This is a question I get a lot. My typical answer is “yes, but…”
The “but” can lead to a long discussion. I have a bit of a complex relationship with antimicrobial use (AMU) targets.
- Targets can be useful for driving change, to ultimately help us combat antimicrobial resistance (AMR).
- Targets can also be misleading, ineffective, impractical, unrealistically aspirational and disconnected from what we really need to do.
We need targets that lead to action, but more specifically to effective action.
We don’t need targets that are just used for sound bites, to make it look like we’re doing something but that don’t have a real impact. We have too much of that already.
The concept behind AMU targets is simple. We set a threshold for amount of antimicrobials we use that we want to stay under. Targets can be at the national level, species (human, cattle, pigs, etc.), sector (human hospital, veterinary clinic), prescriber (veterinarian, physician, dentist) or another level.
Targets can be useful if they provide encouragement to act and reduce AMU.
- However, they can also be a smokescreen or sound bite with inadequate underpinning to stand a chance of having any effect.
Targets can be good if they improve AMU.
- Combating AMR is not just about reducing AMU. How we use antibiotics, how long we use them and what drugs we use are as, or more, important than the total amount.
Targets can be bad if they compromise animal health and welfare, disrupt animal care, or result in shifts in drug use that reduce the total amount used but worsen how we use antimicrobials.
Most often, the focus is on the mass of antibiotics used (kgs, tonnes). That’s particularly true at national or international levels, such as the 2022 Muscat Manifesto’s call for a 30-50% reduction in AMU in animals (see excerpt below):
Overall mass is usually the easiest number to calculate, and it’s often a big, scary number that gets lots of attention. However, there are a lot of limitations to using this metric for AMU. We can get more information by looking at use in specific populations or animals, for example, people in hospitals, or cattle in feedlots.
My personal opinion is that mass-based metrics for AMU, which are the main focus for AMU targets, largely suck. I use them, but that’s because it’s typically all we have, but I know they have major limitations. Here’s why:
- Mass just tells us how much weight of antimicrobials went into the overall population (be it animals or people). It doesn’t tell us why, when, how, or what type. Overall mass data (all antimicrobials combined) is particularly useless since we use different doses for different antimicrobials, treat different species differently and there are major differences in sizes of different animals, from grams (chicks) to hundreds of kilograms (cattle).
- Differences in drug potency are also a big problem. For example, if I change from a drug that is dosed at 20 mg/kg twice a day to one that is used as 2 mg/kg once a day, I’ve dropped overall antimicrobial mass used by about 95% (40 mg/kg/day to 2 mg/kg/day). That’s an impressive reduction and it sounds great. However, it could also be the last thing we want, since higher potency (lower dosed) drugs are usually newer, broad spectrum, higher tier drugs that are very important in human medicine. So, if you said we have to reduce antimicrobial use in livestock in Canada by 50%, we could do that quickly by switching to higher potency drugs, but risk making AMR issues much worse (which is the complete opposite of our goal).
- Overall mass data can be useful if we’re comparing apples to apples, such as looking at total kgs of antimicrobials used in beef cattle when the cattle population hasn’t changed and when relative use of different drugs hasn’t changed. That approach has been used successfully to reduce antimicrobial use in livestock in Denmark, through their Yellow Card system. So, I don’t discount the use of refined mass-based approaches, but we can do better, as overall mass used can be misleading in different situations and doesn’t guide optimal antimicrobial stewardship (AMS) activities. Ultimately, it’s a very crude measure that can be hard to use outside of situations where there’s a very narrow and well defined scope of use.
Ok, so I’ve whined enough about how mass-based metrics suck (or at least aren’t good enough). What can we do instead?
I’m pragmatic enough to know that we’re likely going to focus on pretty crude, high level metrics for international declarations, like a 30% reduction in tonnage of AMU in animals. That can be okay if we use more actionable and relevant metrics to underpin that high level goal.
I think we need to move more to appropriate use metrics for AMU targets. From an animal AMU standpoint, we could target things like:
- no use of medically important antimicrobials for growth promotion in any country by 2030
- no use of highest-priority critically important antimicrobials (HPCIAs) for group prophylaxis in animals
- 100% of AMU is done under the guidance of a veterinary professional
- species and life-stage specific targets (e.g. prophylaxis of less than 40% of groups of post-weaning piglets, prophylactic treatment of less than 20% or dry cows)
- percentage of AMU that is consistent with national or international AMU guidelines
We also need to think about targets that don’t directly relate to AMU but which drive AMU indirectly, such as targets that involve access to antimicrobials, healthcare and preventive medicine:
- access to at least one first line antimicrobial for common diseases in all countries
- access of all animal producers to a veterinarian or trained allied animal health professional
- free availability of guidelines that are relevant for the species, region and language of veterinarians and other prescribers
- access to preventive health tools such as vaccination
Can we reach these targets today (or in the very near future)?
- We can achieve some of them, in some countries.
Using effective AMU targets isn’t an immediate fix for improving AMU and reducing AMR. We need to be aware of the many other things that also need to be done:
- We need to be able to accurately measure AMU at an adequately granular level to be able to understand AMU in any given population
- We need to facilitate access to resources and guidelines to improve AMU decision making
- We need to provide support (logistical, expertise, financial) to food animal producers, particularly in developing regions, to improve animal management and preventive medicine as food animal production ramps up
- We need to work with animal owners/producers to overcome barriers to stewardship, which are often psychological (e.g. resistance to change, fear of change)
- We need to streamline access to preventive health tools such as vaccines, as well as access to quality antimicrobials everywhere.
- We need adequate private and public funding to implement the measures needed to reduce the need for AMU and to better monitor AMU
Additionally, we need to monitor to see what works, including impacts on both AMU and AMR. “Doing something” shouldn’t be the end goal. “Doing something that works” should be the target.