Study author Anupam Jena, an assistant professor at Harvard Medical School and a physician at Massachusetts General Hospital, said some patients he sees taking opioids -- such as morphine -- are likely getting prescriptions for the medication from more than one doctor. This goes against the standard of care, but it occurs nonetheless, he said.
Jena and colleagues looked at a sample of 20 percent of subscribers to Medicare's prescription benefit, or Medicare Part D, from 2010, including 1.8 million beneficiaries who filled at least one opioid prescription that year.
Jena and colleagues found multiple prescribers were common.
"I thought it would be 5 percent to 10 percent," Jena said. "When we ran the numbers and it turned out to be 30 percent, we were shocked."
The researchers also found a strong correlation between the number of prescribers for a patient and the patient's risk of an opioid-related hospitalization.
The study, published in the British Medical Journal, found patients who received their painkillers from more than one doctor were at a significantly greater risk of hospitalization from complications of narcotic use than patients with a single provider managing their opioid prescriptions.
"As physicians, we tell patients not to drive when they take opioids, but we also need to tell them that it can be dangerous to receive these medications from more than one provider," Jena said.