary practices so as to ensure adequate energy or nutrient intake and also to reduce obesity and lifestyle-related diseases, whereas the concepts of Shokuiku have very wide approaches. Shokuiku's efforts expand to support food culture, especially through school-based programs, as well as to improve food environment by providing information on appropriate diets. These approaches can be introduced in nutrition education in other Asian countries, not only to improve one's health and nutritional status but also to secure food culture and food safety in each country.

Soy isoflavones for osteoporosis: an evidence-based approach

Effects of soy isoflavones on osteoporosis remain unclear. This review aimed to clarify the effect of soy isoflavones on bone mineral density (BMD) and turnover markers in menopausal women. PubMed and the Cochrane Library were searched in July 2011 for relevant meta-analyses of randomized controlled trials evaluating effects of soy isoflavones on BMD and bone turnover markers. Three meta-analyses evaluated the effects of soy isoflavones on lumbar spine, total hip, femoral neck, and trochanter BMD. Soy isoflavones significantly improved lumbar spine BMD in a moderate manner, but did not affect total hip, femoral neck, and trochanter BMD in menopausal women. Ingestion of soy isoflavones for six months appeared to be enough to exert a beneficial effect on lumbar spine BMD. Two meta-analyses evaluated the effects of soy isoflavones on a bone resorption marker (urine deoxypyridinoline) and two formation markers (serum alkaline phosphatase and osteocalcin). Soy isoflavones significantly decreased urine deoxypyridinoline in a moderate manner, but did not affect serum alkaline phosphatase and osteocalcin in menopausal women. Soy isoflavones may prevent postmenopausal osteoporosis and improve bone strength thus decreasing risk of fracture in menopausal women by increasing lumbar spine BMD and decreasing bone resorption marker urine deoxypyridinoline. Further studies are needed to address factors affecting the magnitude of the beneficial effects of soy isoflavones and to assess the possible interactions between soy isoflavones and anti-osteoporosis drugs, and to verify effects on BMD of other skeletal sites and other bone turnover markers.

Associations of ionizing radiation and breast cancer-related serum hormone and growth factor levels in cancer-free female A-bomb survivors

Levels of exposure to ionizing radiation are increasing for women worldwide due to the widespread use of CT and other radiologic diagnostic modalities. Exposure to ionizing radiation as well as increased levels of estradiol and other sex hormones are acknowledged breast cancer risk factors, but the effects of whole-body radiation on serum hormone levels in cancer-free women are unknown. This study examined whether ionizing radiation exposure is associated with levels of serum hormones and other markers that may mediate radiation-associated breast cancer risk. Serum samples were measured from cancer-free women who attended biennial health examinations with a wide range of past radiation exposure levels (N  =  412, ages 26-79). The women were selected as controls for separate case-control studies from a cohort of A-bomb survivors. Outcome measures included serum levels of total estradiol, bioavailable estradiol, testosterone, progesterone, prolactin, insulin-like growth factor-1 (IGF1), insulin-like growth factor-binding protein 3 (IGFBP-3), and ferritin. Relationships were assessed using repeated-measures regression models fitted with generalized estimating equations. Geometric mean serum levels of total estradiol and bioavailable estradiol increased with 1 Gy of radiation dose among samples collected from postmenopausal women (17%(1Gy), 95% CI: 1%-36% and 21%(1Gy), 95% CI: 4%-40%, respectively), while they decreased in samples collected from premenopausal women (-11%(1Gy), 95% CI: -20%-1% and -12%(1Gy), 95% CI: -20%- -2%, respectively). Interactions by menopausal status were significant (P  =  0.003 and P < 0.001, respectively). Testosterone levels increased with radiation dose in postmenopausal samples (30.0%(1Gy), 95% CI: 13%-49%) while they marginally decreased in premenopausal samples (-10%(1Gy), 95% CI: -19%-0%) and the interaction by menopausal status was significant (P < 0.001). Serum levels of IGF1 increased linearly with radiation dose (11%(1Gy), 95% CI: 2%-18%) and there was a significant interaction by menopausal status (P  =  0.014). Radiation-associated changes in serum levels of estradiol, bioavailable estradiol, testosterone and IGF1 were modified by menopausal status at the time of collection. No associations with radiation were observed in serum levels of progesterone, prolactin, IGFBP-3 or ferritin.

Exposure to ionizing radiation and development of bone sarcoma: new insights based on atomic-bomb survivors of Hiroshima and Nagasaki

BACKGROUND

Radiation-induced bone sarcoma has been associated with high doses of ionizing radiation from therapeutic or occupation-related exposures. However, the development of bone sarcoma following exposure to lower doses of ionizing radiation remains speculative.

METHODS

A cohort analysis based on the Life Span Study (n = 120,321) was performed to assess the development of bone sarcoma in atomic-bomb survivors of Hiroshima and Nagasaki followed from 1958 to 2001. The excess relative risk per gray of ionizing radiation absorbed by the bone marrow was estimated. Additional subject demographic, survival, and clinical factors were evaluated.

RESULTS

Nineteen cases of bone sarcoma (in eleven males and eight females) were identified among the 80,181 subjects who met the inclusion criteria, corresponding to an incidence of 0.9 per 100,000 person-years. The mean ages at the time of the bombing and at diagnosis were 32.4 and 61.6 years, respectively. The mean bone marrow dose was 0.43 Gy. Osteosarcoma was the most commonly identified bone sarcoma. The most common bone sarcoma site was the pelvis. The overall unadjusted five-year survival rate was 25%. A dose threshold was found at 0.85 Gy (95% confidence interval, 0.12 to 1.85 Gy), with a linear dose-response association above this threshold. The linear slope equaled an excess relative risk of 7.5 per Gy (95% confidence interval, 1.34 to 23.14 per Gy) in excess of 0.85 Gy.

CONCLUSIONS

On the basis of what we believe is one of the longest and largest prospective studies assessing the development of bone sarcoma in individuals exposed to ionizing radiation, it appears that the development of radiation-induced bone sarcoma may be associated with exposure to much lower doses of ionizing radiation than have previously been reported. Such new insights may potentially improve bone sarcoma prevention measures and broaden our understanding of the role of ionizing radiation from various sources on the development of malignant tumors. This study stresses the need to become increasingly aware of the various health risks that may be attributable to even low levels of ionizing radiation exposure.

LEVEL OF EVIDENCE

Prognostic Level I. See Instructions to Authors for a complete description of levels of evidence.

Impact of radiation and hepatitis virus infection on risk of hepatocellular carcinoma

In cohort studies of atomic bomb survivors and Mayak nuclear facility workers, radiation-associated increases in liver cancer risk were observed, but hepatitis B virus (HBV) and hepatitis C virus (HCV) infections were not taken strictly into account. We identified 359 hepatocellular carcinoma (HCC) cases between 1970 and 2002 in the cohort of atomic bomb survivors and estimated cumulative incidence of HCC by radiation dose. To investigate contributions of radiation exposure and hepatitis virus infection to HCC risk, we conducted a nested case-control study using sera stored before HCC diagnosis in the longitudinal cohort of atomic bomb survivors. The study included 224 HCC cases and 644 controls that were matched to the cases on gender, age, city, and time and method of serum storage, and countermatched on radiation dose. The cumulative incidence of HCC by follow-up time and age increased significantly with radiation dose. The relative risk (RR) of HCC for radiation at 1 Gy was 1.67 (95% confidence interval: 1.22-2.35) with adjustment for alcohol consumption, body mass index (BMI), and smoking habit, whereas the RRs for HBV or HCV infection alone were 63 (20-241) and 83 (36-231) with such adjustment, respectively. Those estimates changed little when radiation and hepatitis virus infection were fit simultaneously. The RR of non-B, non-C HCC at 1 Gy was 1.90 (1.02-3.92) without adjustment for alcohol consumption, BMI, or smoking habit and 2.74 (1.26-7.04) with such adjustment.

CONCLUSION

These results indicate that radiation exposure and HBV and HCV infection are associated independently with increased HCC risk. In particular, radiation exposure was a significant risk factor for non-B, non-C HCC with no apparent confounding by alcohol consumption, BMI, or smoking habit.