The effect of marijuana use on short-term outcomes with bariatric surgery.

Background: Despite increasing marijuana use nationwide, there are limited data on implications of marijuana use on bariatric surgery outcomes.

Objective: We investigated associations between marijuana use and bariatric surgery outcomes.

Setting: Multicenter statewide study utilizing data from the Michigan Bariatric Surgery Collaborative, a payor-funded consortium including over 40 hospitals and 80 surgeons performing bariatric surgery statewide.

Methods: We analyzed data from the Michigan Bariatric Surgery Collaborative clinical registry on patients who underwent a laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass between June 2019 and June 2020. Patients were surveyed at baseline and annually on medication use, depression symptoms, and substance use. Regression analysis was performed to compare 30-day and 1-year outcomes between marijuana users and nonusers.

Results: Of 6879 patients, 574 reported baseline marijuana use and 139 reported use at baseline and 1 year. Marijuana users were more likely to be current smokers (14% versus 8%, P < .0001), screen positive for alcohol use disorder (20.0% versus 8.4%, P < .0001), and score higher on the Patient Health Questionnaire-8 (6.1 versus 3.0, P < .0001). There were no statistically significant differences in 30-day outcomes or co-morbidity remission at 1 year. Marijuana users had higher adjusted total mean weight loss (47.6 versus 38.1 kg, P < .0001) and body mass index reduction (17 versus 14 kg/m, P < .0001).

Conclusions: Marijuana use is not associated with worse 30-day outcomes or 1-year weight loss outcomes and should not be a barrier to bariatric surgery. However, marijuana use is associated with higher rates of smoking, substance use, and depression. These patients may benefit from additional mental health and substance abuse counseling.