The COVID-19 pandemic may be driving a surge in drug-overdose deaths in the U.S., a new study suggests.

In an analysis of emergency medical services data, researchers found that between March and August of 2020, the number of overdose-related cardiac arrests peaked at more than double the average in the prior two years, and remained 48.5 percent higher by the end of the study period, according to the results published in JAMA Psychiatry.

The researchers turned to EMS data because of other sources’ long lag time in reporting data, said the study’s lead author, Joseph Friedman, an MD/PhD student at the University of California, Los Angeles.

The EMS data, which is essentially reported in real time, provided a window on how the social isolation implemented to slow the pandemic might have affected drug overdose deaths.

“Basically, overdose-related cardiac arrest is a proxy for what is happening with overdose mortality,” Friedman said. “And we find a large-scale increase that corresponds pretty closely to decreases in mobility as measured with cell phone data. It appears that as people became more socially isolated, there was a large increase in overdose-related cardiac arrests that peaked at 125 percent above baseline in early May.”

To explore the possible impact the pandemic might have had on overdose-related cardiac arrests, Friedman and his colleagues turned to the National EMS Information System (NEMSIS), a registry of more than 10,000 EMS agencies in 47 states that represent more than 80 percent of EMS activations nationally in 2020.

Friedman and his colleagues calculated weekly overdose-related cardiac arrests, which are determined onsite, and overdose-related EMS activations, which are determined by dispatch. Then compared 2020 trends to a baseline of weekly averages in 2018 and 2019.

The 2020 NEMSIS database included 25.9 million EMS activations. During April of 2020, overdose-related cardiac arrests rose sharply, and by May 4, they had reached 74.1 per 100,000 EMS activations (123.4 percent above baseline). Overdose-related cardiac arrests subsequently decreased but remained elevated, reaching 48.7 per 100,000 EMS activations (53.7 percent above baseline) by July 27.

Through August 1, overdose-related cardiac arrests in 2020 totaled 49.5 per 100,000 EMS activations, or 48.5 percent above baseline. These trends corresponded temporally with a sharp drop in people’s mobility, which began on March 16 and by April 13 reached a minimum of −51.8 percent of what had been observed in the prior two years. Mobility slowly increased to −24.3 percent by July 27.