Nearly 70,000 people on Medicare's drug plan received “extreme” amounts of narcotic painkillers in 2016 and more than 22,000 others appeared to be “doctor shopping” for drugs, patterns that put both groups “at serious risk of opioid misuse or overdose,” a government watchdog reported Thursday.

In all, about half a million people on the drug plan took amounts of the powerful drugs considered too large under standards set by the Centers for Disease Control and Prevention, according to the Inspector General's office of the U.S. Health and Human Services Department. That number excludes people who had cancer or were in hospice, who may require large doses of painkillers.

The report highlights another aspect of the prescription opioid epidemic that killed more than 15,000 people via overdoses in 2015: potential abuse by older and disabled people who qualify for Medicare Part D, the program's optional prescription drug benefit. In 2016, 43.6 million people were covered. Medicare primarily serves people who are older than 65.

The opioid crisis has been most closely linked to people between the ages of 25 and 44, particularly economically stressed whites and people in rural and small-town America. But the new report shows that older people are far from immune.

As pressure to rein in use of addictive painkillers has grown along with the epidemic, some older people and patients in chronic pain have pushed back, worrying that they will not be able to obtain the medications they say allow them to function.

In a Washington Post poll published in December, a majority of long-term opioid users said the drugs have dramatically improved their lives by relieving intractable pain, and two-thirds said the relief is well worth the risk of addiction.

The nearly 70,000 extreme users received the equivalent of 240 milligrams of morphine every day for the entire year, Inspector General Daniel R. Levinson's office reported. The CDC recommends avoiding consumption of more than 90 milligrams per day and says use of the drugs for more than three months substantially raises the risk of dependence. The most common drugs were Tramadol and pills containing hydrocodone or oxycodone.

In the extreme group, 678 people received more than 1,000 milligrams a day for the entire year — a level that might indicate they were selling or otherwise diverting their drugs to others. One person in New Hampshire was prescribed 13 months worth of 80-milligram OxyContin, 13 months of 60-milligram OxyContin, 13 months of 40-milligram OxyContin, 14 months of 30-milligram oxycodone and 13 months of fentanyl patches.

The 22,308 doctor shoppers received more than 120 milligrams of controlled substances daily for at least three months, and used at least four prescribers and four pharmacies in 2016.

“Although beneficiaries may receive opioids from multiple prescribers or pharmacies for legitimate reasons,” the report noted, “these patterns raise concern.”

The report found sharp differences among states in opioid consumption. In Alabama, 46 percent of Part D beneficiaries had received at least one opioid, and in Mississippi, the figure was 45 percent. At the low end of the scale was Hawaii (21 percent) and New York (22 percent). Overall, 1 in 3 Medicare drug beneficiaries received an opioid last year.

Those drugs were authorized by more than 115,000 prescribers who ordered opioids for at least one person at serious risk of misuse or overdose because of their consumption patterns or doctor shopping, the inspector general concluded. The vast majority did so for just one or two patients, but 198 of them each prescribed drugs for at least 44 beneficiaries receiving extreme amounts of the addictive painkillers.

One Florida physician ordered the equivalent of 1,239 milligrams daily of oxycodone and fentanyl for a single patient. The doctor's overall prescribing habits cost Medicare Part D $1.6 million.

A third of the 401 prescribers who showed “questionable prescribing patterns” were nurse practitioners or physician assistants.

Every state but Missouri has established databases that prescribers are required or encouraged to check for signs of doctor shopping or abuse before authorizing the drugs. Some authorities believe that these “prescription drug monitoring programs” are helping to curb doctor shopping for painkillers.

Also on Thursday, the National Academies of Science, Engineering and Medicine predicted that it would take years to undo the harms of the prescription and illegal opioid crises. In a new report on pain management and the opioid epidemic, a panel of experts urged the Food and Drug Administration to begin considering the public health implications of new opioid medications and conduct a full review of the safety and effectiveness of all opioids currently on the market.

The organization, which provides independent guidance on a wide variety of policy issues, also called for the expansion of treatment for substance abusers and improved insurance coverage for comprehensive pain management using both drugs and non-pharmacological techniques. The panel also recommended explicit authorization of needle exchange programs, along with sale or distribution of syringes.