Use and interpretation of hemoglobin concentrations for assessing anemia status in individuals and populations: results from a WHO technical meeting

Abstract

Anemia is an important public health problem that negatively affects health of individuals and economic potential of populations. An accurate case definition is critical for understanding burden and epidemiology of anemia, for planning public health interventions, and for clinical investigation and treatment of patients. The current threshold hemoglobin concentrations for diagnosis of anemia were proposed in 1968 and based on studies predominantly of Caucasian adult populations in Europe and North America. The World Health Organization is undertaking a project to review global guidelines for anemia. We describe the process of obtaining input from technical experts, researchers, blood bank experts, policy makers, and program implementers to identify key information or knowledge gaps for anemia diagnosis. From this scoping exercise, six priority areas were identified on diverse topics related to the use and interpretation of hemoglobin concentrations to diagnose anemia in individuals and populations. A call for authors was conducted to produce background, review, and research papers across priority topics. This paper summarizes the first technical meeting, which included commissioned papers as well as case studies, describes key data gaps identified, and describes the next steps in the guideline development process to assess available evidence and define knowledge gaps to improve anemia characterization.

Anemia Prevalence and Anthropometric Status of Indigenous Women and Young Children in Rural Botswana: The San People

“…There is a global consensus concerning the adjustment of Hb values for altitude and smoking; however, whether or not an adjustment for ethnicity is warranted remains controversial. Currently, the WHO is in the process of reviewing and updating the guidelines for the use and applicability of Hb cut-offs to define anemia in different populations [ 41 ]. Following adjustments for ethnicity, anemia prevalence declined significantly (women: from 22% to 7%; children: from 63% to 35%).…”

International values for haemoglobin distributions in healthy pregnant women

“…Finally, considering the indisputable need for pregnancy-specific early warning scores that incorporate maternal Hb changes [ 3 , 22 ] our findings could be used to facilitate earlier recognition and treatment of the unwell pregnant woman and thereby reduce both maternal morbidity and mortality rates worldwide.…”

“…In 2015, WHO initiated a project to review the Hb concentration cut-offs used to define anaemia in individuals and populations; review its social, biological, behavioural, environmental, and contextual determinants, and assess the expected impact of public health interventions for preventing and controlling anaemia and Hb concentrations [21] . In 2018, experts, policymakers and programme implementers met to review key information and identify knowledge gaps relating to the diagnosis of anaemia [22] . The paucity of data relating maternal, newborn and child health outcomes to Hb values was also confirmed in a recent review, which stressed that not enough is known about the gestational age-specific Hb thresholds that predict health risk/protection for mother and infant [23] .…”

Extending strong research to high-altitude infants

“…Anaemia, which is very common in the studied sites, was not taken into account and could easily have influenced RR findings, as an anaemic child will breathe faster regardless of altitude. Current WHO guidelines 4 recommend the use of age, sex, and altitude-adjusted haemoglobin thresholds for diagnosing anaemia at the individual and population levels. WHO recently provided an interim report on a 4-year project to review its global guidelines.…”