Cannabis users stayed on opioids longer after head and neck free flap surgery

Design

Retrospective propensity-matched cohort, TriNetX database

Population

1,064 patients having head and neck free flap reconstruction (532 cannabis users)

Primary outcome

Opioid use 3 to 12 months after surgery

Effect

6 to 9 months RR 1.35 (1.13 to 1.62); adjusted HR 1.42 (90% CI 1.14 to 1.76)

This retrospective study used the TriNetX database to identify patients having head and neck free flap reconstruction between 2005 and 2025, and matched 532 cannabis users with 532 non-users on demographics, other substance use and tumour characteristics.

Cannabis users were more likely to be using opioids at three to six months (RR 1.19, 95% CI 1.05 to 1.36), six to nine months (RR 1.35, 1.13 to 1.62) and nine to twelve months (RR 1.26, 1.04 to 1.52). They were also more often gastrostomy-dependent at three months (RR 1.56, 1.19 to 2.04). Tracheostomy dependence did not differ. After adjustment for behavioural health comorbidities, cannabis use remained associated with prolonged opioid use (HR 1.42, 90% CI 1.14 to 1.76).

The association is consistent and fits what is known about cross-tolerance and altered pain processing in regular cannabis users. It cannot show that cannabis causes prolonged opioid use, because database coding of cannabis use is crude and residual confounding is likely. Its practical value is in identifying a group worth planning for before surgery.

• Ask about cannabis use, including frequency, at the preoperative assessment for head and neck reconstruction.
• Consider early involvement of the acute pain team for regular cannabis users.
• Plan multimodal and opioid-sparing analgesia from the outset in this group.
• Set a clear opioid tapering plan and review date at discharge.
• Watch swallowing recovery closely, since gastrostomy dependence was higher at three months.

Why it matters

Cannabis use is a modifiable, askable risk marker for long-term opioid use after major head and neck surgery.

Don't overread it

Database codes for cannabis use are crude, so this association cannot show that cannabis itself prolongs opioid use.

The statistics, in plain English

A risk ratio of 1.35 at six to nine months means about a third more cannabis users were still on opioids. The Cox model reports a 90% rather than the usual 95% interval, which makes the result look more precise than a standard interval would.

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