Faculty Bibliography

BACKGROUND: National data show unexplained racial disparity in albuminuria. We assessed whether low serum vitamin D status contributes to racial disparity in albuminuria. METHODS: We examined the association between race and albuminuria (spot urinary albumin/creatinine ratio (ACR) >/=30) among non-Hispanic black and white nonpregnant adults who were free of renal impairment in the National Health and Nutrition Examination Survey (NHANES) from 2001-2006. We conducted analyses without and with serum 25(OH)D. We adjusted for age, sex, education level, smoking, body mass index (BMI), diabetes, diagnosis of hypertension, and use of antihypertensive medication. RESULTS: Albuminuria was present in 10.0% of non-Hispanic blacks and 6.6% in non-Hispanic whites. Being black (odds ratio (OR) 1.46; 95% confidence interval (CI) 1.23-1.73) was independently associated with albuminuria. There was a graded, inverse association between 25(OH)D level and albuminuria. Notably, the association between race and albuminuria was no longer significant (OR 1.19; 95% CI 0.97-1.47) after accounting for participants' serum 25(OH)D. Similar results were observed when participants with macroalbuminuria (ACR >/=300 mg/g) or elevated parathyroid hormone (>74 pg/ml) were excluded or when a continuous measure of 25(OH)D was substituted for the categorical measure. There were no interactions between race and vitamin D status though racial disparity in albuminuria was observed among participants with the highest 25(OH)D levels . CONCLUSION: Suboptimal vitamin D status may contribute to racial disparity in albuminuria. Randomized controlled trials are needed to determine whether supplementation with vitamin analogues reduces risk for albuminuria or reduce racial disparity in this outcome.

BACKGROUND: Blunted nocturnal blood pressure (NBP) dipping is a significant predictor of cardiovascular events. Lower socioeconomic position (SEP) may be an important predictor of NBP dipping, especially in African Americans (AA). However, the determinants of NBP dipping are not fully understood. METHODS: The cross-sectional associations of individual and neighborhood SEP with NBP dipping, assessed by 24-h ambulatory BP monitoring, were examined among 837 AA adults (Mean age: 59.2 +/- 10.7 years; 69.2% women), after adjustment for age, sex, hypertension status, body mass index (BMI), health behaviors, office, and 24-h systolic BP (SBP). RESULTS: The mean hourly SBP was consistently lower among participants in the highest category of individual income compared to those in the lowest category, and these differences were most pronounced during sleeping hours. The odds of NBP dipping (defined as >10% decline in the mean asleep SBP compared to the mean awake SBP) increased by 31% (95% confidence interval: 13-53%) and 18% (95% confidence interval: 0-39%) for each s.d. increase in income and years of education, respectively, after multivariable adjustment. CONCLUSIONS: NBP dipping is patterned by income and education in AA adults even after accounting for known risk factors. These results suggest that low SEP is a risk factor for insufficient NBP dipping in AA.