Anemia affects a third of the world's population and accounts for almost 10% of years lived with disability (YLD), according to a review of data from 187 nations.
Despite the ongoing health burden of anemia, the estimated global prevalence declined from 40.2% in 1990 to 32.9% in 2010, the time frame encompassed by the study. In relative terms, anemia's contribution to YLDs decreased from 11.2% in 1990 to 8.8% in 2010, but absolute numbers continued to rise, reaching 68.4 million YLDs by the end of the study period.
Some positive news emerged from the data, which showed a decline in the prevalence of severe anemia in women and girls, Nicholas J. Kassebaum, MD, of the University of Washington in Seattle, and colleagues reported online in Blood.
"Targeted anemia surveillance and intervention should be a greater priority in high-risk populations, especially young children and females," the authors concluded. "Despite causing so much disability, anemia does not receive its requisite attention in many public health spheres. Such inattention may be partly due to anemia being thought of as a byproduct of other disease processes rather than a target for intervention in and of itself."
"We hope our analysis helps health specialists, donors, and policymakers ... by distilling the heterogeneity of anemia into a single entity while retaining enough information about individual conditions to facilitate formulation of strategies to further reduce anemia burden," they added.
Previous studies of anemia epidemiology have been limited geographically and in terms of information obtained about etiology and severity. To address those limitations, Kassebaum and colleagues analyzed publicly available data from 187 countries and estimated the total prevalence of anemia, prevalence of different degrees of anemia severity, and prevalence by sex.
Using information from the Global Burden of Diseases, Injuries, and Risk Factors Study 2010, investigators determined cause-specific attribution of 17 different conditions associated with anemia.
The analysis showed an overall increase in anemia-related YLDs, but anemia prevalence decreased in both sexes and in all levels of severity. Among males (all ages), the prevalence of mild and moderate anemia decreased substantially, whereas prevalence of severe anemia declined the most in females. The large decrease in severe anemia in females resulted in almost a 5% decline in the average severity of anemia, as compared with an increase of 1.5% in males.
"A decrease in the rate of disease was the primary driver of decreased global burden in both sexes and for all severities of anemia," the authors noted.
Geographically, South Asia accounted for the largest share of global anemia YLDs throughout the study period, so the share declined from 39.8% in 1990 to 37.5% in 2010.
Analysis of cause-specific anemia burden showed that iron deficiency was the leading cause in males and females during the entire study period. Five other conditions followed in terms of contribution to overall burden at all times: hookworm, sickle-cell disorders, thalassemias, schistosomiasis, and malaria. The contributions of malaria, schistosomiasis, and chronic kidney disease (CKD) were the only conditions that had increasing burdens of anemia.
North America had the lowest anemia burden attributable to iron deficiency (3%), whereas other regions had dramatically higher rates: Central Asia (64.7%), South Asia (54.8%), and Andean Latin American (62.3%). High-income areas had larger contributions from hemoglobinopathies, CKD, and gastrointestinal hemorrhage.
Globally, the postnatal period had the highest anemia prevalence, followed by children 1 to 4 years. The same age groups had the least favorable changes in epidemiology during the study period. Anemia associated with CKD increased with age in both sexes, topping out among adults 80 and older.
From age 15 through adulthood, females consistently had higher rates of anemia. Females also had the highest disability weights throughout the study period.
The study is perhaps the most comprehensive to date and documents anemia as a persistent global problem, said Andrew Artz, MD, of the University of Chicago.
"One of the key messages from this publication is that anemia, while we recognize as common across different populations and ages, still tends to be overlooked," Artz, who was not involved in the study, told MedPage Today.
Though global in nature, the results are relevant to North America, he added, explaining that anemia in children is less of a problem as compared with developing countries, but affects older individuals more often.
Primary source: Blood
Source reference: Kassebaum NJ, et al "A systematic analysis of global anemia burden from 1990 to 2010" Blood 2013; DOI: 10.1182/blood-2013-06-508325.