Gender differences in the association between discharge hemoglobin and 12-month mortality after acute myocardial infarction

BACKGROUND:Anemia at discharge in patients with acute myocardial infarction is associated with poor prognosis; whether this differs in women and men or if there is a threshold value at which these relationships change is unknown. HYPOTHESIS:Women have a lower discharge hemoglobin (Hb) at which outcomes worsen. METHODS:We identified patients with acute myocardial infarction in the TRIUMPH registry between 2005 and 2008. In multivariable models, we evaluated the relationship between discharge Hb and 12-month mortality and tested whether this relationship varied by gender. We assessed whether the relationship with discharge Hb values was nonlinear using a restricted cubic spline term. RESULTS:Of 4243 patients with AMI, 32.9% were female. Mean admission Hb was 12.9 ± 1.9 g/dL in women and 14.5 ± 2.0 g/dL in men, with mean discharge Hb 11.4 ± 1.8 g/dL and 12.9 ± 1.9 g/dL, respectively. Lower discharge Hb was independently associated with increased mortality (P < 0.05). In multivariable models, discharge Hb decline was similarly associated with increased 12-month mortality in women and men (per 1-g/dL decrease Hb; women HR: 1.24, 95% CI: 1.09-1.42, P < 0.01; and men HR: 1.25, 95% CI: 1.13-1.37, P < 0.01; P for gender interaction = 0.99). The relationship between discharge Hb and 12-month mortality was linear (P for nonlinear spline term = 0.12). CONCLUSIONS:Lower discharge Hb levels were similarly associated with increased 12-month mortality in women and men. These relationships are linear without a clear threshold, suggesting any decline in discharge Hb is associated with poor outcomes.