GOLD provides pragmatic guidance, such as acknowledging the potential role of blood eosinophils to inform inhaled corticosteroid (ICS) prescribing. Emerging research has looked at how blood eosinophil levels of people living with COPD may predict the magnitude of response to inhaled corticosteroid therapy.

It is important to note that the potentially raised levels cited in papers are within the normal range – albeit at the upper end of normal – and there is still no consensus on what threshold to use or national recommendation of how to apply these findings to improve patient care.

The GOLD 2020 report suggests that people with blood eosinophil counts of less than 0.1/litre are unlikely to respond to ICS treatment, and those with a blood eosinophil count greater than 0.3/litre are more likely to respond. However, these levels should not be regarded as absolute cut-off values. For example, a higher eosinophil count (i.e. above the normal range) is often, but not always, observed in people living with asthma. People with confirmed asthma can have inflammation that is not associated with a raised eosinophil level, but still derive benefit from ICS.

Blood eosinophils can be used to guide healthcare professionals as to who is more likely to derive benefit from ICS, but people should be treated on an individual basis.