people taking narcotics for chronic pain actually increased their use of
following bariatric surgery intended to reduce their weight and relieve their
pain, a new study shows.
Bariatric patients who
already were chronic users of opioid painkillers such as OxyContin and Vicodin
increased their drug intake by 13% the first year after surgery and by 18%
three years after, researchers report in the Journal of
the American Medical Association.
Weight loss associated with
procedures such as gastric bypass has been found to relieve chronic pain caused
by the stress that extra pounds place on the knees, back and other joints.
"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."
differ, but usually limit the amount of food you can consume. Some types of
surgery also change how food is digested and nutrients are absorbed.
Chronic narcotic users
The study involved
reviewing the medical records of more than 11 700 adults who had weight-loss
surgery between 2005 and 2009. About 8% of the patients were chronic
Researchers found that 77%
of those chronic users continued taking opioids during the year following their
surgery. What's more, over three years following the surgery their use of
opioids grew by 18%.
The amount of weight loss
associated with bariatric surgery did not seem to make a difference in their
drug use. Chronic use of morphine equivalents before and after surgery did not
differ between individuals who lost more than half their excess body-mass index
(BMI) versus those who lost less than half.
These findings should cause
doctors to reconsider the counselling they provide obese patients about the
pain-relieving benefits of bariatric surgery, Raebel said.
"We have patients who
have pain that simply doesn't respond to weight loss," she said. "If
the patient thinks that's the reason they're going to have bariatric surgery,
there should be some counselling to explain their pain may or may not get better
Reducing the demand for
chronic pain killers is a laudable goal, experts say. Since the 1980s, opioid
prescriptions in the United States have quadrupled, and accidental opioid
overdose deaths have also increased fourfold, according to an accompanying
Raebel said there are a
couple of possible explanations why narcotic use increased after weight-loss
surgery, starting with the way that obese people experience chronic pain.
"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." Their medication use might increase
to help them deal with their continued sensitivity to pain, she said.
These patients also may be
trying to overcome increased tolerance to narcotics. "If you continue to
take the drug, you have to take higher and higher dosages to get the same pain
relief," she said. "When you take higher and higher dosages, you may
further increase your pain sensitivity, which may increase your need to take
the drug even if your initial source of pain is reduced."
Bariatric physician Dr
Brian Sabowitz noted that such surgery can alter digestion of medications as
well as food.
"Narcotics may not be
absorbed the same way after a gastric bypass as they are before a gastric
bypass," said Sabowitz, who practices in San Antonio, Texas, and serves as
an adjunct assistant professor of medicine for the University of Texas Health
Science Centre in San Antonio. "Maybe one reason narcotic use increased is
because people were getting less narcotics [in their system]."
Another explanation could
be that these patients may have used non-steroidal anti-inflammatory drugs such
as ibuprofen or acetaminophen as their first line of treatment for pain, with
opioids on hand to help with pain flare-ups, Sabowitz said.
But people who have
bariatric surgery often are told to not use non-steroidal anti-inflammatory
drugs because they can thin the blood and cause suture bleeding. "You're
taking away their prime source of pain management," he said. "It
wouldn't be surprising if their back-up source became their prime source."
In any case, bariatric
doctors need to keep a more watchful eye on patients' drug use, Raebel said,
particularly if they were chronic users prior to surgery.
"We do need better
strategies for these folks," she said. "In some patients, that will
be how to best have an agreed-upon treatment plan that they will adhere to. In
others, it may be how to safely reduce the dosage and even stop the drug. But
it has to be individualised for each patient."
For more information on
weight loss surgery, visit the US
National Institutes of Health.