The Prevalence of Anemia and Moderate-Severe Anemia in the US Population (NHANES 2003-2012)

Abstract

Since anemia is associated with poor health outcomes, the prevalence of anemia is a significant public health indicator. Even though anemia is primarily caused by iron deficiency, low oxygen-carrying capacity may result from other conditions such as chronic diseases, which remain a relevant health concern in the United States. However, studies examining current rates of anemia in the total US population and in more specific subgroups are limited. Data from five National Health and Nutrition Examination Surveys (NHANES) from 2003 to 2012 were analyzed to assess two outcomes: anemia and moderate-severe anemia, which were based upon serum hemoglobin levels (Hb) as per World Health Organization (WHO) definitions. Statistical analysis using SAS examined temporal trends and the prevalence of anemia among sexes, age groups, and races/ethnicities. The study estimated that an average of 5.6% of the U.S. population met the criteria for anemia and 1.5% for moderate-severe anemia during this 10-year period. High-risk groups such as pregnant women, elderly persons, women of reproductive age, non-Hispanic blacks, and Hispanics were identified, and relationships between multiple risk factors were examined. Rates of anemia in men increased monotonically with age, while that of women increased bimodally with peaks in age group 40-49 years and 80-85 years. The effect of risk factors was observed to compound. For instance, the prevalence of anemia in black women aged 80-85 years was 35.6%, 6.4 times higher than the population average. Moreover, anemia is a growing problem because of the increased prevalence of anemia (4.0% to 7.1%) and moderate-severe anemia (1.0% to 1.9%), which nearly doubled from 2003-2004 to 2011-2012. Thus, these results augment the current knowledge on anemia prevalence, severity, and distribution among subgroups in the US and raised anemia as an issue that requires urgent public health intervention.

Fig 1. Prevalence of anemia and moderate-severe anemia by gender, age group, and race/ethnicity, NHANES 2003–2012.

*The weighted prevalence percentages reflect the prevalence of total anemia and moderate-severe anemia, survey weighted to the US population. The analysis was limited to subjects without pregnancy as defined in the Methods section (N = 41,026): Non-Hispanic White (N = 16,157), Non-Hispanic Black (N = 9,826) and Hispanic (N = 12,156).

Fig 2. Percentage distribution of serum hemoglobin (g/dL) by gender, NHANES 2003–2012.

* Female mean Hb: 13.4 g/dL, 95% CI: 13.4–13.5 g/dL; Male mean Hb: 14.9 g/dL, 95% CI: 14.9–15.0 g/dL. ^†The weighted percentages reflect the distribution of Hb, survey weighted to the US population. The graph is independent of age, race and ethnicity. The analysis was limited to subjects without pregnancy as defined in the Methods section (N = 41,026), Males (N = 20,719) and Females (N = 20,307).