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Use of opioid medications to treat chronic pain does not decline after bariatric surgery for obesity, a new study published in JAMA shows. Indeed, many patients increase their opioid intake after surgery.

The usage of opioids is increasing in North America, even though chronic use is associated with abuse, accidental overdose and death, and the long-term efficacy of these drugs remains unclear. People with obesity often suffer from chronic pain, such as knee osteoarthritis and back pain. Raebel et al. speculated that weight loss after bariatric surgery could be associated with reduced pain and opioid use. “To our knowledge, this is the first study evaluating chronic opioid use in the bariatric surgery population,” says lead investigator Marsha A. Raebel.

In a retrospective cohort study, the researchers investigated 11,719 individuals aged ≥21 years who underwent bariatric surgery between 2005–2009. The study was conducted at 10 demographically and geographically varied US health-care systems, and people with a BMI <30 kg/m2 in the year before surgery were excluded. The patients were assessed 1 year before and at least 1 year after surgery. The database contained information on opioid dispensing, which was used to determine opioid usage. Chronic opioid users were defined as patients having ≥10 opioid dispensings over ≥90 days or at least a 120-day supply in the year prior to bariatric surgery.

Before bariatric surgery, 56% of the patients did not use opioids, 36% used some opioids, and 8% were chronic opioid users. Among the chronic users, 77% continued opioid use after surgery. Moreover, in this group, the usage increased by 13% and 18% at 1 year and 3 years after surgery, respectively.

“One possible explanation [for the increased use of opioids after surgery] is that some patients probably had pain unresponsive to weight loss but potentially responsive to opioids,” says Raebel. “This finding suggests the need for better pain management in these patients following surgery.”

The researchers plan to continue studying the use of opioids in individuals undergoing bariatric surgery to gain a better understanding of the risks and benefits of this treatment. “If opioids are to be used chronically, it should be with a treatment plan in place that has been agreed-upon by the physician and patient and is monitored routinely,” Raebel concludes.