Marijuana's Influence on Pain Scores, Initial Weight Loss, and Other Bariatric Surgical Outcomes

Pain management can be challenging following bariatric surgery, and patients with obesity tend to increase opioid use after undergoing surgery. This report quantifies marijuana (MJ) use and its relationship to pain and other surgery-related outcomes in a population from a state that has legalized MJ.

Data were collected for consecutive patients undergoing weight reduction surgeries between May 1, 2014 and July 31, 2015. Demographics, preoperative comorbidities, medications, and perioperative opioid use were analyzed. The primary outcome evaluated was inpatient opioid pain medication use quantified using natural log morphine equivalents. Secondary outcomes included percentage of total body weight loss after three months, postoperative complications, and changes in medical comorbidities.

A total of 434 patients, among whom 36 (8.3%) reported MJ use, comprised the study population. Perioperative opioid requirements were significantly higher in the MJ-user group (natural log morphine equivalents of 3.92 vs 3.52, p = 0.0015) despite lower subjective pain scores (3.70 vs 4.24, p = 0.07). MJ use did not affect percentage of 90-day total body weight loss, development of postoperative complications, or improvement in medical comorbidities.

Perioperative opioid use was significantly higher in the MJ-user group despite lower subjective pain scores. The difference in opioid requirements suggests an interaction between MJ use and opioid tolerance or pain threshold. The percentage of total body weight loss, improvement in medical comorbidity, and incidence of postoperative complications at 90-day follow-up were not affected by MJ use in this cohort analysis.