A new study found that about two-thirds of emergency visits for drug overdoses involve prescription painkillers.

Researchers from Stanford University School of Medicine looked at a sample from the 2010 nationwide data of drug overdoses and emergency room visits.

Their findings showed that 68 percent of the overdoses were related to prescription drugs, but the percentage could be higher because 13 percent of the data didn't specify the drugs involved. Three percent of the cases involved multiple narcotics, while the addictive heroin alone accounted for 16 percent of the emergencies.

Further analysis identified that overdose incidents are higher in urban areas (84 percent) than in the south (40 percent). Majority of the fatalities recorded were women, according to Healthday News.

"Opioid [narcotic] overdose exacts a significant financial and health care utilization burden on the U.S. health care system. Most patients in our sample overdosed on prescription opioids, suggesting that further efforts to stem the prescription opioid overdose epidemic are urgently needed," researchers wrote.

Painkiller overdoses have become one of the leading causes of injury deaths in the United States, and have caused a strain in the healthcare system. The number of cases involved in the study amounted to $1.4 billion.

About 41 percent were treated in the emergency room and dismissed, 55 percent were admitted, and 4 percent were transferred to an acute care hospital. Patients stayed in the hospital for about four days, and average costs totaled nearly $3,640.

To reduce the cost, experts suggested that law enforcement authorities should be trained with proper response techniques for overdose calls, and should be equipped with a drug that can reverse the effects of the narcotics. It will also decrease the number of hospital admissions, as well as save lives.

"It's absolutely critical that we equip them to respond appropriately," said U.S. Atty. Gen. Eric H. Holder Jr. to the Los Angeles Times.

Further details of the study were published in the Oct. 27 issue of JAMA Internal Medicine.