- Browse by Author
Browsing by Author "Xia, Jin"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Associations Between Vitamin D Biomarkers and Cardiometabolic Outcomes Among Women(2020-02) Xia, Jin; Song, Yiqing; Nan, Hongmei; Tu, Wanzhu; Han, JialiThere is growing evidence that vitamin D endocrine system may be associated with multiple cardiometabolic outcomes, such as gestational diabetes mellitus (GDM), type 2 diabetes, and other relevant cardiometabolic comorbidities, as well as some intermediate cardiometabolic biomarkers. African Americans tend to have lower 25-hydroxyvitamin D[25(OH)D] levels and higher cardiometabolic risk than whites. However, the temporal relation between vitamin D status and cardiometabolic outcomes remains unclear due to the lack of longitudinal data. Further, whether adding information on parathyroid hormone (PTH) can explain black-white disparities in cardiometabolic health is unknown. In this dissertation, I first prospectively and longitudinally investigated vitamin D status during early to mid-pregnancy in relation to GDM risk in a multiracial cohort of women from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singleton cohort. I also analyzed the data from the Women’s Health Initiative-Observational Study to 1) cross-sectionally examine race (black-white)-specific linear and non-linear relations of 25(OH)D and PTH with a panel of cardiometabolic biomarkers, including high-sensitive C-reactive protein, estimated glomerular filtration rate, and homeostatic model assessment of insulin resistance and beta-cell function, and 2) cross-sectionally and prospectively evaluate the combined associations of 25(OH)D and PTH with risk of diabetes and related cardiometabolic comorbidities (obesity, hypertension, chronic kidney disease, and cardiovascular disease) in U.S. white and black postmenopausal women. This research provides evidence of the temporal association between vitamin D status and cardiometabolic risk among women from racially/ethnically diverse groups, and possible black-white differences in these associations. The findings enhance our understanding of the contribution of vitamin D-PTH endocrine system to racial disparities in cardiometabolic health.Item Associations of Muscle Mass and Strength with All-Cause Mortality among US Older Adults(Lippincott, Williams & Wilkins, 2018-03) Li, Ran; Xia, Jin; Zhang, Xi; Gathirua-Mwangi, Wambui Grace; Guo, Jianjun; Li, Yufeng; McKenzie, Steve; Song, Yiqing; Epidemiology, School of Public HealthINTRODUCTION: Recent studies suggested that muscle mass and muscle strength may independently or synergistically affect aging-related health outcomes in older adults; however, prospective data on mortality in the general population are sparse. METHODS: We aimed to prospectively examine individual and joint associations of low muscle mass and low muscle strength with all-cause mortality in a nationally representative sample. This study included 4449 participants age 50 yr and older from the National Health and Nutrition Examination Survey 1999 to 2002 with public use 2011 linked mortality files. Weighted multivariable logistic regression models were adjusted for age, sex, race, body mass index (BMI), smoking, alcohol use, education, leisure time physical activity, sedentary time, and comorbid diseases. RESULTS: Overall, the prevalence of low muscle mass was 23.1% defined by appendicular lean mass (ALM) and 17.0% defined by ALM/BMI, and the prevalence of low muscle strength was 19.4%. In the joint analyses, all-cause mortality was significantly higher among individuals with low muscle strength, whether they had low muscle mass (odds ratio [OR], 2.03; 95% confidence interval [CI], 1.27-3.24 for ALM; OR, 2.53; 95% CI, 1.64-3.88 for ALM/BMI) or not (OR, 2.66; 95% CI, 1.53-4.62 for ALM; OR, 2.17; 95% CI, 1.29-3.64 for ALM/BMI). In addition, the significant associations between low muscle strength and all-cause mortality persisted across different levels of metabolic syndrome, sedentary time, and LTPA. CONCLUSIONS: Low muscle strength was independently associated with elevated risk of all-cause mortality, regardless of muscle mass, metabolic syndrome, sedentary time, or LTPA among US older adults, indicating the importance of muscle strength in predicting aging-related health outcomes in older adults.Item Combined associations of 25-hydroxivitamin D and parathyroid hormone with diabetes risk and associated comorbidities among U.S. white and black women(Springer Nature, 2021-09) Xia, Jin; Tu, Wanzhu; Manson, JoAnn E.; Nan, Hongmei; Shadyab, Aladdin H.; Bea, Jennifer W.; Gower, Emily W.; Qi, Lihong; Cheng, Ting-Yuan David; Song, Yiqing; Epidemiology, School of Public HealthBackground/objectives: There is evidence of black-white differences in vitamin D status and cardiometabolic health. This study aimed to further evaluate the joint associations of 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) with risks of diabetes and related cardiometabolic comorbidities among white and black women. Subjects/methods: We cross-sectionally and prospectively analyzed data from 1850 black and 3000 white postmenopausal women without cardiovascular disease or dialysis at baseline from the Women's Health Initiative-Observational Study. Weighted Cox proportional hazards analyses and weighted logistic regression models were used to examine the joint associations of 25(OH)D and PTH with incident diabetes and prevalence of other diabetes-related cardiometabolic comorbidities (including CKD, hypertension, or obesity). Results: We identified 3322 cases of obesity (n = 1629), hypertension (n = 2759), or CKD (n = 318) at baseline and 453 incident cases of diabetes during 11 years of follow-up. Cross-sectionally, lower 25(OH)D and higher PTH were independently associated with higher prevalence of hypertension [odds ratio (OR) = 0.79; 95% confidence interval (CI): 0.72-0.87 and OR = 1.55; 95% CI: 1.39-1.73] among white women only. When stratified by diabetes status, compared to women with 25(OH)D ≥50 nmol/L and PTH ≤6.89 pmol/L (65 pg/mL), women who did not have diabetes with vitamin D deficiency (<50 nmol/L) and PTH excess (>6.89 pmol/L) had higher prevalence of CKD, hypertension, or obesity (OR = 4.23; 95% CI: 2.90-6.18) than women who had diabetes (OR = 1.89; 95% CI: 0.96-3.71). Prospectively, lower 25(OH)D was associated with lower diabetes incidence [hazard ratio (HR) = 0.73; 95% CI: 0.62-0.86] in white women. Jointly, compared to the group with 25(OH)D ≥50 nmol/L and PTH ≤6.89 pmol/L, white women with 25(OH)D deficiency (<50 nmol/L) had elevated risk for diabetes, regardless of PTH levels. Conclusions: Low 25(OH)D and high PTH were jointly associated with increased risk of diabetes among white women only. Their joint associations with high prevalence of CKD, hypertension, and obesity were more pronounced among women without diabetes.Item Race-specific associations of 25-hydroxyvitamin D and parathyroid hormone with cardiometabolic biomarkers among US white and black postmenopausal women(Elsevier, 2020-08-01) Xia, Jin; Tu, Wanzhu; Manson, JoAnn E.; Nan, Hongmei; Shadyab, Aladdin H.; Bea, Jennifer W.; Cheng, Ting-Yuan D.; Hou, Lifang; Song, Yiqing; Epidemiology, School of Public HealthBackground: Concentrations of 25-hydroxyvitamin D [25(OH)D] tend to be lower in African Americans than in non-Hispanic whites, but whether adding information on parathyroid hormone (PTH) can help explain the higher cardiometabolic risk among African Americans is unknown. Objectives: This study examined race (black/white)-specific independent and joint associations of 25(OH)D and PTH with cardiometabolic biomarkers including high-sensitivity C-reactive protein (hs-CRP), estimated glomerular filtration rate (eGFR), and homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-B). Methods: Among 1500 white and 1300 black postmenopausal women without cardiovascular disease from the Women's Health Initiative Observational Study, a weighted linear regression analysis and a novel penalized spline-based semiparametric model with contour plots, accounting for possible nonlinear relations and interactions simultaneously, were used to investigate the race-specific independent and joint associations of 25(OH)D and PTH with each biomarker. Results: Black women had lower concentrations of 25(OH)D and higher PTH, HOMA-IR, HOMA-B, hs-CRP, and eGFR than white women (all P values < 0.0001). Lower 25(OH)D and higher PTH were each independently and jointly associated with higher HOMA-IR in both white and black women, whereas a similar joint relation with HOMA-B was observed in white women only. In contrast, PTH was nonlinearly associated with HOMA-B in black women and positively associated with hs-CRP in white women, independently of 25(OH)D. Whereas there was an inverse linear relation between PTH and eGFR in white women after accounting for 25(OH)D, PTH and 25(OH)D were jointly and nonlinearly associated with eGFR in black women. Conclusions: We found that the joint association of 25(OH)D and PTH with β-cell function, systemic inflammation, and kidney function apparently differed between white and black women. Further studies are needed to determine whether differences in the vitamin D-PTH endocrine system contribute to racial disparities in cardiovascular health.Item Serum Magnesium Concentrations and All-cause, Cardiovascular, and Cancer Mortality among U.S. Adults: Results from The NHANES I Epidemiologic Follow-up Study(Elsevier, 2017) Zhang, Xi; Xia, Jin; Del Gobbo, Liana C.; Hruby, Adela; Dai, Qi; Song, Yiqing; Epidemiology, School of Public HealthBackground Few studies have examined the associations of serum magnesium (Mg) concentrations with total and cause-specific mortality in a nationally representative sample of US adults. We investigate the dose–response relationships of baseline serum Mg concentrations with risk of mortalities in a large, nationally representative sample of US adults. Methods We analyzed prospective data of 14,353 participants aged 25–74 years with measures of serum Mg concentrations at baseline (1971–1975) from the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (NHEFS). Mortality data was linked through December 31, 2011. We estimated the mortality hazard ratios (HRs), for participants within serum Mg categories of <0.7, 0.7–0.74, 0.75–0.79, 0.8–0.89 (referent), 0.9–0.94, 0.95–0.99, and ≥1.0 mmol/L using weighted multivariate-adjusted Cox proportional hazards models. Results During a median follow-up of 28.6 years, 9012 deaths occurred, including 3959 CVD deaths, 1923 cancer deaths, and 708 stroke deaths. The multivariate-adjusted HRs (95% CIs) of all-cause mortality across increasing categories of Mg were 1.34 (1.02, 1.77), 0.94 (0.75, 1.18), 1.08 (0.97, 1.19), 1.00 (referent), 1.05 (0.95, 1.16), 0.96 (0.79, 1.15), and 0.98 (0.76, 1.26). Similar trends were observed for cancer (HRs for serum Mg < 0.7: 1.39, 95% CI: 0.83, 2.32) and CVD mortality (HRs for serum Mg < 0.7: 1.28, 95% CI: 0.81, 2.02) but were not statistically significant. An elevated risk for stroke mortality was observed among participants with serum Mg < 0.70 mmol/L (HR: 2.55, 95% CI: 1.18, 5.48). Conclusions Very low serum Mg concentrations were significantly associated with an increased risk of all-cause mortality in US adults.Item Vitamin D Status during Pregnancy and the Risk of Gestational Diabetes Mellitus: A Longitudinal Study in a Multiracial Cohort(Wiley, 2019) Xia, Jin; Song, Yiqing; Rawal, Shristi; Wu, Jing; Hinkle, Stefanie N.; Tsai, Michael Y.; Zhang, Cuilin; Epidemiology, School of Public HealthAims Emerging evidence suggests that maternal vitamin D status may be associated with gestational diabetes (GDM). However, the temporal relation remains unclear due to the lack of longitudinal data on vitamin D over pregnancy. We aimed to prospectively and longitudinally investigate vitamin D status during early to mid‐pregnancy in relation to GDM risk. Methods In a nested case‐control study of 107 GDM cases and 214 controls within the Fetal Growth Studies‐Singleton Cohort, plasma levels of 25‐hydroxyvitamin D2 and D3 (25(OH)D) and vitamin D binding protein were measured at gestational weeks 10‐14, 15‐26, 23‐31, and 33‐39; we further calculated total, free, and bioavailable 25(OH)D. Conditional logistic regression models and linear mixed‐effects models were used. Results We observed a threshold effect for the relation of vitamin D biomarkers with GDM risk. Vitamin D deficiency (<50 nmol/L) at 10‐14 gestational weeks was associated with a 2.82‐fold increased risk for GDM [odds ratio (OR) =2.82, 95% confidence interval (CI): 1.15‐6.93]. Women with persistent vitamin D deficiency at 10‐14 and 15‐26 weeks of gestation had a 4.46‐fold elevated risk for GDM compared to women persistently non‐deficient (OR=4.46, 95% CI: 1.15‐17.3). Conclusions Maternal vitamin D deficiency as early as the first trimester of pregnancy was associated with an elevated risk of GDM. The association was stronger for women who were persistently deficient through the 2nd trimester. Assessment of vitamin D status in early pregnancy may be clinically important and valuable for improving risk stratification and developing effective interventions for the primary prevention of GDM.