Background: Osteoarthritis (OA) is a leading cause of disability and a source of societal costs among older adults, especially with an increasingly obese population. However, very few published studies have investigated the burden of knee and hip OA due to a high body mass index (BMI). Therefore, this study aimed to systematically summarize the trends of knee and hip OA due to a high BMI in China and the USA between 1990 and 2019.Methods: Data from the Global Burden of Disease Study 2019 were used to estimate the age-standardized prevalence, disability-adjusted life years (DALYs) rates of knee and hip OA, and the burden of knee and hip OA due to a high BMI by sex. Joinpoint regression analysis was used to determine the temporal trend changes in the related DALYs rates of knee and hip OA.Results: The trends in the DALYs rates of knee OA due to a high BMI have shown a steady and large increase in China, while the trends first showed an increase followed by a large decrease near 2001-2005 and finally a steady increase in the USA. The trends in the DALYs rates of hip OA due to a high BMI have shown a steady and large increase in both men and women in China and the USA from 1990 to 2019. For the comparison by age categories from 30 to 34 years to 90–94 years in 2019, the age-standardized DALYs rates due to a high BMI first increased and then decreased after 60–64 years and 70-74 years in both men and women from China and the USA for knee OA, respectively. For hip OA, the age-standardized DALYs rates first increased and then decreased after 70–74 years in both men and women from China and the USA.Conclusions: The burden of knee and hip OA due to a high BMI is substantially increasing in China and the USA in recent years. Researchers and health policy makers should assess the changing patterns of high BMI on the burden of OA and devise corresponding weight-control strategies.

Objectives. Uric acid has been found to be potentially protective in bone metabolism. We investigated the relationship between serum uric acid (sUA) and lumbar bone mineral density (BMD) among 4156 participants aged 60 years and over from the National Health and Nutrition Examination Survey (NHANES). Methods. To estimate the association between sUA and lumbar BMD, multivariate logistic regression analyses were conducted. Fitted smoothing curves and generalized additive models were also performed. Results. We found sUA positively correlated with lumbar BMD after adjusting for other confounders. On subgroup analyses, stratified by sex and race/ethnicity, the positive correlation of sUA with lumbar BMD remained in both men and women, as well as in whites and Mexican Americans, but not in blacks. In blacks, the association of sUA with lumbar BMD was an inverted U-shaped curve (inflection point: 7.5 mg/dL). Conclusions. Our study revealed a positive relationship between sUA and lumbar BMD among most old adults. This association followed an inverted U-shaped curve among blacks.

Background: Calcium and vitamin D play important roles in bone health as essential nutrients. We explored whether serum calcium, 25(OH)D were associated with bone mineral density (BMD) in older adults. Methods: This cross-sectional study was conducted on a sample of 4595 participants (2281 men and 2314 women) aged ≥ 50 years (from 50 to 85 years, 60.1 ± 8.7 years for men and 62.0 ± 9.7 years for women) from the National Health and Nutrition Examination Survey (NHANES) 2001–2006. The independent variables were serum calcium and 25(OH)D. The dependent variable was lumbar BMD. The other variables were considered potential effect modifiers. We performed weighted multivariate linear regression models and smooth curve fittings to evaluate the associations between them. Subgroup analyses were also performed. Results: We observed a negative association between serum calcium and lumbar BMD in the fully adjusted model. In the subgroup analyses, this association was no longer significant among males and other race/ethnicity. On the other hand, there was a positive association between serum 25(OH)D and lumbar BMD in the fully adjusted model. In the subgroup analyses, this association did not differ in different age groups, between men and women. However, the association between serum 25(OH)D and lumbar BMD followed a U-shaped curve in Mexican Americans. Conclusions: This cross-sectional study indicated that serum calcium negatively correlated with lumbar BMD, and serum 25(OH)D positively correlated with lumbar BMD in older adults. However, the association between serum calcium and lumbar BMD in males followed a U-shaped curve.

Background: The organ toxicities of lead and cadmium have been extensively studied; however, studies of their toxic effects on bone remain limited, especially in young adults. The objective of this study was to examine the associations of blood lead levels (BLL) and blood cadmium levels (BCL) with bone mineral density (BMD) among young adults. Methods: We performed a cross-sectional study using the National Health and Nutrition Examination Survey 2011–2018 database. Because of the skewed distribution, BLL and BCL were Ln-transformed for analysis. Weighted multivariate regressions were performed to evaluate the associations between LnBLL and LnBCL and lumbar BMD. Subgroup analyses were further performed. Results: A total of 3234 participants aged 20–35 years were included in this study. No significant association between LnBLL and lumbar BMD was found (β = − 5.6, 95%CI: − 13.5–2.3). However, in the subgroup analysis stratified by sex, this association became negative in women (β = − 18.2, 95%CI: − 29.9– − 6.4). Moreover, this negative association was more prominent in female blacks (β = − 35.5, 95%CI: − 63.4– − 7.6). On the other hand, a negative association between LnBCL and lumbar BMD was found (β = − 7.4, 95%CI: − 14.0– − 0.8). In the subgroup analysis stratified by sex, this negative association only existed in women (β = − 18.7, 95%CI: − 28.0– − 9.5). Moreover, this negative association was more prominent in female whites (β = − 31.1, 95%CI: − 46.2– − 16.1). Conclusions: Our finding showed that both BLL and BCL were independently and negatively associated with lumbar BMD among young females, but not among young males.

Aim: Ensuring adequate calcium (Ca) intake during childhood and adolescence is critical to acquire good peak bone mass to prevent osteoporosis during older age. As one of the primary strategies to build and maintain healthy bones, we aimed to determine whether dietary Ca intake has an influence on bone mineral density (BMD) in children and adolescents. Methods: We conducted a cross-sectional study composed of 10,092 individuals from the National Health and Nutrition Examination Survey (NHANES). Dietary Ca intake and total BMD were taken as independent and dependent variables, respectively. To evaluate the association between them, we conducted weighted multivariate linear regression models and smooth curve fittings. Results: There was a significantly positive association between dietary Ca intake and total BMD. The strongest association was observed in 12–15 year old whites, 8–11 year old and 16–19 year old Mexican Americans, and 16–19 year old individuals from other race/ethnicity, in whom each quintile of Ca intake was increased. We also found that there were significant inflection points in females, blacks, and 12–15 year old adolescents group, which means that their total BMD would decrease when the dietary Ca intake was more than 2.6–2.8 g/d. Conclusions: This cross-sectional study indicated that a considerable proportion of children and adolescents aged 8–19 years would attain greater total BMD if they increased their dietary Ca intake. However, higher dietary Ca intake (more than 2.6–2.8 g/d) is associated with lower total BMD in females, blacks, and 12–15 year old adolescents group.

Background: Obesity and osteoporosis are major public health issues globally. The prevalence of these two diseases prompts the need to better understand the relationship between them. Previous studies, however, have yielded controversial findings on this issue. Therefore, our aim in this study was to evaluate the independent association between waist circumference (WC), as a marker of obesity, and the bone mineral density (BMD) of the lumbar spine among middle-aged adults using data from the National Health and Nutrition Examination Survey (NHANES). Methods: Our analysis was based on NHANES data from 2011 to 2018, including 5084 adults, 40–59 years of age. A weighted multiple linear regression analysis was used to evaluate the association between WC and lumbar BMD, with smooth curve fitting performed for non-linearities. Results: After adjusting for BMI and other potential confounders, WC was negatively associated with lumbar BMD in men (β = −2.8, 95% CI: −4.0 to −1.6) and premenopausal women (β = −2.6, 95% CI: −4.1 to −1.1). On subgroup analysis stratified by BMI, this negative association was more significant in men with a BMI ≥30 kg/m² (β = −4.1, 95% CI: −6.3 to −2.0) and in pre- and postmenopausal women with a BMI <25 kg/m² (premenopausal women: β= −5.7, 95% CI: −9.4 to−2.0; postmenopausal women: β=−5.6, 95% CI: −9.7 to −1.6). We further identified an inverted U-shaped relationship among premenopausal women, with a point of inflection at WC of 80 cm. Conclusions: Our study found an inverse relationship between WC and lumbar BMD in middle-aged men with BMI ≥30 kg/m², and women with BMI <25 kg/m².