Research published in the British Journal of Haematology shows that dose reductions in immunoglobulin replacement are associated with increased antibiotic usage in patients with antibody deficiency. This article written by Dr Adrian Shields at the University of Birmingham explains the findings.

Determining the correct immunoglobulin dose for individuals with primary and secondary immunodeficiency is as much of an art, as it is a science. Many research studies have sought to understand immunoglobulin dosing for individuals with immunodeficiencies and found that different people require different levels of antibody to remain infection free. There are complex reasons for this including the nature of an individual’s immunodeficiency and their exposure to germs that might cause infection. This has led to the consensus that immunoglobulin doses should be personalised to the individual, rather than using a one-size-fits-all approach.

Unfortunately, the COVID-19 pandemic had a significant impact on immunoglobulin supply to the NHS. Global plasma donations fell and a 14% reduction in supply was observed by mid-2021. Accordingly, the remaining supply of immunoglobulin had to be managed to ensure those most in need were prioritised. In the West Midlands region, a decision was made to consider reducing the dose of immunoglobulin in individuals who were clinically stable (i.e. essentially infection free), if their antibody levels were greater than 8g/L. This level is well within the normal range of antibody levels in the blood of healthy people.

This new research led by Dr Adrian Shields examined the consequences of this approach. Dr Shields’ team identified 61 individuals with immunodeficiencies who had their immunoglobulin dose reduced and compared them to another group of 36 individuals who dose remained unchanged. Both groups were clinically stable, but those who had their immunoglobulin dose reduced had, on average, higher “trough” antibody level prior to dose reduction.

The team then compared how often infections requiring courses of antibiotics occurred in each group during the 12 months before and after immunoglobulin dose reductions. In the 12 months before, there was no difference in the frequency of infections needing additional antibiotics between the groups. However, after dose reductions, infections requiring antibiotics in the dose-reduced group significantly increased. On average, individuals required antibiotics 1.55 times more often than those whose immunoglobulin dose was left unchanged. Overall, the proportion of individuals who remained completely infection-free in the dose reduced group fell from 61% in the year before dose-reduction to 28% in the year after. Many individuals have since had their original immunoglobulin doses restored.

The research team concluded that their study supports the existing consensus of tailoring immunoglobulin dosing to each individual with immunodeficiency. They also call for more research to understand the relationship between immunoglobulin dosing, infections, and antibiotic use amongst patients with immunodeficiency.

The research was published in June 2023 in the British Journal of Haematology: Dose reductions in immunoglobulin replacement are associated with increased antibiotic usage in patients with antibody deficiency. Br J Haematol. 2023 Jun 20. doi: 10.1111/bjh.18910.