Racial impact of diurnal variations in blood pressure on cardiovascular events in chronic kidney disease

Ambulatory blood pressure parameters, nocturnal dipping and morning surge, are associated with cardiovascular outcomes in several populations. While significant variation exists between racial groups in ambulatory blood pressure measurements and the incidence of cardiovascular disease, the effect of race on the associations of dipping and morning surge with cardiovascular outcomes is unknown. In a prospective analysis of 197 African American and 197 Japanese individuals with non-diabetic chronic kidney disease matched by age and renal function, we analyzed the associations of dipping and morning surge with cardiovascular events for both races and assessed whether these relations differed by race. Higher sleep-trough morning surge was independently associated with cardiovascular events in Japanese (hazard ratio, 1.93 per 10 mm Hg; 95% confidence interval, 1.20-3.10) but not in African American participants, with race an effect modifier (P-value <.01). Dipping was not associated with cardiovascular events in either racial group. In individuals with chronic kidney disease, the association between morning surge and cardiovascular events appears to be dependent upon race, with higher morning surge a risk factors in Japanese but not in African Americans.