Prevalence and impact of anemia in hospitalized patients

The prevalence of anemia is increasing in the general population similarly to other comorbidities and is associated with high mortality in a variety of settings. Most studies, however, have analyzed older adults or specific comorbidities, and the independent impact of anemia on outcomes in a general population of hospitalized patients has not been clearly defined.

Retrospective analysis of a medical records database of all consecutive patient discharges (aged 18 years or older) admitted to our institution from January 1, 1999 through December 31, 2008.

A total of 179,516 admissions were included. Of these, 18,589 patients were diagnosed as having anemia (10.4%). There were 123,586 patients younger than 65 years. The prevalence of anemia among all of the discharges was characterized by a significant linear increase across the 10-year time frame, from 8.7% (1999) to 12.8% (2008), as was the average number of comorbidities. Over time, anemic patients were characterized by increasing comorbidity. Anemia was significantly associated with mortality (6.5% vs 2.5%; P < 0.001, odds ratio 2.68). This association remained significant after additional adjustment for demographic characteristics and comorbidities. The risk of mortality was significantly higher in patients younger than 65 years than it was in patients older than 65 (odds ratio 3.2 vs 2.1, respectively).

The prevalence of anemia increased during a 10-year time frame, as did the average number of associated comorbid conditions. With adjustment for time, demographic factors, and additional comorbidities, anemia remained independently associated with mortality. This association was stronger in younger patients.