1.
Racial/Ethnic Differences in 25-Hydroxy Vitamin D and Parathyroid Hormone Levels and Cardiovascular Disease Risk Among Postmenopausal Women.
Zhang, X, Tu, W, Manson, JE, Tinker, L, Liu, S, Cauley, JA, Qi, L, Mouton, C, Martin, LW, Hou, L, et al
Journal of the American Heart Association. 2019;(4):e011021
Abstract
Background Recent evidence suggests that racial/ethnic differences in circulating levels of free or bioavailable 25-hydroxy vitamin D (25[ OH ]D) rather than total 25( OH )D may explain apparent racial disparities in cardiovascular disease ( CVD ). We prospectively examined black-white differences in the associations of total, free, and bioavailable 25( OH )D, vitamin D-binding protein, and parathyroid hormone levels at baseline with incident CVD (including nonfatal myocardial infarction, nonfatal stroke, and CVD death) in postmenopausal women. Methods and Results We conducted a case-cohort study among 79 705 postmenopausal women, aged 50 to 79 years, who were free of CVD at baseline in the WHI-OS (Women's Health Initiative Observational Study). A subcohort of 1300 black and 1500 white participants were randomly chosen as controls; a total of 550 black and 1500 white women who developed incident CVD during a mean follow-up of 11 years were chosen as cases. We directly measured total 25( OH )D, vitamin D-binding protein, albumin, parathyroid hormone, and calculated free and bioavailable 25( OH )D. Weighted Cox proportional hazards models were used to examine their associations with CVD risk. Although vitamin D-binding protein and total, free, and bioavailable 25( OH )D were not significantly associated with CVD risk in black or white women, a significant positive association between parathyroid hormone and CVD risk persisted in white women (hazard ratio comparing the highest quartile with the lowest, 1.37; 95% CI , 1.06-1.77) but not in black women (hazard ratio comparing the highest quartile with the lowest, 1.12; 95% CI, 0.79-1.58), independent of total, free, and bioavailable 25( OH )D or vitamin D-binding protein. Conclusions Circulating levels of vitamin D biomarkers are not related to CVD risk in either white or black women. Higher parathyroid hormone levels may be an independent risk factor for CVD in white women.
2.
Evaluation of the Pooled Cohort Risk Equations for Cardiovascular Risk Prediction in a Multiethnic Cohort From the Women's Health Initiative.
Mora, S, Wenger, NK, Cook, NR, Liu, J, Howard, BV, Limacher, MC, Liu, S, Margolis, KL, Martin, LW, Paynter, NP, et al
JAMA internal medicine. 2018;(9):1231-1240
-
-
Free full text
-
Abstract
IMPORTANCE Atherosclerotic cardiovascular disease (ASCVD) kills approximately 1 in every 3 US women. Current cholesterol, hypertension, and aspirin guidelines recommend calculating 10-year risk of ASCVD using the 2013 Pooled Cohort Equations (PCE). However, numerous studies have reported apparent overestimation of risk with the PCE, and reasons for overestimation are unclear. OBJECTIVE We evaluated the predictive accuracy of the PCE in the Women's Health Initiative (WHI), a multiethnic cohort of contemporary US postmenopausal women. We evaluated the effects of time-varying treatments such as aspirin and statins, and ascertainment of additional ASCVD events by linkage with the Centers for Medicare and Medicaid Services (CMS) claims. DESIGN, SETTING, AND PARTICIPANTS The WHI recruited the largest number of US women (n = 161 808) with the racial/ethnic, geographic, and age diversity of the general population (1993-1998). For this study, we included women aged 50 to 79 (n = 19 995) participating in the WHI with data on the risk equation variables at baseline and who met the guideline inclusion and exclusion criteria. Median follow-up was 10 years. MAIN OUTCOMES AND MEASURES For this study, ASCVD was defined as myocardial infarction, stroke, or cardiovascular death. RESULTS Among the 19 995 women (mean [SD] age, 64 [7.3] years; 8305 [41.5%] white, 7688 [38.5%] black, 3491 [17.5%] Hispanic, 103 [0.5%] American Indian, 321 [1.6%] Asian/Pacific Islander, and 87 [0.4%] other/unknown), a total of 1236 ASCVD events occurred in 10 years and were adjudicated through medical record review by WHI investigators. The WHI-adjudicated observed risks were lower than predicted. The observed (predicted) risks for baseline 10-year risk categories less than 5%, 5% to less than 7.5%, 7.5% to less than 10%, and 10% or more were 1.7 (2.8), 4.4 (6.2), 5.3 (8.7), and 12.4 (18.2), respectively. Small changes were noted after adjusting for time-dependent changes in statin and aspirin use. Among women 65 years or older enrolled in Medicare, WHI-adjudicated risks were also lower than predicted, but observed (predicted) risks became aligned after including events ascertained by linkage with CMS for additional surveillance for events: 3.8 (4.3), 7.1 (6.4), 8.3 (8.7), and 18.9 (18.7), respectively. Similar results were seen across ethnic/racial groups. Overall, the equations discriminated risk well (C statistic, 0.726; 95% CI, 0.714-0.738). CONCLUSIONS AND RELEVANCE Without including surveillance for ASCVD events using CMS, observed risks in the WHI were lower than predicted by PCE as noted in several other US cohorts, but risks were better aligned after including CMS events. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT00000611.