Global antibiotic use has increased

"Calls to rein in antibiotic use after study shows 65% increase worldwide," reports The Guardian on a new global study which aimed to determine trends in antibiotic consumption from 2010-2015 in 76 countries. The study compared consumption between low-middle income countries (LMIC), such as China and India, and high-income countries (HIC) such as the UK and US.

Antibiotics are used to treat bacterial infections but it is well documented that the use of antibiotics has been steadily increasing. Overuse leads to bacteria developing resistance to antibiotics, and resistance is overtaking the speed with which we can create new antibiotics. If this pattern doesn't change we could reach a point where infections become untreatable and even standard surgical procedures become hazardous.

This study found that global antibiotic consumption had increased by 65% over the 15-year period studied. The consumption of antibiotics was greater in LMICs compared with HICs. Of particular concern was the high use of the strongest "last resort" antibiotics which are normally used for the most severe infections.

This study can't demonstrate the causes of increased antibiotic consumption, but growing antibiotic resistance is a global public health threat. And as a global threat it could well be the case that a global response is needed.

Many commentators have argued that antibiotic resistance poses a similar, or even greater, threat to climate change to our long-term future.

Where did the story come from?

The study was carried out by researchers from institutions in the US, Switzerland, Sweden and Belgium, including Johns Hopkins University and the University of Antwerp. Individual authors received funding grants from several organisations, including the Bill and Melinda Gates Foundation and the Global Antibiotic Resistance Partnership.

The study was published in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS). It's available on an open access basis and is free to read online.

Generally the UK media coverage on this story was balanced, if lacking in detail and accuracy in places.

What kind of research was this?

This was an analysis of observational data with the aim of determining trends in antibiotic consumption from 2010-2015 in 76 countries.

Antibiotic resistance – when bacteria are able to adapt and even overcome the effects of antibiotics – is often linked to the increasing consumption of antibiotics. As an imminent global public health threat, many countries have adopted national action plans addressing antibiotic resistance.

The researchers of this study wanted to assess the trends in antibiotic consumption between high-income (HIC) and low-middle income countries (LMIC).

While HICs have been reported to take efforts to limit the use of antibiotics, there is concern that a reverse trend has been occurring in LMICs.

Observational studies like this one are useful for studying trends in health practices such as antibiotic prescribing. However, it isn't possible to infer cause and effect from this type of study and say which factors are influencing the increase in prescribing rates, such as some countries offering antibiotics on an over-the-counter basis.

What did the research involve?

The researchers estimated data on global antibiotic consumption from an ongoing data analysis project that tracks medical sales from more than 90 countries. Researchers were able to use the data to estimate the total sales for each type of antibiotic. Monthly or quarterly antibiotic consumption were reported, by country, for the hospital and prescribing sectors.

Data was obtained for 76 countries from 2010 to 2015. Complete data was available for 66 countries and partial data for the remaining 10. Consumption rates were compared between groups of countries based on their Wold Bank income classification as of 2007.

In addition to this, the researchers looked, by country and year, at the rate of antibiotic consumption according to economic and health indicators such as economic growth and population levels in urban areas.

The researchers also projected global antibiotic use to 2030 using trends in population growth.

Two model scenarios were created:

no policy changes, where the same rate of antibiotic consumption for 2010-2015 was also assumed for 2016-2030
introduction of a target policy where all countries were assumed to converge to the 2015 global average rate for consumption by 2020

What were the basic results?

Between 2000 and 2015, antibiotic consumption increased by 65% from 21.1 billion defined daily doses (DDDs) – eg a single antibiotic capsule or injection – of antibiotics to 34.8 billion DDDs. The antibiotic consumption rate increased by 39% from 11.3 to 15.7 DDDs per 1,000 inhabitants per day.

The primary driver of the increase in global consumption was the increased consumption in low-middle income countries:

In LMICs antibiotic consumption increased 114% (11.4 to 24.5 billion DDDs) and the consumption rate increased 77% (7.6 to 13.5 DDDs per 1,000 inhabitants per day). This was found to correlate with increased economic development.
The LMICs with highest consumption in 2015 were India, China and Pakistan.
In HICs the total antibiotic consumption increased 6.6% (9.7 to 10.3 billion DDDs) and the rate of consumption increased by 4% (26.8 to 25.7 DDDs per 1,000 inhabitants per day). There was no correlation with economic growth.
The HICs with highest consumption in 2015 were the US, France and Italy.
Consumption of newer and "last resort" antibiotics increased across all countries.

Projections for 2030:

assuming no policy changes, antibiotic consumption was projected to increase by 200% to 128 billion DDDs, with a rate of 41 DDDs per 1,000 people per day
if all countries converged on the 2015 average by 2020, the estimate was an increase of 32% to 55.6 billion DDDs

How did the researchers interpret the results?

The researchers concluded: "Using a global database of antibiotic sales, we found that antibiotic consumption rates increased dramatically in LMICs between 2000 and 2015, and in some LMICs have reached levels previously reported only in HICs. Overall consumption has also greatly increased, and the total amount of antibiotics consumed in LMICs, which was similar to HICs in 2000, was nearly 2.5 times that in HICs in 2015."

Conclusion

This large body of observational data from 76 countries demonstrates the increase in antibiotic prescribing over the past 15 years.

It highlights that consumption of antibiotics is greater in lower-middle compared with high-income countries. The analysis also found an association between rising consumption and increases in general economic prosperity.

Although the researchers highlight rising incomes as a driver for this increase, this association can't be confirmed as a cause of the increase. This type of study isn't able to tell us exactly what may be behind the increase and there could be a number of possible explanations. For example, there may be improvements in diagnosis of bacterial infections, particularly in lower income countries. We can't assume that this is necessarily all due to an increase in inappropriate antibiotic prescribing.

However, this study again highlights the challenge and increasing threat of antibiotic resistance and reinforces the fact that this is now a global problem.

You can help tackle antibiotic resistance by recognising that most coughs, colds and stomach bugs are viral infections. They neither need nor respond to antibiotics. If you are prescribed antibiotics it's important to take the course as prescribed, even if you start to get better. Taking a partial dose may allow any bacteria to build resistance against that antibiotic.