Association Between Urinary Albumin Excretion and Coronary Heart Disease in Black vs White Adults

Study Questions:

Is excess urinary albumin excretion associated with increased risk for coronary heart disease (CHD), and does this relationship differ by race?

Methods:

Data from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study were used for the present analysis. US adults ages 45 years and older, enrolled between 2003 and 2007 and followed through December 31, 2009, comprised the study population. The cohort was stratified by race and urinary albumin-to-creatinine ratio (ACR) into two groups: 1) incident CHD among 23,273 participants free of CHD at baseline; and 2) first recurrent CHD event among 4,934 participants with CHD at baseline. The primary outcomes of interest were incident and recurrent myocardial infarction (MI) and acute CHD death.

Results:

After excluding those with missing data or on hemodialysis at baseline, a total of 28,207 participants were included in the final analysis. Participants who had higher urinary ACR values were more likely to be older, men, less educated, lower income, current smokers, currently taking statins and antihypertensive medications, and to have higher systolic blood pressure, higher waist circumference, lower mean estimated glomerular filtration rate, higher median high-sensitivity C-reactive protein concentrations, and a history of diabetes, hypertension, and dyslipidemia. A total of 616 incident CHD events (421 nonfatal MIs and 195 CHD deaths), and 468 recurrent CHD events (279 nonfatal MIs and 189 CHD deaths) were observed over a mean time of 4.4 years of follow-up. Among those free of CHD at baseline, age- and sex-adjusted incidence rates of CHD per 1,000 person-years of follow-up increased with increasing categories of ACR in black and white participants, with rates being nearly 1.5-fold greater in the highest category of ACR (>300 mg/g) in black participants (20.59; 95% confidence interval [CI], 14.36-29.51) versus white participants (13.60; 95% CI, 7.60-24.25). In proportional hazards models adjusted for traditional cardiovascular risk factors and medications, higher baseline urinary ACR was associated with greater risk of incident CHD among black participants (hazard ratio [HR] comparing ACR >300 vs. <10 mg/g, 3.21 [95% CI, 2.02-5.09]), but not white participants (HR comparing ACR >300 vs. <10 mg/g, 1.49 [95% CI, 0.80-2.76]) (p value for interaction = 0.03). Among those with CHD at baseline, fully adjusted associations of baseline urinary ACR with first recurrent CHD event were similar between black participants (HR comparing ACR >300 vs. <10 mg/g, 2.21 [95% CI, 1.22-4.00]) vs. white participants (HR comparing ACR >300 vs. <10 mg/g, 2.48 [95% CI, 1.61-3.78]) (p value for interaction = 0.53).

Conclusions:

The investigators concluded that higher urinary ACR was associated with greater risk of incident, but not recurrent CHD in black individuals when compared with white individuals.

Perspective:

These data suggest that urinary ACR may assist clinicians in identification of patients at risk for initial heart disease events, in particular black patients. Further research to examine aggressive risk factor modification and its impact on events in these groups would be an informative next step.

Clinical Topics: Atherosclerotic Disease (CAD/PAD)

Keywords: Myocardial Infarction, Coronary Artery Disease, Follow-Up Studies, European Continental Ancestry Group, Risk Factors, Creatinine, Heart Diseases, Renal Dialysis, Incidence, C-Reactive Protein, Biological Markers, Glomerular Filtration Rate, African Continental Ancestry Group, Diabetes Mellitus


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