Anemia is an independent risk factor for cardiovascular and renal events in hypertensive outpatients with well-controlled blood pressure: a subgroup analysis of the ATTEMPT-CVD randomized trial.

To investigate whether anemia is an independent risk factor for cardiovascular and renal events in hypertensive outpatients, we performed a subgroup analysis of the ATTEMPT-CVD study based on baseline hemoglobin. The ATTEMPT-CVD study was a multicenter, prospective, randomized study of hypertensive outpatients that compared the efficacy of angiotensin receptor blocker (ARB)-based antihypertensive treatment with non-ARB antihypertensive treatment over 3 years. In the present subanalysis, ATTEMPT-CVD study participants (n = 1213) were categorized into the anemic group and nonanemic group according to their baseline hemoglobin. We compared the anemic and nonanemic groups mainly in regard to the incidence of cardiovascular and renal events and blood pressure. We also performed a multivariable Cox proportional hazards analysis to determine the prognostic factors that were independently associated with cardiovascular and renal events. Of the 1213 patients enrolled in the ATTEMPT-CVD, 194 patients had anemia (mostly mild anemia) and 1019 patients did not. Blood pressure was well-controlled during the 3 years of antihypertensive therapy in both the anemic and nonanemic groups. However, the incidence of cardiovascular and renal events was significantly greater in the anemic group than in the nonanemic group (HR = 1.945: 95%CI 1.208-3.130; P = 0.0062). Even after adjustment, anemia was independently associated with cardiovascular and renal events (HR = 1.816: 95%CI 1.116-2.955; P = 0.0163) in overall hypertensive patients with well-controlled blood pressure. Anemia, even mild anemia, is an independent risk factor for cardiovascular and renal events in hypertensive outpatients whose blood pressure is well-controlled. Thus, anemia may be a novel therapeutic target for cardiovascular and renal diseases in hypertensive outpatients with anemia.