Higher Opioid Use After Bariatric Surgery Did Not Prove Cannabis Caused Tolerance

A surgical cohort found higher perioperative opioid use among patients reporting marijuana use. The finding did not independently establish that cannabis caused opioid tolerance, and the accompanying pain-score difference was not statistically significant.

The comparison involved existing cannabis use

The study included 434 bariatric-surgery patients, thirty-six of whom reported marijuana use. Investigators analyzed perioperative opioid requirements and other outcomes. Cannabis use was not randomly assigned.

The statistical results differed

Opioid requirements were significantly higher in the marijuana-user group. Reported pain scores were numerically lower, but the abstract gives a p value of 0.07 for that comparison. A numerical difference at that value should not be presented as a significant reduction in pain.

Other outcomes did not show an association

The abstract reported no effect on ninety-day weight loss, postoperative complications or improvement in medical comorbidities in this cohort. These negative findings do not establish equivalence or exclude smaller differences, particularly with a relatively small cannabis-user group.

Higher opioid administration could reflect several clinical and patient factors. It is not a direct receptor-tolerance assay, and it does not by itself prove greater pain sensitivity or a causal drug interaction. The useful distinction is between a measured treatment requirement and a proposed explanation for it. The study can inform further investigation without determining an individual patient's medication needs or proving that cannabis caused a particular postoperative outcome.

Related: interpreting cannabis tolerance claims.

Research cited

Bauer FL; Donahoo WT; Hollis HW; Tsai AG; Pottorf BJ; Johnson JM; Silveira LJ; Husain FA. Marijuana's Influence on Pain Scores, Initial Weight Loss, and Other Bariatric Surgical Outcomes. The Permanente journal (2018). doi:10.7812/TPP/18-002. Findings discussed from the study abstract.