Risk of overdose greater with higher dosage of opioid painkillers

Patients on higher doses of opioid painkillers are more likely to accidentally overdose than those prescribed lower doses, a new study finds.

Those who were prescribed more than 100 milligrams of painkillers a day overdosed more than people limited to 1 to 20 milligrams, researchers at the Department of Veterans Affairs in Ann Arbor, Mich., found. The trend stayed true whether the patient had acute pain, chronic pain, a substance abuse problem or cancer. White, middle-age men were statistically more likely to overdose.

But the number of overdoses was relatively small. In the study, published in the Journal of the American Medical Assn. on Wednesday, researchers estimated that about 0.04% of patients actually overdosed, or about 1 in 2,500 people. Their findings were based on an analysis of about 155,000 patients who were prescribed opioid therapy for pain through the Veterans Health Administration in 2004 or 2005.

The findings may seem obvious, but for patients living in constant pain, lowering the daily dose could be unbearable -- and doctors must constantly weigh the risks. The researchers say in their conclusion:

“The risk of opioid overdose should continue to be evaluated relative to the need to reduce pain and suffering and be considered along with other risk factors.”

And that’s the heart of it — how to balance pain control against risk of overdose.

The FDA offers these three steps in its guide to the safe use of pain medicine:

-Keep your doctor informed of any past history of substance abuse.

-Follow directions carefully. Crushing or breaking pills changes the rate the medication is absorbed. The researchers mention that especially in cancer patients, pain can be unpredictable, and taking medicine when the pain hits might lead to overdose.

-Reduce the risk of drug interactions. Don’t mix with alcohol, antihistamines, barbiturates, or benzodiazepines.

Preventing accidental overdoses won’t be resolved soon. Neither will the need to control pain. A good next step, say the authors, would be more frequent follow-up visits—with urine drug tests—and a more detailed history of past substance use.

But don’t necessarily lower the dose.