Xiaoguang Ma

BMI and Risk of Serious Upper Body Injury Following Motor Vehicle Crashes: Concordance of Real-World and Computer-Simulated Observations

Shankuan Zhu and colleagues use computer crash simulations, as well as real-world data, to evaluate whether driver obesity is associated with greater risk of body injury in motor vehicle crashes.

Association between sleep duration and bone mineral density in Chinese women

BACKGROUND Short sleep duration has been found to be closely related to several endocrine and metabolic dysfunctions. However, evidence of the association between insufficient sleep and bone health was limited. OBJECTIVE The present study was aimed to examine the relationships between sleep duration and bone mineral density (BMD) in Chinese women. METHODS Six hundred and two women aged 18-80 years were analyzed. Sleep duration was collapsed to form categories of 5h or less, 6h, 7h, 8h, and 9h or more. Total and regional BMD were measured using dual-energy X-ray absorptiometry. Multiple regression analysis was performed to examine the relationships between sleep duration categories and BMD. RESULTS Women with a short sleeping duration were more likely to have lower total and all body regional BMD after adjusting for potential covariates (all p values for trend <0.05). Compared to those who slept 8h, individuals who slept 5h or less and 6h had significant lower total and regional BMD (β coefficients ranged -0.07 to -0.11, all p<0.05). When further divided women into 18-44 years old and 45 years or older groups, and reran the regression models, the significant associations between BMD and sleep duration were only observed in 45 years or older group. CONCLUSIONS Significant variations in total and regional BMD with sleep duration were observed in women. Decreased sleep duration closely associated with lower BMD, especially in middle-age and elderly women. These findings may lead to the development of better preventive approaches to osteoporosis in women through identification of potential modifiable risk factors.

Lower BMI cutoffs to define overweight and obesity in China

To investigate ethnic difference in the associations of BMI with comorbidity, mortality, and body composition between mainland Chinese and U.S. whites.

Obesity and Non-fatal Motor Vehicle Crash Injuries: Sex Difference Effects

Background:Obesity and motor vehicle crash (MVC) injuries are two parallel epidemics in the United States. An important unanswered question is whether there are sex differences in the associations between the presence of obesity and non-fatal MVC injuries.Objectives:To further understand the association between obesity and non-fatal MVC injuries, particularly the sex differences in these relations.Methods:We examined this question by analyzing data from the 2003 to 2007 National Automotive Sampling System Crashworthiness Data System (NASS CDS). A total of 10 962 drivers who were aged 18 years or older and who survived frontal collision crashes were eligible for the study.Results:Male drivers experienced a lower rate of overall non-fatal MVC injuries than did female drivers (38.1 versus 52.2%), but experienced a higher rate of severe injuries (0.7 versus 0.2%). After adjusting for change in velocity (ΔV) during the crashes, obese male drivers showed a much higher risk (logistic coefficients of body mass index (BMI) for moderate, serious and severe injury are 0.0766, 0.1470 and 0.1792, respectively; all P<0.05) of non-fatal injuries than did non-obese male drivers and these risks increased with injury severity. Non-fatal injury risks were not found to be increased in obese female drivers. The association between obesity and risk of non-fatal injury was much stronger for male drivers than for female drivers.Conclusion:The higher risk of non-fatal MVC injuries in obese male drivers might result from their different body shape and fat distribution compared with obese female drivers. Our findings should be considered for obesity reduction, traffic safety evaluation and vehicle design for obese male drivers and provide testable hypotheses for future studies.

Association of regional body fat with metabolic risks in Chinese women.

OBJECTIVE To investigate the association of regional fat depots with metabolic risk factors in Chinese women. DESIGN Total and regional fat depots including android fat and gynoid fat were measured by dual-energy X-ray absorptiometry. Central fat distribution was defined as android:gynoid fat ratio. Metabolic risk factors were defined as elevated TAG, reduced HDL-cholesterol, elevated blood pressure and elevated fasting plasma glucose. Logistic regression analyses were performed to examine the associations of regional fat depots with metabolic risk factors. The odds ratios of metabolic risks were further calculated according to tertiles of android fat and gynoid fat. SETTING Participants were recruited from a community-based cross-sectional study. Face-to-face questionnaires, anthropometric and dual-energy X-ray absorptiometry measures were conducted. SUBJECTS Chinese women (n 609) aged 18-79 years. RESULTS Android fat and android:gynoid fat ratio were associated with significantly increased odds (OR = 1·4-3·7; P < 0·01) for almost all risk factors, whereas gynoid fat was independently associated with significantly decreased odds (OR = 0·3-0·6; P < 0·01). The inverse associations of gynoid fat with metabolic risk factors remained after adjusting for android fat. Even if their android fat level was in high, women in the highest tertile of gynoid fat had lower odds of having at least two metabolic risk factors compared with women in the lowest gynoid fat tertile (P for trend < 0·01). CONCLUSIONS There were opposite associations of android and gynoid fat with metabolic risks in Chinese women. Gynoid fat rather than android fat might be a more important inclusion in metabolic disease risk evaluation in female Asians.

Actinic Skin Damage and Mortality - the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study

Background Exposure to sunlight may decrease the risk of several diseases through the synthesis of vitamin D, whereas solar radiation is the main cause of some skin and eye diseases. However, to the best of our knowledge, the association of sun-induced skin damage with mortality remains unknown. Methodology/Principal Findings Subjects were 8472 white participants aged 25–74 years in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. Cardiovascular disease mortality, cancer mortality, and all-cause mortality were obtained by either a death certificate or a proxy interview, or both. Actinic skin damage was examined and recorded by the presence and severity (absent, minimal, moderate, or severe) of overall actinic skin damage and its components (i.e., fine telangiectasia, solar elastosis, and actinic keratoses). Cox regression and Kaplan-Meier methods were applied to explore the associations. A total of 672 cancer deaths, 1500 cardiovascular disease deaths, and 2969 deaths from all causes were documented through the follow-up between 1971 and 1992. After controlling for potential confounding variables, severe overall actinic skin damage was associated with a 45% higher risk for all-cause mortality (95% CI: 1.22, 1.72; P<0.001), moderate overall skin damage with a 20% higher risk (95% CI: 1.08., 1.32; P<0.001), and minimal overall skin damage with no significant mortality difference, when compared to those with no skin damage. Similar results were obtained for all-cause mortality with fine telangiectasia, solar elastosis, and actinic keratoses. The results were similar for cancer and cardiovascular disease mortality. Conclusions The present study gives an indication of an association of actinic skin damage with cardiovascular disease, cancer and all-cause mortality in white subjects. Given the lack of support in the scientific literature and potential unmeasured confounding factors, this finding should be interpreted with caution. More independent studies are needed before any practical recommendations can be made.

Effectiveness of booster seats compared with no restraint or seat belt alone for crash injury prevention

OBJECTIVES The objective was to evaluate the effectiveness of belt-positioning booster seats, compared with no restraint use and with seat belt use only, during motor vehicle crashes among U.S. children. METHODS This was a retrospective matched cohort study with data from the 1998 through 2009 National Automotive Sampling System (NASS) Crashworthiness Data System (CDS). The study sample consisted of children aged 0 to 10 years who were not seated in the front seat of the vehicle. We used Cox proportional hazards models to estimate the risk of overall, fatal, and regional body injury. RESULTS Children using seat belts in belt-positioning booster seats experienced less overall injury (Injury Severity Score [ISS] > 0, adjusted risk ratio [RR] = 0.73, 95% confidence interval [CI] = 0.55 to 0.96; Abbreviated Injury Scale [AIS] score of 2 or higher, adjusted RR = 0.30, 95% CI = 0.16 to 0.58; ISS > 8, adjusted RR = 0.19, 95% CI = 0.06 to 0.56), and less injury in most body regions except the neck (adjusted RR = 4.79, 95% CI = 1.43 to 16.00) than did children with no restraint use. Children using seat belts in belt-positioning booster seats had an equal risk of injury but higher risks of neck (adjusted RR = 1.86, 95% CI = 1.02 to 3.40) and thorax (adjusted RR = 2.86, 95% CI = 1.33 to 6.15) injury than did children restrained by seat belts only. CONCLUSIONS Children using belt-positioning booster seats appear to experience a higher risk of AIS > 0 injury to the neck and thorax than do children using seat belts only. Future research should examine whether the observed increase in neck and thorax injuries can be attributed to improper use of booster seats.

A computational study of injury severity and pattern sustained by overweight drivers in frontal motor vehicle crashes

The objective of this study was to examine the role of body mass and subcutaneous fat in injury severity and pattern sustained by overweight drivers. Finite element models were created to represent the geometry and properties of subcutaneous adipose tissue in the torso with data obtained from reconstructed magnetic resonance imaging data-sets. The torso adipose tissue models were then integrated into the standard multibody dummy models together with increased inertial parameters and sizes of the limbs to represent overweight occupants. Frontal crash simulations were carried out considering a variety of occupant restraint systems and regional body injuries were measured. The results revealed that differences in body mass and fat distribution have an impact on injury severity and pattern. Even though the torso adipose tissue of overweight subjects contributed to reduce abdominal injury, the momentum effect of a greater body mass of overweight subjects was more dominant over the cushion effect of the adipose tissue, increasing risk of other regional body injuries except abdomen. Through statistical analysis of the results, strong correlations (p < 0.01) were found between body mass index and regional body injuries except neck injury. The analysis also revealed that a greater momentum of overweight males leads to greater forward torso and pelvic excursions that account for higher risks (p < 0.001) of head, thorax and lower extremity injury than observed in non-overweight males. The findings have important implications for improving the vehicle and occupant safety systems designed for the increasing global obese population.

Fat and Fat Distribution in Menopause: Chinese Aspects

Available studies on body fat distribution and menopause suggest that menopause is associated • with an acceleration in the accumulation of abdominal adipose tissue, and most likely, intraabdominal fat. This trend toward central obesity favors increased cardiovascular, cancer, and metabolic risks, and • may partially mediate the increased morbidity and mortality after menopause. Compared with other races and ethnic groups, Asians such as Chinese, Japanese, and Singaporeans • were reported to be with lower BMI but with higher percent body fat and more abdominal fat at any given level of BMI. Chinese women undergoing menopausal transition and postmenopausal women were associated • with decreased lean mass, and increased percent body fat, trunk fat mass, and trunk–leg fat mass ratio comparing with women remained premenopausal. Limited evidence identi fi ed the effect of menopause on fat distribution among Chinese women; • however, more research was needed to con fi rm the fi ndings with longitudinal design, larger sample size, and more advanced measuring technologies.