Researchers used new statistical methods to analyze public data on the global health burden due to drug addiction. They showed that drug-related mortality has increased 2.2-fold between 1990 and 2021, especially in high-income countries, despite a 6% reduction in cases after correcting for population growth. This surge in the public health burden from drugs was greatest in the US, and likely due to the combination of opioids and cocaine and worsening social and healthcare conditions for drug users.

Drug use disorder (DUDs), also called drug addiction, is the chronic and relapsing use of psychoactive substances in spite of considerable harm to the patient. The UN Office on Drugs and Crime has estimated that more than 250 million people around the world used illegal drugs at least occasionally in 2021, while 39.5 million people suffered from DUD.

But is this considerable global health burden increasing or decreasing? And what are the predicted trends for the near future? Now, a team of researchers from China has applied state-of-the-art statistical methods to find the answer to these questions. They have published their results in Frontiers in Psychiatry.

“We show that, while the number of new and existing cases of DUD changed little overall between 1990 and 2021, the number of drug-related deaths worldwide has more than doubled, and the total health loss has risen,” said Dr Ning Zhang, a professor at Jinshan Hospital of Fudan University in Shanghai, and the study’s corresponding author.

Zhang and colleagues analyzed records from the Global Burden of Disease Study, collected by the Institute for Health Metrics and Evaluation at the University of Washington in Seattle.

Fewer cases, but more death and disability

The results from their analyses showed that worldwide, the global incidence (that is, new cases per year) of DUD increased by 36% between 1990 and 2021, from 10 million to 13.6 million people. Over the same period, the global prevalence (that is, total cases) of DUD increased by 34% to 53.1 million people.

However, the world’s population also rose by 50% between 1990 and 2021. When the authors corrected for this increase, they found a relative reduction by 6% in the global prevalence rate of DUD, from 709.2 cases per 100,000 in 1990 to 663.8 cases per 100,000 people in 2021.

Despite this slight decline in prevalence rate, the global mortality rate due to drug use increased by 31%, from 1.3 deaths per 100,000 people in 1990 to 1.7 deaths per 100,000 people in 2021. The global number of deaths more than doubled over the same period, from 61,774 to 137,278 deaths per year.

Likewise, the global number of disability-adjusted life years (DALYs; a measure of the number of healthy life-years lost, due to death and disability) surged by 75% from 8.9 million years in 1990 to 15.6 million years in 2021.

The authors concluded that paradoxically, a slightly lower incidence of DUD in 2021 resulted in a much greater health burden around the world.

“The surge in deaths is mostly due to systemic gaps in harm reduction and access to treatment. It’s not necessarily new drugs, but the combination of potent substances like opioids and cocaine, along with worsening social and healthcare conditions for existing users, which is responsible,” said Zhang.

Burden greatest in most developed countries

In general, regions and countries with a high socio-economic index had greater incidences and prevalences of DUD and lost more lives and healthy life-years than those with a low socio-economic index. For example, high-income North America showed an 11.2-fold increase in drug-related deaths between 1990 and 2021, to 74,451 deaths in 2021. The highest prevalence of DUD occurred in the US, with 3,821.4 cases per 100,000 persons in 2021. In western Europe, the prevalence increased by 7% to 1,201.2 cases per 100,000 persons over this period.

The authors found no evidence that these grim numbers will improve anytime soon.

“If current patterns continue, deaths will likely remain high – or rise further – in high-income settings unless overdose prevention, treatment coverage, and harm-reduction are rapidly scaled up,” said Zhang.

“Some middle-income regions may keep improving, but places with aging populations or economic stress could see worsening harms without targeted action.”