Importance: Excess urinary albumin excretion is more common in black than white individuals and is more strongly associated with incident stroke risk in black vs white individuals. Whether similar associations extend to coronary heart disease (CHD) is unclear.
Objective: To determine whether the association of urinary albumin excretion with CHD events differs by race.
Design, setting, and participants: Prospective cohort study of black and white US adults aged 45 years and older who were enrolled within the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study between 2003 and 2007 with follow-up through December 31, 2009. We examined race-stratified associations of urinary albumin-to-creatinine ratio (ACR) in 2 groups: (1) incident CHD among 23,273 participants free of CHD at baseline; and (2) first recurrent CHD event among 4934 participants with CHD at baseline.
Main outcomes and measures: Expert-adjudicated incident and recurrent myocardial infarction and acute CHD death.
Results: 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 1000 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% CI, 14.36-29.51) vs 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 = .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 = .53).
Conclusions and relevance: Higher urinary ACR was associated with greater risk of incident but not recurrent CHD in black individuals when compared with white individuals. These data confirm that black individuals appear more susceptible to vascular injury.