Bariatric Surgery and Post-Op Pain Meds

Opioid use in obese patients after bariatric surgery examined in new study

(RxWiki News) Obesity doesn't just lead to conditions that can cause issues over time; it can also bring about daily pain in the body. This pain, often in the joints or the back, may lead some obese people to rely on certain pain medications — a topic explored in a new study.

The authors of this new study wanted to see if patients who went through bariatric surgery to treat obesity, and potentially pain, were relying on a certain kind of pain medication called opioids after their surgery.

The study found that 77 percent of people who used opioids chronically prior to surgery continued to do so afterwards, and for most patients, their use increased.

"Exercise several times a week to stay fit and healthy."

According to the authors of the study, the long-term use of opioid analgesics (including Vicodin and OxyContin), taken for chronic musculoskeletal and nonspecific pain, has recently increased in the US.

Bariatric surgery, which changes the anatomy of the digestive system in order to treat obesity, often helps with other conditions that go along with obesity, including metabolic problems, cardiovascular issues and chronic pain, say the study authors, who were led by Marsha A. Raebel, PharmD, of Kaiser Permanente Colorado in Denver.

The study authors wanted to see if opioid use was reduced post-surgery for patients undergoing a bariatric operation, and if issues like postoperative weight loss, postoperative chronic pain and postoperative depression had an effect on opioid use.

Dr. Raebel and colleagues utilized the Scalable Partnering Network for comparative effectiveness research (SPAN), which gathers clinical information from ten sites spread across the US to identify 11,719 participants who had bariatric surgery between January 1, 2005 and December 31, 2009.

Participants were all aged 21 or older and considered obese at the time of their surgery, meaning they had a body mass index (BMI; a measurement of body fat based on weight and height) over 30.

Participants were assessed for opioid use one year before and one year after their surgery.

The study authors defined chronic opioid use as receiving ten or more dispensings of the medication from a pharmacy over a 90 day period or longer, or as receiving dispensings of at least a 120 day supply during the year before surgery. The use of opioids was measured as morphine equivalents.

The researchers did not include opioid use during the 30 days immediately after surgery in their findings, as opioid use might have changed during this period while participants coped with postoperative pain. 

In the year prior to bariatric surgery, 56 percent of participants did not use opioids, 36 percent used some opioids and 8 percent of the participants were considered chronic opioid users. Of the participants who used opioids chronically prior to surgery, 77 percent continued their chronic use of opioids during the year after surgery.

In comparing the chronic opioid users' use of the medication before and after their surgeries, the amount of opioid use increased by 13 percent in the first postoperative year and 18 percent over three postoperative years.

Prior to surgery, average daily morphine equivalents for the chronic opioid users was 45 milligrams a day. After surgery, this increased to 51.9 milligrams a day. Among this group with chronic opioid use, there was no change in morphine equivalents seen between those who lost more than 50 percent of their excess BMI and those who lost 50 percent or less.

Dr. Raebel and colleagues found that neither postoperative depression nor a postoperative diagnosis of chronic pain seemed to influence changes between chronic opioid use before and after surgery.

"...[I]n this cohort of patients who underwent bariatric surgery, there was greater chronic use of opioids after surgery compared with before," the study authors explained. "Preoperative chronic opioid users required increased morphine equivalents after surgery. These findings suggest the need for proactive management of chronic pain in these patients after surgery."

This study will be published October 2 in the Journal for the American Medical Association (JAMA).

Several study authors reported receiving grants from or being employed by a variety of organizations, including the Agency for Healthcare Research and Quality, the US Food and Drug Administration, Kaiser Foundation Research Institute and Pfizer, Inc., among others.

Review Date: 
September 27, 2013