The misuse of fentanyl, heroin and nonprescribed opioids is increasing, potentially due to the COVID-19 pandemic, according to a new study.

Researchers from the Quest Diagnostics Health Trends study say the rise in drug misuse may be due to the pandemic’s impact on health care access and support for people most at risk for substance use disorder.

The researchers analyzed more than 872,000 nationwide lab results. Their study is believed to be the largest to examine drug positivity rates before and during the first several months of the pandemic, according to a company news release.

The study found among individuals tested, the drug positivity rate rose 35% for nonprescribed fentanyl and 44% for heroin during the pandemic compared to the period before the pandemic. Nonprescribed opioids rose 10%.

“The COVID-19 pandemic has created the perfect storm for a rise in substance use disorders and other forms of prescription and illicit drug misuse. Stress, job losses and depression compounded with isolation and a lack of access to health services can trigger prescription medication overuse, illicit drug use, or relapses,” said co-author Harvey W. Kaufman, M.D., Senior Medical Director, Head of Health Trends Research Program, Quest Diagnostics.