Although many doctors aren’t in favor, more states are moving to force doctors to check on patients’ prescription history before prescribing opioid painkillers.

While studies show prescription drug monitoring programs (PDMPs) work (a 2016 study found they prevent about one opioid death every two hours), and a survey of doctors found 43 percent believe a broader use of interoperable PDMPs across state lines is the most effective option to solve the country’s opioid epidemic, many doctors have fought mandatory PDMPs, along with the two largest physician associations, the American Medical Association (AMA) and the American College of Physicians, according to The Washington Post.

But doctors are wary of more regulations that mandate how they manage their patients and practices.

In the past four years, 18 states have made it mandatory for doctors who prescribe opioids and other controlled substances to check PDMP databases, according to the Post. About 13 other states have weaker rules that cover more limited circumstances under which physicians are mandated to check PDMPs before writing opioid prescriptions.

But 22 states with PDMPs don’t require prescribers check them, according a Pew Charitable Trusts report, despite the fact mandating their use is the single most effective way to increase use of the electronic databases.

The result of the state-by-state approach is a patchwork of rules that allow opioid abusers to “doctor shop,” crossing state lines to obtain prescription opioids. For example, in Massachusetts opioid addicts can drive an hour to three or four different states and get drugs from doctors not linked to the state’s PDMP.

So why are doctors opposed?

“When you pass a mandate, you create other consequences that you sometimes don’t want,” Steven Stack, M.D., immediate past president of the AMA and an emergency-room physician in Lexington, Kentucky, told the newspaper. Mandated use imposes yet another time-consuming task on busy doctors and staff in hospital emergency rooms when patients require narcotics to treat pain, he said.

Primary care physician Daniel Alford, M.D., director of the Clinical Addiction Research and Education unit at the Boston University School of Medicine, said he must check each patient under Massachusetts’ mandated PDMP, but told the Post it's rare he finds doctor-shopping.

Further, he doubts it's the best use of a doc's time. Most states, he notes, allow delegates such as nurses to check the database.