Patients Use More Opioids After Weight-Loss Surgery

Three years after undergoing bariatric surgery, average daily morphine equivalents for chronic opioid users increased by 18% compared with intake a year before the surgery.

Although bariatric surgery has been shown to reduce chronic pain in obese patients, a new study reports that patients actually used more opioid painkillers after undergoing weight-loss surgery.

The study, published in the October 2, 2013, issue of the Journal of the American Medical Association, assessed chronic use of opioids prescribed to bariatric surgery patients to determine whether painkiller use decreased after surgery. The retrospective cohort study enrolled 11,719 patients aged 21 and older from a distributed health network made up of 10 health care systems throughout the country. All patients had a body mass index (BMI) of 30 or greater, underwent bariatric surgery between 2005 and 2009, and were evaluated 1 year before and 1 year after surgery.

Opioid use was measured in morphine equivalents for the year before and the year after surgery. Patients were classified as having chronic, some, or no opioid use based on the total amount of opioids dispensed during the year before surgery. Patients were identified as chronic users if they were dispensed opioids 10 or more times over 90 or more days or were dispensed at least a 120-day supply at one time. The effects of weight loss, preoperative chronic pain, or depression on postoperative opioid use were also studied.

During the year before surgery, 56% of patients used no opioids, 36% used some opioids, and 8% were chronic opioid users. Among patients identified as chronic opioid users before surgery, 77% continued to be chronic users a year after surgery, 20% continued to use some opioids, and 3% stopped taking opioids altogether. Not only did a majority of chronic users continue to take opioids after surgery, they went on to take larger doses. Average daily morphine equivalents among these patients increased from 45.0 mg the year before surgery to 51.9 mg the year after surgery—a 13% increase. Three years after surgery, average daily morphine equivalents for these patients had increased by 18%.

The study also found that increases in opioid use after surgery were similar among patients who lost more than 50% of excess BMI and among those who lost 50% or less of excess BMI. Whether patients had depression or chronic pain diagnosed before surgery had no effect on postoperative chronic opioid use.

Although the researchers expected to find a decrease in opioid use after bariatric surgery, in an accompanying editorial, Daniel P. Alford, MD, MPH, suggests that the results of the study are not terribly surprising. He notes that several factors for both patients and clinicians influence long-term opioid use and decisions to decrease use over time. Although bariatric surgery often reduces pain, it has not been shown to eliminate pain completely. Therefore, patients who have suffered from chronic pain for years may be hesitant to discuss decreasing a successful treatment with their health care provider.

Clinicians may also avoid talking about opioid use as there are minimal guidelines about when and how to decrease use of the drugs and these conversations can be time-consuming and emotional for patients. Dr. Alford writes that the study reveals “the need to know if, when, and how to safely and effectively taper or discontinue opioid therapy for patients with chronic pain.”