Anemia: An Independent Predictor of Death and Hospitalizations among Elderly Patients With Atrial Fibrillation

The prevalence of atrial fibrillation (AF) among people older than 75 y is 12%, with a similar prevalence for anemia in people aged 75-84 y; anemia occurs in 25% of people older than 85 y. Although anemia is implicated as a prognostic marker and carries an increased mortality among patients with heart disease and HIV infection, no study has investigated specifically the association between AF, anemia, and outcomes. This retrospective cohort study by Sharma and coworkers examined and quantified the relationship between anemia and mortality and hospitalizations in 13,067 elderly patients with AF. Patients were selected from among Medicare beneficiaries hospitalized with AF and included in the National Registry of Atrial Fibrillation II data set. The index hospitalization hematocrit (Hct) was obtained within 24 h of admission and classified into one of the following categories: <25%, 25-29.9%, 30-34.9%, 35-39.9%, 40-44.9%, 45-49.9%, and ≥50%. Variables examined included age, sex, discharge medications, and prevalent comorbid conditions including blood transfusions. The primary outcome was all-cause mortality during a mean follow-up of 12 mo. The mean age of the patients was 79.8 y and the mean Hct value was 39.2%, with Hct decreasing progressively with older age; diabetes, heart, prior myocardial infarction, and stroke/transient ischemic attacks were present in 25%, 57%, 37%, and 29%, respectively. During the follow-up, 3665 deaths occurred. The most favorable survival rate was found in the patients with an Hct of 40-49.9%. Patients with an Hct <25% had the worst survival, with an increasing risk of death with decreasing Hct for those with Hct <45%. Using the Hct of 40-44.9%, the adjusted hazard ratios for mortality were 1.66, 1.50, 1.28, 1.07, 1.03 and 1.10 for Hct values of <25%, 25-29.9%, 30-34.9%, 35-39.9%, 45-49.9%, and ≥50%, respectively. The overall effect of anemia was significant in the entire cohort; women with an Hct of 40-44.9% and men with Hct of 45-49.9% had the most favorable survival. Those with an Hct <25% had double the risk of death among men compared with a value of 45-49.9%, with an adjusted hazard ratio of 2.23; this effect was less marked in women (adjusted hazard ratio 1.41). For women within the same Hct category, the adjusted hazard ratio was 1.41. Anemia was a stronger predictor of death in patients with coronary artery disease than in patients without the disease. No significant interaction of Hct was found with heart failure or diabetes. During follow-up, 8364 rehospitalizations were reported, with a 1.28-fold increased risk for patients in the 25-29.9% category compared with the 40-44.9% category. These results provide clinical implications for assessing prognosis and optimizing therapy in elderly patients with AF. Whether anemia is a mediator of adverse outcomes or a marker for those with a worsened prognosis related to concomitant illness requires additional study, preferably randomized clinical trials to determine if interventions to correct anemia are effective and safe in patients with AF.