Almost one-third of Medicare beneficiaries—nearly 12 million Americans—received a prescription for commonly abused opioids in 2015, according to a new report. Spending for these drugs exceeded $4 billion, according to the Associated Press.

The high level of spending raises concerns about the misuse of these drugs, the report noted. The findings come from the Office of Inspector General for the U.S. Department of Health and Human Services.

“Opioid use can be appropriate in some cases,” the report states. “However, misuse of opioids not only has serious financial costs but also human costs, including deaths from overdoses. Moreover, these continuing high rates provide further evidence of this crisis facing our nation.”

Medicare beneficiaries who got an opioid prescription received an average of five such prescriptions or refills. The most common opioids prescribed were OxyContin, Percocet, Vicodin, fentanyl or their generic equivalents, according to study author Miriam Anderson. “In fact, there were about 40 million prescriptions for these drugs last year,” she said. “That’s enough to give one to every Medicare beneficiary in the country.”

A 2014 analysis of Medicare data by USA Today found one in five of the nation’s 43 million senior citizens received Medicare prescriptions for opioid painkillers, many of them for long periods.

The number of patients 65 and older who received Medicare prescriptions for opioids increased more than 30 percent between 2007 and 2012, the newspaper found. An estimated 8.5 million elderly patients received opioid prescriptions in 2012. Use of some of the most commonly abused opioids, including oxycodone and hydrocodone, increased more than 50 percent. The amount of each opioid given to patients increased an average of 15 percent, to about three months worth of medication.