Statistical haemoglobin thresholds to define anaemia across the lifecycle

Area of Science:

• Hematology
• Public Health
• Clinical Medicine

Background:

• Current anemia thresholds set by the World Health Organization (WHO) are over 50 years old and based on statistical cutoffs.
• Haemoglobin concentration is influenced by various factors including nutrient deficiencies, illness, inflammation, and genetic conditions, necessitating a carefully defined healthy reference population.

Approach:

• Identified data sources with sufficient clinical and laboratory information to establish an apparently healthy reference sample.
• Excluded individuals with any clinical or biochemical evidence of conditions affecting haemoglobin concentration.
• Estimated discrete 5th centiles with 90% confidence intervals using a fixed-effect model across diverse ancestries.

Key Points:

• Established new, sex-specific haemoglobin thresholds for children, adolescents, and adults across different age groups.
• Identified distinct thresholds for non-pregnant females and males in adulthood, and for pregnant women in the first and second trimesters.
• Found no significant influence of non-clinical genetic factors on haemoglobin concentration across Asian, African, and European ancestries.

Conclusions:

• The derived haemoglobin thresholds are robust and provide a foundation for updating WHO guidelines.
• Results support global harmonization of laboratory, clinical, and public health haemoglobin reference values.
• The study offers a refined approach to defining anaemia, crucial for accurate diagnosis and effective public health strategies.