An observational study at an outpatient clinic in the United Kingdom found that patients with chronic heart failure who had anemia had higher rates of all-cause and cardiovascular mortality compared with those who did not have anemia. More than one-quarter of the patients had anemia.

Lead researcher John G. F. Cleland, MD, of Castle Hill Hospital in the United Kingdom, and colleagues published their results online in JAMA Cardiology on June 29.

“This was a single-center study serving a predominantly white population but including a population of mixed ethnicity,” the researchers wrote. “Data should be extrapolated with care to centers that serve populations different from ours or if different criteria are used to define [heart failure]. However, we enrolled consecutive patients, which may make this study more epidemiologically representative than many multicenter studies that enroll patients in a selective and nonconsecutive fashion.”

The study included 4,456 patients who were referred for suspected heart failure to a cardiology outpatient clinic from Jan. 1, 2001, through Dec. 31, 2010. The researchers estimated that fewer than two percent of patients refused to participate or were excluded.

They used the World Health Organization criteria for defining anemia, which is a hemoglobin concentration of less than 12.0 g/dL in women and less than 13.0 g/dL in men.

The median age of patients was 73 years old, while 39.5 percent were women and 40.2 percent had left ventricular systolic dysfunction (LVSD).

In addition, 27.8 percent of the patients had anemia, including 14.4 percent with mild anemia, 7.9 percent with moderate anemia and 5.4 percent with marked anemia. Patients with LVSD had a higher prevalence of anemia, while patients with anemia were more likely to have a low serum concentration level.

Of the patients without LVSD, 26.3 percent had a plasma N-terminal pro-brain natriuretic pedtide concentration of greater than 400 pg/mL, 18.9 percent had a level of less than 400 pg/mL and 14.6 percent had no measurement.

Further, 43.2 percent to 68.0 percent of patients with anemia had iron deficiency, while 14.7 percent to 35.3 percent of patients without anemia had iron deficiency.

Multivariable analyses found that lower hemoglobin and serum iron concentrations were associated with higher all-cause and cardiovascular mortality.

“The prevalence of anemia is similar regardless of the underlying [heart failure] phenotype and, even if borderline, is often associated with iron deficiency,” the researchers wrote. “However, the prevalence of anemia and iron deficiency is highly dependent on how these terms are defined; by some definitions, most patients will have at least one or the other. Bone marrow histologic analysis reveals a high prevalence of iron depletion in patients with [heart failure], reinforcing the belief that iron deficiency makes an important contribution to the development of anemia in this setting.”