From Bad to Worse: Anemia on Admission and Hospital-Acquired Anemia

Anemia at hospitalization is often treated as an accompaniment to an underlying illness, without active investigation, despite its association with morbidity. Development of hospital-acquired anemia (HAA) has also been associated with increased risk for poor outcomes. Together, they may further heighten morbidity risk from bad to worse.

The aims of this study were to (1) examine mortality, length of stay, and total charges in patients with present-on-admission (POA) anemia and (2) determine whether these are exacerbated by development of HAA.

In this cohort investigation, from January 1, 2009, to August 31, 2011, a total of 44,483 patients with POA anemia were admitted to a single health system compared with a reference group of 48,640 without POA anemia or HAA.

Data sources included the University HealthSystem Consortium database and electronic medical records. Risk-adjustment methods included logistic and linear regression models for mortality, length of stay, and total charges. Present-on-admission anemia was defined by administrative coding. Hospital-acquired anemia was determined by changes in hemoglobin values from the electronic medical record.

Approximately one-half of the patients experienced worsening of anemia with development of HAA. Risk for death and resource use increased with increasing severity of HAA. Those who developed severe HAA had 2-fold greater odds for death; that is, mild POA anemia with development of severe HAA resulted in greater mortality (odds ratio, 2.57; 95% confidence interval, 2.08-3.18; P < 0.001), increased length of stay (2.23; 2.16-2.31; P < 0.001), and higher charges (2.09; 2.03-2.15; P < 0.001).

Present-on-admission anemia is associated with increased mortality and resource use. This risk is further increased from bad to worse when patients develop HAA. Efforts to address POA anemia and HAA deserve attention.