Spending by health insurance companies increased more than 1,300 percent over four years for patients with an opioid abuse or dependence diagnosis, NPR reports.

Spending on insurers’ payments to hospitals, labs, treatment centers and other medical providers for these patients rose from $32 million to $446 million between 2011 and 2015. Insurers spent an average of $3,435 on patients annually, but for those with a diagnosis of opioid dependence or abuse, they spent $19,333. Much of that spending was due to emergency room visits and lab tests.

The findings come from Fair Health, a nonprofit databank that provides health industry cost information.