Predictive ability of novel volumetric and geometric indices derived from dual-energy X-ray absorptiometric images of the proximal femur for hip fracture compared with conventional areal bone mineral density: the Japanese Population-based Osteoporosis (JPOS) Cohort Study.

Areal BMD (aBMD) from DXA is not a sufficiently accurate predictor of fracture. Novel volumetric BMD derived from 3D modeling of the hip from DXA images significantly improved the predictive ability for hip fracture relative to aBMD at the femoral neck, but not aBMD at the total hip. INTRODUCTION: To clarify whether volumetric and geometric indices derived from novel three-dimensional (3D) modeling of the hip using dual-energy X-ray absorptiometric (DXA) images improve hip fracture prediction relative to areal bone mineral density (aBMD). METHODS: We examined 1331 women who had completed the baseline survey and at least one follow-up survey over 20 years (age 40-79 years at baseline). Each survey included aBMD measurement at the hip by DXA. Volumetric and geometric indices of the hip at baseline and the 10-year follow-up were estimated from DXA images using a 3D modeling algorithm. Incident hip fractures during the 20-year follow-up period were identified through self-report. Cox proportional hazards regression models allowing for repeated measurements of predictors and outcomes were constructed, and their predictive ability for hip fracture was evaluated using areas under receiver operating characteristic curves (AUCs) and net reclassification improvement (NRI) over aBMD at the femoral neck (FN) and total hip (TH) as references. RESULTS: During a median follow-up of 19.8 years, 68 incident hip fractures were identified (2.22/1000 person-years). A significantly larger AUC of trabecular volumetric BMD (vBMD) at the total hip (AUC = 0.741), femoral neck (AUC = 0.748), and intertrochanter (AUC = 0.738) and significant NRI (0.177, 0.149, and 0.195, respectively) were observed compared with FN-aBMD (AUC = 0.701), but not TH-aBMD. CONCLUSIONS: vBMD obtained from 3D modeling using routinely obtained hip DXA images significantly improved hip fracture risk prediction over conventional FN-aBMD, but not TH-aBMD. TRIAL REGISTRATION: The Japanese Population-Based Osteoporosis (JPOS) Cohort Study was retrospectively registered as UMIN000032869 in the UMIN Clinical Trials Registry on July 1, 2018.

Correction to: Age-related normative values of trabecular bone score (TBS) for Japanese women: the Japanese Population-based Osteoporosis (JPOS) study.

I have, as the Principal Investigator of this study, identified an error in the computation of TBS values in the JPOS cohort, which resulted in the publication of incorrect TBS absolute values [1]. This error was linked to the calibration process for calculating standardized TBS values in the R&D TBS.

Total 25-hydroxyvitamin D levels predict fracture risk: results from the 15-year follow-up of the Japanese Population-based Osteoporosis (JPOS) Cohort Study.

We found that community-dwelling women with 25-hydroxyvitamin D levels <20 ng/mL compared to levels ≥20 ng/mL indicated increased risks for clinical, non-vertebral, and fragility fractures during 5 years. Furthermore, the increased risks of non-vertebral fractures remained significant in 10 and 15 years after adjusting for age and bone mineral density. INTRODUCTION: We examined whether total 25-hydroxyvitamin D (25[OH]D) levels are associated with fracture risk over 15 years in a Japanese female cohort. METHODS: Of 1437 community-dwelling women aged ≥50 years in the baseline survey, 1236 provided information regarding fractures during a 15-year follow-up period. The analysis included 1211 women without early menopause or diseases affecting bone metabolism. RESULTS: Over 15 years, 269 clinical (224 non-vertebral, 149 fragility) fracture events were confirmed. Incidence rates categorized by 25(OH)D levels (<10, 10-20, 20-30, and ≥30 ng/mL) indicated a significant divergence for any clinical fractures in 5 years (log rank test p = 0.016) and for non-vertebral fractures in 5, 10, and 15 years (p < 0.001, p = 0.001, p = 0.017, respectively). Hazard ratios (HRs) for 25(OH)D levels <10 and 10-20 ng/mL compared to levels ≥30 ng/mL during 5 years indicated significances for clinical fractures (HR 4.93 with p = 0.009, HR 3.00 with p = 0.034) and for non-vertebral fractures (HR 6.55 with p = 0.005, HR 3.49 with p = 0.036). Those with levels <20 ng/mL compared to those with levels ≥20 ng/mL indicated significant increased risks for clinical fractures (HR 1.72 with p = 0.010), non-vertebral fractures (HR 2.45 with p < 0.001), and fragility fractures (HR 2.00 with p = 0.032) in 5 years. The HR of non-vertebral fractures for levels <20 ng/mL remained significant during 15 years (HR 1.42 with p = 0.012) after adjustment for age and femoral neck bone mineral density. CONCLUSIONS: Low 25(OH)D levels, especially <20 ng/mL, were associated with elevated fracture risks in Japanese women.

Age-related normative values of trabecular bone score (TBS) for Japanese women: the Japanese Population-based Osteoporosis (JPOS) study.

UNLABELLED: Trabecular bone score (TBS), a surrogate measure of bone microarchitecture, represents fracture risk independently of bone density. We present normative TBS values from a representative population study of Japanese women. This database would enhance our understanding of trabecular bone microarchitecture and improve osteoporosis management. INTRODUCTION: TBS is a texture parameter that quantifies local variation in gray level distribution within dual-energy X-ray absorptiometry (DXA) images of the lumbar spine. While TBS is associated with fracture risk independently of areal bone mineral density (aBMD), normative TBS values have only been reported for Caucasian women. This study provides age-specific normative values of TBS from a representative sample of Japanese women. METHODS: We randomly selected 4,550 women aged 15-79 years from 7 areas throughout Japan. Women younger than 20 years and those with any medical history which might affect bone metabolism were excluded, and the remaining 3,069 with at least two assessable vertebrae from the first to the fourth vertebrae were subjected to analysis. TBS values were calculated from spine DXA images using TBS iNsight software (Med-Imaps, France). Age-related models of TBS were constructed using piecewise linear regression analysis. RESULTS: Participant age, body mass index (BMI), spine aBMD, and TBS (mean ± SD) were 48.7 ± 16.8 years, 22.9 ± 3.4, 0.888 ± 0.169 g/cm(2), and 1.187 ± 0.137, respectively. A three-piece linear regression model of TBS on age explained 70.7% of the total variance in TBS and comprised very small age-related changes in the youngest segment of the regression line, rapid loss in the middle segment, and small loss in the oldest segment. TBS was lower in Japanese women than in Caucasian women across all age ranges, with the difference increasing with age up through 65 years. CONCLUSIONS: The normative values of TBS for Japanese women presented here would enhance our understanding of trabecular bone microarchitecture and help improve the management of osteoporosis.

Biochemical markers for bone turnover predict risk of vertebral fractures in postmenopausal women over 10 years: the Japanese Population-based Osteoporosis (JPOS) Cohort Study.

UNLABELLED: We evaluated how bone turnover might predict vertebral fracture risk in postmenopausal women over 10 years. After adjusting for age and femoral neck bone mineral density, high bone-specific alkaline phosphatase and total and free deoxypyridinoline at baseline predicted increased vertebral fracture risk in women with ≥ 5 years since menopause. INTRODUCTION: The aim was to evaluate the ability of bone turnover markers (BTMs) in predicting vertebral fractures. METHODS: Participants in the 1996 baseline survey of the JPOS Cohort Study included 522 postmenopausal women, with no diseases or medications affecting bone metabolism. Vertebral fractures were ascertained in three follow-up surveys (1999, 2002, and 2006). Initial fracture events were diagnosed morphometrically. The Poisson regression model was applied to estimate the rate ratio (RR) of the following log-transformed BTM values at baseline: osteocalcin and bone-specific alkaline phosphatase (BAP) in serum and C-terminal cross-linked telopeptide of type I collagen, total deoxypyridinoline (tDPD), and free deoxypyridinoline (fDPD) in urine. RESULTS: Eighty-three fracture events were diagnosed over a median follow-up period of 10.0 years. RR per standard deviation (SD) (95 % confidence interval) for BAP was 4.38 (1.45, 13.21) among 65 subjects with years since menopause (YSM) < 5 years. RRs per SD (95 % confidence interval) for BAP, tDPD, and fDPD were 1.39 (1.12, 1.74), 1.32 (1.05, 1.67), and 1.40 (1.12, 1.76), respectively, after adjusting for age and femoral neck bone mineral density (FN BMD) among 457 subjects with YSM ≥ 5 years. Of the 451 women followed at least once until 2002, RRs per SD for BAP, tDPD, and fDPD adjusted for age and FN BMD over 6 years were not significantly different from those over 10 years. CONCLUSION: BAP was associated with vertebral fracture risk among early postmenopausal women. BTMs can predict vertebral fractures independently of BMD among late postmenopausal women over a 10-year follow-up period.

Association between Dairy Product intake and Risk of Osteoporotic Fractures in Postmenopausal Japanese Women: Secondary Analysis of 15-Year Follow-Up data from the Japanese Population-Based Osteoporosis (JPOS) Cohort Study.

OBJECTIVES: Few prospective cohort studies have evaluated the relationship between dairy product intake frequency and risk of osteoporotic fractures in Asians. This study aimed to investigate the association between habitual dairy product intake and risk of osteoporotic fractures. DESIGN: Secondary analysis of prospective cohort study. SETTING: Five municipalities of Japan. PARTICIPANTS: This study included 1,429 postmenopausal Japanese women (age ≥45 years at baseline). MEASUREMENTS: Baseline milk-intake frequency was obtained using nurse-administered questionnaires. Intakes of yogurt and cheese, and estimated calcium intake, were assessed using a validated food frequency questionnaire. Osteoporotic fracture was defined as a clinical fracture diagnosed using radiography. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. RESULTS: Over a median follow-up period of 15.1 years (interquartile range [IQR], 10.1-15.4 years; total, 18,118 person-years), 172 women sustained at least one osteoporotic fracture. The proportions of participants with milk intakes <1, 1, and ≥2 cups/d were 34.4%, 48.0%, and 17.6%, respectively. After adjustment for age, frequency of yogurt intake, frequency of cheese intake, body mass index, history of osteoporotic fractures, and frequency of natto intake, the HRs compared with that for milk intake <1 cup/d were 0.71 (95% CI: 0.51-0.98) and 0.57 (95% CI: 0.35-0.92) for 1 cup/d and ≥2 cups/d, respectively. After adjustment for bone mineral density, HR significance for milk intakes ≥2 cups/d remained significant. Yogurt and cheese intakes were not related to the risk of osteoporotic fractures. CONCLUSION: High habitual milk intake, but not a habitual yogurt or cheese intake is associated with a decreased risk of osteoporotic fractures, independent of bone mineral density, in postmenopausal Japanese women.

Association between weight changes and changes in hip geometric indices in the Japanese female population during 10-year follow-up: Japanese Population-based Osteoporosis (JPOS) Cohort Study.

UNLABELLED: During a 10-year follow-up of 893 women of various ages from the Japanese Population-based Osteoporosis Cohort Study, we evaluated the relationship between weight changes and hip geometric strength assessed by hip structure analysis. Our findings suggest that maintaining weight may help retain geometric strength and reduce hip fracture risk. INTRODUCTION: The effects of changes in anthropometric indices on hip geometry in women of various ages are unclear. We evaluated these effects by analyzing 10-year longitudinal data from a representative sample of Japanese women. METHODS: Dual-energy X-ray absorptiometry scans of the proximal femur were performed at baseline and at the 10-year follow-up. Data were analyzed with the Hip Structure Analysis (HSA) program, which yields geometric strength indices including cross-sectional area (CSA), section modulus (SM) and subperiosteal diameter (PD) at regions of interest (ROIs) in the narrow neck (NN), intertrochanter, and femoral shaft (FS) regions. Annual percent change of each HSA index was determined. Height and weight were measured at baseline and follow-up. RESULTS: After excluding subjects with factors affecting bone metabolism, we evaluated 893 women (18-79 years old at baseline). The greatest changes in most HSA indices during the follow-up were observed in subjects aged ≥ 70 years at all ROIs. PD modestly but significantly expanded with age, but this change was not significant in subjects aged ≥ 70 years or those who had entered menopause ≥ 20 years before baseline. An increasing trend in weight was associated with an increase or smaller decline in CSA and SM at the NN and FS regions regardless of menopausal status after adjusting for age, height, and weight at baseline and change of estimated volumetric bone mineral density. Changes in height showed a much weaker association with HSA indices. CONCLUSIONS: Maintaining weight may help retain hip geometric strength and reduce the risk of hip fracture.

Age-specific reference values of hip geometric indices from a representative sample of the Japanese female population: Japanese Population-based Osteoporosis (JPOS) Study.

UNLABELLED: We analyzed 2,107 hip dual-energy X-ray absorptiometry (DXA) images from the Japanese Population-based Osteoporosis Study with the Hip Structure Analysis (HSA) program to obtain age-specific reference values of HSA indices for the Japanese female population. These references may help physicians accurately assess HSA results and aid researchers in making interracial comparisons of the indices. INTRODUCTION: Hip geometry is expected to improve hip fracture risk assessment, which is usually assessed by bone mineral density (BMD) alone. We aimed to establish a reference database for Japanese women. METHODS: We studied 2,107 Japanese women (15-79 years old) with no history of bone metabolism-related diseases from the Japanese Population-based Osteoporosis Study performed in 1996. Hip geometry was conducted on DXA images with the HSA program, which yielded data for cross-sectional area (CSA), subperiosteal diameter (PD), endocortical diameter (ED), mean cortical thickness (CT), section modulus (SM), and buckling ratio at the narrow neck (NN), intertrochanter (IT), and femoral shaft (FS) regions. Mean HSA indices were determined for each 5-year age group after adjustment for height and weight based on most recent Japanese population values. RESULTS: Age-related changes in HSA indices were evident for the 50-54 year group in the NN and IT regions and for the 55-59 year group in the FS region; these changes increased with age thereafter. Age-related changes in CSA and CT were almost identical to that of BMD. Japanese subjects exhibited BMD and CT values similar to those reported for US non-Hispanic white women, but had 16-23% smaller SM values. CSA and CT were highly correlated with conventional BMD, whereas ED, SM, and PD showed lower correlations. CONCLUSIONS: Age-specific reference values of HSA indices for the Japanese female population were obtained. This database will form the foundation for accurate HSA result evaluation.

Fracture risk prediction using FRAX®: a 10-year follow-up survey of the Japanese Population-Based Osteoporosis (JPOS) Cohort Study.

UNLABELLED: We evaluated the predictive ability of FRAX® in a cohort of 815 Japanese women. The observed 10-year fracture rate did not differ significantly from that predicted by FRAX®. The predictive ability of FRAX® without femoral neck bone mineral density (BMD) was similar to that with femoral neck BMD. INTRODUCTION: We evaluated the ability of the Japanese version of FRAX®, a World Health Organization fracture risk assessment tool, to predict the 10-year probability of osteoporotic fracture. METHODS: Self-reported major osteoporotic fracture (N = 43) and hip fracture (N = 4) events were ascertained in the 10-year follow-up survey of the Japanese Population-Based Osteoporosis Cohort Study. Participants were 815 women aged 40-74 years at the baseline survey. Receiver operating characteristic curve analysis compared FRAX® with multiple logistic models based on age, body weight, and femoral neck BMD. RESULTS: The number of observed major osteoporotic or hip fracture events did not differ significantly from the number of events predicted by the FRAX® model (with or without BMD). The area under the curve (AUC) value for FRAX® with BMD for predicting major osteoporotic fractures was similar to that of a logistic model with age, body weight, and BMD (0.69 vs. 0.71, respectively; p = 0.198); the AUC of FRAX® with BMD for predicting hip fractures was similar to that of a model based on age and BMD (0.88 vs. 0.89, respectively; p = 0.164). The AUCs of FRAX® without BMD for predicting major osteoporotic and hip fractures were similar to those with BMD (0.69 vs. 0.67, respectively; p = 0.121; 0.88 vs. 0.86, respectively; p = 0.445). CONCLUSIONS: The Japanese version of FRAX® without BMD estimated the 10-year probability of osteoporotic fracture in this population with few clinical risk factors as similar to that of FRAX® with BMD.

Peroxisome proliferator-activated receptor gamma polymorphism is related to peak bone mass: the JPOS study.

UNLABELLED: We analyzed 1,217 women to examine the effect of peroxisome proliferator-activated receptors gamma (PPARgamma) C161 --> T on bone status. Among 664 premenopausal women, the C161 --> T is associated with low bone mineral density (BMD) at the total hip and femoral neck. Moreover, the odds ratio for osteopenia or osteoporosis at the femoral neck was 1.98 for premenopausal CT/TT genotypes. INTRODUCTION: The impact of PPARgamma on BMD has not been conclusively established. We examined if PPARgamma C161T polymorphism is associated with BMD and its change. METHODS: We conducted a baseline survey in 1996 and a 10-year follow-up survey, Japanese Population-based Osteoporosis Study, with a sample population representative of Japanese women. Of these, 1,217 participants in the 1996 survey were analyzed cross-sectionally, while longitudinal analysis was performed on 563 women. A P value < 0.0042 (=0.05/12 for three menstrual statuses and four skeletal sites) was considered statistically significant after Bonferroni correction in multiple testing for cross-sectional analysis. RESULTS: The total hip and femoral neck BMDs were significantly higher for CC genotype than for CT/TT genotypes among 664 premenopausal women (P = 0.0020, P = 0.0022, respectively). Compared to the CC genotype, the odds ratio for osteopenia or osteoporosis (T-scores below -1) at the femoral neck was 1.98 for premenopausal CT/TT genotypes with statistical significance (P = 0.0041). Change of BMD at either skeletal site during the follow-up period was not significantly different for either menstrual status. CONCLUSIONS: We conclude that the PPARgamma C161T is associated with low peak bone mass.

Prevalent vertebral deformity independently increases incident vertebral fracture risk in middle-aged and elderly Japanese women: the Japanese Population-based Osteoporosis (JPOS) Cohort Study.

SUMMARY: Prevalent vertebral deformity increases incident vertebral fracture risk according to studies focusing primarily on Caucasian elderly populations. We report a 3-fold increase in this risk in a population-based cohort of Japanese women after adjusting for subject propensity for having vertebral deformities. This relationship tended to be stronger in middle-aged women. INTRODUCTION: Evidence on increased risk of incident vertebral fractures associated with vertebral deformity in middle-aged women is limited. We aimed to evaluate this risk in a population-based cohort of Japanese women. METHODS: We followed 712 women aged 50-79 years at baseline randomly selected from 3 municipalities in Japan for 6 years. McCloskey-Kanis criteria identified vertebral deformities on X-ray absorptiometric images. At follow-up, vertebra with > or = 20% height reduction from baseline were considered incident fractures. Rate ratio (RR) of incident fracture for prevalent vertebral deformities was calculated using the Poisson regression equation adjusted for propensity of having vertebral deformities based on potential risk factors. RESULT: Vertebral fractures occurred in 73 women (10.3%). Crude RR of vertebral deformity-associated fracture was 4.63 [95% confidence interval (CI), 3.04-7.04] and decreased to 2.96 (95% CI, 1.77-4.94) after propensity score adjustment. Adjusted RR was generally greater in younger women at 7.19 (95% CI, 1.04-49.6), 3.19 (95% CI, 1.27-7.97), and 2.34 (95% CI, 1.33-4.11) for women aged 50-59, 60-69, and 70-79 years, respectively (p = 0.0527 for those aged 50-59 vs 70-79). CONCLUSION: Vertebral deformity was associated with a 3-fold increase in subsequent vertebral fracture risk in Japanese women, and this association was stronger in middle-aged women.

Work-family conflicts and health behaviors among British, Finnish, and Japanese employees.

BACKGROUND: Work-family conflicts are associated with poor health. However, work-family conflicts and health behaviors have been little studied. PURPOSE: This study examined the associations of conflicts between paid work and family life with unhealthy behaviors among British, Finnish, and Japanese employees. METHOD: Data were derived from postal questionnaire surveys among 40 to 60 years old employees from three cohorts, the British Whitehall II Study (n = 3,397), the Finnish Helsinki Health Study (n = 4,958), and the Japanese Civil Servants Study (n = 2,901). Outcomes were current smoking, heavy drinking, physical inactivity, and unhealthy food habits. Work-family conflicts were measured with eight items. Age, marital status, and occupational class were adjusted for in logistic regression analyses. RESULTS: Work-family conflicts had few and inconsistent associations with unhealthy behaviors in all three cohorts. In the Finnish cohort, strong work-family conflicts were associated with current smoking among men. Women with strong conflicts had more often unhealthy food habits and were more often heavy drinkers than women with weaker conflicts. Likewise, British women with strong work-family conflicts were more often heavy drinkers. CONCLUSION: Although work-family conflicts were fairly prevalent in the examined cohorts, these conflicts had but few associations with the studied key health behaviors.

Mother employment status and nutritional patterns in Japanese junior high schoolchildren.

AIMS: To investigate associations between mothers' employment (full, part time and no employment) and nutrition habits (regularity of breakfast, snack, dinner, meal speed and portion size) in a sample of Japanese junior high schoolchildren, 12-13 years of age. METHODS: A total of 10 453 children aged 12-13 years from the Toyama birth cohort study (fourth phase) participated, of whom 8906 children (89% response rate) responded to all questions related to the examined variables. Nutrition habits consisted of breakfast, snack, dinner, meal speed and meal portion. Children's obesity/overweight was measured by body mass index (BMI). RESULTS: Fathers' employment had no effect on their children's nutrition patterns. Children of full-time employed mothers were the most likely to snack and to skip dinner. Children of part-time employed mothers ate larger meal portions, and those of non-employed mothers reported faster meal speeds. BMI was significantly (P<0.001) higher among children of full-time employed mothers (19.3), and lowest among non-employed mothers (19.00). Children of full-time employed mothers are more likely to be overweight, but not obese compared with other children. CONCLUSION: There was a strong relationship between mother's employment and nutrition patterns in this cohort of Japanese schoolchildren; special programs focused on children's nutrition patterns should take into account the mothers' employment status.

Low bone mass is associated with carotid atherosclerosis in postmenopausal women: the Japanese Population-based Osteoporosis (JPOS) Cohort Study.

UNLABELLED: We analyzed 609 women belonging to the JPOS study in a 10-year follow-up survey, to examine the association of osteoporosis with atherosclerosis. Osteoporosis or prevalent vertebral fracture at baseline was associated with increased intima-media thickness of the carotid bifurcation in postmenopausal women, adjusted for age, BMI, and other variables at baseline. INTRODUCTION: Whether low bone mass predicts increased carotid atherosclerosis has not been fully investigated. METHODS: In 2006, we conducted a 10-year follow-up survey of 1,040 women (follow-up rate: 68.6%). We analyzed 609 women > or =50 years old in 2006 without a history of cardiovascular or connective tissue diseases at baseline. BMD and evaluation of vertebral fracture at baseline were used. The intima-media thickness of carotid bifurcation (BIF-IMT) was measured by B-mode ultrasonography in 2006. RESULTS: Adjusted BIF-IMT values of subjects with spine T-score > or =-1, between-2.5 and -1, and <-2.5 or prevalent vertebral fracture were 1.19 mm, 1.34 mm, 1.57 mm, respectively, in women with less than 10 years since menopause (YSM) (n = 159), 1.30 mm, 1.32 mm, 1.53 mm, in women with YSM > or =10 without a history of hypertension at baseline (n = 144) (both with p < 0.05 for linear trend). Those values among no versus prevalent vertebral fracture in women with YSM > or =10 were 1.40 mm, 1.66 mm with p < 0.05 (n = 202). Those associations were independent of age, BMI, total cholesterol, smoking and drinking habits, history of diabetes mellitus, and hypertension (for women with YSM < 10) at baseline. CONCLUSION: Osteoporosis including prevalent vertebral fracture may be associated with carotid atherosclerosis in the first 10 years of postmenopausal women.

Prolonged exposure to industrial noise causes hearing loss but not high blood pressure: a study of 2124 factory laborers in Japan.

To determine the role of noise exposure in the etiology of hypertension, a cross-sectional study was performed by measuring the blood pressure of 2124 male laborers working in a noisy factory. The prevalence of hypertension was 10.2% in group I (85-115 dB), 10.9% in group II (less than 85 dB) and 12.5% in group III (office workers). There was no difference in systolic or diastolic blood pressure among the three groups. There were 358, 439 and 71 laborers in groups I, II and III, respectively, all having worked in the same noise area for more than 10 years. Blood pressure was lower 10 years previously in each group, but the degree of increment did not significantly differ among the three groups. The prevalence of hearing loss was 16.5% in group I, which was significantly higher than that in group II (7.5%) and group III (2.8%). Blood pressure of laborers with hearing loss was equal to that of laborers with intact hearing acuity. There was no significant relationship between hearing loss and the prevalence of hypertension. Thus, prolonged exposure to industrial noise contributes to hearing loss. However, elevation of blood pressure was not found in laborers working in a noisy factory. This finding was not consistant with previously reported findings in the rat. An adaptability to prolonged noise in man may account for this discrepancy.

Socioeconomic differences in behavioural and biological risk factors: a comparison of a Japanese and an English cohort of employed men.

BACKGROUND: To compare socioeconomic differences in behavioural and biological risk factors in Japanese and English 39-59-year-old employed men. METHODS: We measured systolic and diastolic blood pressure, total and high density lipoprotein (HDL) cholesterol, body mass index (BMI), waist-to-hip ratio and fibrinogen at medical screenings and smoking and alcohol consumption in health questionnaires among Japanese non-manual and manual employees of a steel products company and among English non-manual employees working in Civil Service departments. RESULTS: In England, higher employment grades were advantaged with regard to most risk factors studied. In Japan the picture was different in that higher grades had higher BMI, waist-to-hip-ratio and lower HDL cholesterol. In Japan employment grade differences in these three risk factors are clearly larger among younger men than among older men, while in England age differentials in the grade differences are small. Similar results were obtained for education. CONCLUSIONS: Important differences in the social patterning of risk factors were observed in our cohorts of employed Japanese and English men. The contribution that these risk factors make in explaining social differences in health may vary accordingly. Studies that identify the common and unique determinants of socioeconomic health differences in different populations are needed.

An INTERSALT study investigation: relationship between body mass index and blood pressure in the combined populations of three local centres in Japan.

Body mass index was positively and strongly correlated with BP in the INTERSALT study. Because the average body mass index in Japan, although low relative to other developed countries, has been increasing recently it would be useful, particularly from the public health viewpoint, to investigate the impact of body mass index on BP in Japanese populations. In this study, the relationship between body mass index and BP was investigated taking into account age, alcohol intake and sodium and potassium excretion in 24h urine. Data were obtained from 274 men and 284 women, aged 20-59 years, who were not taking antihypertensive medication. Random selection of participants took place at three local centres as outlined in the 1985 INTERSALT study in Japan. It was found that body mass index was positively and significantly correlated with BP in men and women, respectively, but was independent of age, alcohol intake and urinary sodium/potassium ratio. Both SBP and DBP were significantly higher by > or = 5 mmHg in participants whose body mass index (kg/m2) was in the highest quartile compared with participants in the lowest or the next lowest quartile category in men and women. In this study, it was suggested that the body mass index in Japanese men and women was directly correlated with BP independent of other confounding factors. Accordingly, the maintenance of a moderate body mass index may be important in achieving and maintaining a desirable BP level.

Relationship of parental history of high blood pressure to blood pressure: combined findings of three Japanese population samples, the INTERSALT study.

The relationship of parental history of high blood pressure (HBP) to blood pressure (BP) was estimated in three Japanese population samples, totalling 591 men and women aged 20-59 years, from the INTERSALT study. Parental history of HBP was defined as reported HBP by their father and/or mother. With adjustment for antihypertensive medication, body mass index, alcohol intake, and Na/K ratio in 24-h urine, for participants with a parental history of HBP compared to those without a history, BP was higher for three to four age-sex strata, both for systolic and diastolic pressure (SBP, DBP), by 3.3 to 6.8 and 2.7 to 5.5 mm Hg respectively, with four of these six positive associations statistically significant. This finding was stronger for persons aged 40-59 than for those aged 20-39. These data support the judgment that for persons with a parental history of HBP, BP is apt to increase more with age due to combined effects of genetic and environmental factors. Such people especially need to control their lifestyles carefully, including to maintain an optimal intake of salt (eg, <70 mmol/day) and a high potassium intake, to avoid high alcohol consumption, and keep weight moderate, for the prevention of hypertension.

A cross-sectional study on association of calcium intake with blood pressure in Japanese population.

To investigate the association of calcium intake independently of other nutrients already known as predictors of hypertension, a cross-sectional study was carried out on the same population in Japan as used for the INTERSALT study. Dietary calcium intake was estimated from a 1-day 24-h recall. Sodium and potassium intakes were evaluated by 24-h urinary excretion. Data from 476 subjects aged 20-59 years, 230 men and 246 women, were analysed. The mean dietary calcium intake ranged from 557 to 608 mg/day among men, and from 528 to 639 mg/day among women. Among men, the pooled estimate of the regression coefficients of blood pressure (mm Hg) per 100 mg increase of calcium intake, adjusted for age and body mass index (BMI), were -0.42 mm Hg for systolic blood pressure (SBP) and -0.35 mm Hg for diastolic blood pressure (DBP), but there was no statistical significance. Among women, the pooled estimates of regression coefficients adjusted for age and BMI were -0.92 mm Hg for SBP and -0.83 mm Hg for DBP with statistical significance. After adjustment for age, BMI, alcohol intake and urinary excretion of sodium and potassium, the pooled estimate of calcium intake was -0.66 mm Hg for DBP with statistical significance and -0.70 mm Hg for SBP. A significant negative association of calcium intake with blood pressure was observed among the subjects in Osaka. Our study suggests that increased calcium intake may provide a benefit of lowering blood pressure independently of other minerals such as sodium and potassium.

Urinary sodium and potassium excretion, body mass index, alcohol intake and blood pressure in three Japanese populations.

Standardised data on blood pressure, 24 hour urinary electrolyte excretion and other lifestyle factors were obtained in three Japanese populations as part of the INTERSALT study. Urinary sodium excretion and sodium/potassium ratio were significantly (P less than 0.01) higher in Toyama (a semi-rural area in central Japan) than in Tochigi (a rural area 100 km north of Tokyo) and Osaka. There were also significant (P less than 0.01) differences between the centres in diastolic blood pressure (highest in Toyama), although systolic pressure was similar in all three centres. Average potassium excretion was low (46 mmol/day), and the prevalence of both heavy alcohol drinking (greater than or equal to 300 ml/week) and smoking was high in men (33% and 61% respectively); compared with other countries, there were favourable levels of body mass index (mean 22.4 kg/m2). Despite a recent decline in sodium consumption in Japan, which has been accompanied by a fall in blood pressure levels, in the prevalence of hypertension and also in stroke mortality, average sodium excretion in the three centres was high compared to other countries (187 mmol/day). Applying overall INTERSALT regression coefficients to the Japanese data, suggested that further falls in sodium intake together with a modest increase in potassium intake and a reduction (in men) in the prevalence of heavy alcohol drinking could have an important impact on average blood pressures and the prevalence of hypertension. It can be expected that these nonpharmacological approaches to improved blood pressure levels will be accompanied by continued reductions in mortality from stroke.