Sept. 16 (UPI) -- A change in China's drug manufacturing regulations played a more significant role in reducing opioid-related overdose deaths in the United States in 2018 than any domestic public health initiatives, an analysis published Wednesday in the journal Addiction found.
A decline in overdose deaths in five states -- Florida, Kentucky, Michigan, Ohio and Pennsylvania -- from 2017 to 2018 coincided with a drop in seizures of the opioid carfentanil by law enforcement over the same period, the researchers said.
The reduction in overdose deaths in these states accounted for nearly 100% of the total national decline in 2018, they said.
Carfentanil is 10,000 times more powerful than morphine and has no approved medical use in humans, according to Jalal and his colleagues.
The drug began to appear in law enforcement drug seizures in 2016 and peaked in 2017 before suddenly declining in 2018. The 2017 spike was concentrated in the five states included in the analysis, the researchers said.
In 2017, China added carfentanil to its list of controlled substances, and the U.S. supply eventually dried up, coinciding with 2018's drop in overdose deaths, they said.
"The U.S. has not bent the curve on the drug overdose epidemic," co-author Hawre Jalal said in a statement.
"We are concerned that policymakers may have interpreted the one-year downturn in 2018 as evidence for an especially effective national response or the start of a long-term trend. Unfortunately, that isn't supported by the data," said Jalal, assistant professor of health policy and management at the University of Pittsburgh.
Opioids were the leading cause of drug overdose deaths in the United States in the first half of 2019, according to data released recently by the U.S. Centers for Disease Control and Prevention.
For this study, Jalal and his colleagues crossed drug overdose data from the CDC with U.S. Drug Enforcement Administration information on the types of drugs seized and submitted to state crime labs.
Much of the country has been in the grips of an "epidemic" of illegal opioid use and overdose deaths over the past 40 years, causing more than 1 million deaths, based on agency estimates.
The number of overdose deaths in the United States has doubled roughly every 11 years, according to Jalal and his colleagues.
However, in 2018, the rate declined by 4.1%, the first drop in overdose deaths since 1990, though provisional 2019 data from the CDC shows a 5.6% rebound in overdose deaths since then.
"We all celebrated when the overdose death rate dropped, but it was premature," co-author Dr. Donald Burke, professor of health science and policy at the University of Pittsburgh, said in a statement.
"When policymakers believe a problem is solved, history has shown that funding is reprioritized to other efforts," he said. "The drug overdose epidemic is not solved."