Initially, researchers assumed that when patients underwent weight loss surgery, they would decrease their dependence on pain medications over time. The reason for their assumption: Obese patients who shed pounds should experience a reduction in pain caused by excess weight in areas such as the knees and back. Instead, however, a new study has revealed that weight loss surgery actually may increase dependence on pain killers, reported U.S. News on October 1.
"Our premise was that because patients who are undergoing bariatric surgery were undergoing such dramatic weight loss, whatever chronic pain they were going through would be relieved and their need for medication would be reduced," said study author Marsha Raebel, of Kaiser Permanente Colorado in Denver. "We were very surprised to find we were totally wrong. Not only did their chronic use of opioids not go down, it actually went up."
Researchers discovered that bariatric patients who already used opioid painkillers such as OxyContin and Vicodin increased their drug intake by 13 percent during the first year after surgery. And rather than decrease their dependence as they lost more weight over time, these patients had increased their drug intake by 18 percent three years after.
In the study, which was reported in the Oct. 2 issue of the Journal of the American Medical Association, researchers emphasized that weight loss resulting from procedures such as gastric bypass typically relieves pain linked to the stress that extra pounds place on the knees, back and other joints. But that relief did not influence how much pain medication the patients took.
"We have patients who have pain that simply doesn't respond to weight loss," Raebel said. "If the patient thinks that's the reason they're going to have bariatric surgery, there should be some counseling to explain their pain may or may not get better after surgery."
And the experts stress that setting a goal of taking fewer chronic pain killers is essential. Since the 1980s, opioid prescriptions in the nation have quadrupled, as has accidental opioid overdose deaths.
Raebel believes that obese people actually experience pain in a different way.
"Folks who are obese are more sensitive to pain and have lower pain thresholds than people who aren't obese," she said. "This altered pain processing continues even after they undergo bariatric surgery." Therefore, she thinks that their drug usage might increase to help them deal with their continued sensitivity to pain.
Bariatric physician Dr. Brian Sabowitz offered another interpretation of the study.
"Narcotics may not be absorbed the same way after a gastric bypass as they are before a gastric bypass," said Dr. Sabowitz, who practices in San Antonio, Texas, and serves as an adjunct assistant professor of medicine for the University of Texas Health Science Center in San Antonio. "Maybe one reason narcotic use increased is because people were getting less narcotics [in their system]."