While it might make sense that losing weight lessens the need for pain relief because some pain syndromes are related to obesity, a new study showed that chronic opioid users not only continued to take these drugs after bariatric surgery but also increased their use.
Of those patients who took opioids chronically before surgery, 77% continued such use afterwards, increasing it by 13% in the first year, and by 18% by 3 years.
"We anticipated weight loss after bariatric surgery would result in reduced pain and opioid use among patients with chronic pain," the study authors, led by Marsha A. Raebel, PharmD, Institute for Health Research, Kaiser Permanente Colorado, Denver, concluded. "However, patients with and without preoperative chronic pain, depression diagnosis, or both had similar increases in postoperative chronic opioid use after surgery as those without chronic pain or depression."
The authors say these findings suggest the need for proactive management of chronic pain in these patients after surgery.
The study was published in the October 2 issue of JAMA.
The retrospective cohort study included data on 11,719 patients from 10 sites included in the shared Scalable Partnering Network (SPAN) database who underwent bariatric surgery between January 1, 2005, and December 31, 2009.
During the year before bariatric surgery, 56% of patients had no opioid use, 36% had some opioid use (defined as 1 to 9 dispensings or a 1 to less than 120-day supply dispensed), and 8%, or 933 patients, had chronic opioid use, defined as having 10 or more opioid dispensings over 90 or more days or at least a 120-day supply of opioids dispensed sometime in the year before bariatric surgery.
Among patients with chronic opioid use before surgery, 77% (95% confidence interval [CI], 75% - 80%) continued chronic use the year after surgery while 20% (95% CI, 17% - 22%) changed to some use and 3% (CI, 2% - 3%) had no opioid use.
The 933 chronic presurgery opioid users increased their opioid use after weight loss surgery. The incidence rate ratio for morphine equivalents (which takes into account quantity and strength), compared with preoperative levels, was 1.13 (95% CI, 1.06 - 1.20) after the first year and 1.18 (95% CI, 1.11 - 1.26) 3 years after surgery.
Furthermore, after surgery, chronic opioid users were dispensed higher-potency opioids than before surgery.
Significant Weight Loss
Chronic opioid use continued even among those who had significant weight loss. The study found that adjusted relative postoperative increases in total morphine equivalents didn't differ between individuals who lost more than 50% of their excess body mass index (BMI) compared with those who lost 50% or less.
As well, neither preoperative depression nor chronic pain diagnosis influenced changes in chronic opioid use.
Multiple factors may contribute to increasing opioid use, said the authors. Obese patients have more pain sensitivity and lower pain detection thresholds than normal weight patients, and altered pain processing may persist after bariatric surgery.
Long-term opioid use may lead to tolerance with users needing higher dosages to achieve the same pain relief, and escalating dosages may increase pain sensitivity even when the initial cause has resolved.
Doctors have relatively few options for pain relief in bariatric surgery patients suffering pain. Nonsteroidal anti-inflammatory agents should be avoided and acetaminophen are relatively ineffective in this population, said the authors.
In an accompanying editorial, Daniel P. Alford, MD, Boston Medical Center, Boston University School of Medicine, Massachusetts, said there are "powerful" patient and clinician factors working against decreasing opioid use.
Since opioids are typically the treatment of last resort, have federal and state laws and regulations limiting how they can be prescribed, and are becoming more difficult to obtain in certain settings (for example, emergency departments), it's not surprising that these drugs are perceived to be the most powerful and desirable of pain killers, said Dr. Alford.
"Why would any patients want to risk losing access to this powerful therapy when they still have pain?"
While patients are reluctant to discuss tapering or discontinuing opioids with their clinicians, physicians themselves face many barriers that prevent them from discontinuing opioids, said Dr. Alford.
Such barriers include a lack of knowledge, confidence, and skill in how to taper opioids safely and effectively in patients who are physically dependent, and a lack of readily available evidence-based guidance about tapering opioids in patients with chronic pain.
"Although core competencies for pain management are being developed, knowing when and how to continue, change, or discontinue opioid therapy must be included in all clinical education efforts," he concludes.
All authors report receipt of grant support from the Agency for Healthcare Research and Quality (AHRQ). Dr. Raebel reports grant and contract support from AHRQ and the US Food and Drug Administration.
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Cite this: Opioid Use Increases in Some Patients After Bariatric Surgery - Medscape - Oct 08, 2013.