Many disabled Medicare patients are still using prescription opioid painkillers despite the passage of state laws designed to control use of the drugs, HealthDay reports.

A new study finds 45 percent of disabled Medicare beneficiaries were using prescription opioids in 2012, despite the passage of 81 state laws between 2002 and 2012 that were designed to control use of the drugs. Eight percent of disabled Medicare patients got opioids from four or more doctors.

Researchers from the Dartmouth Institute for Health Policy and Clinical Practice analyzed the effects of these state laws on prescription opioid use in a study of 2.2 million disabled Medicare beneficiaries. They found no significant association between state laws and hazardous prescribing patterns, such as very high daily opioid doses and rate of nonfatal overdose.

The findings are published in The New England Journal of Medicine.

“There is no evidence yet that these laws prevent misuse of prescription opioids,” said lead researcher Ellen Meara. “In this vulnerable population of disabled workers, legal remedies to the opioid epidemic are too weak and too slow.”

She said disabled workers are at especially high risk for opioid abuse, because they “have complex medical and social needs, high rates of poverty, and they are more likely to have diagnoses of mental illness like depression compared with other Americans.” None of the state laws address the “underlying pain and disenfranchisement that has led so many Americans to seek relief of pain with opioids,” she said.

“Over a five-year horizon, I am optimistic that legal remedies may help slow the misuse, abuse and overdose deaths related to prescription opioids,” Meara said. “Unfortunately, the epidemic is spreading and changing rapidly, while the legal response is slow and blunt.”