- Design
- Retrospective propensity-matched cohort, electronic records network
- Population
- 1,064 head and neck free flap patients (532 cannabis users, 532 non-users)
- Primary outcome
- Opioid use 3–12 months after surgery
- Effect
- RR 1.35 (95% CI 1.13–1.62) at 6–9 months; adjusted HR 1.42
Using a large US electronic records network, this study identified head and neck cancer patients having free flap reconstruction between 2005 and 2025 and propensity-matched 532 with a history of cannabis use to 532 without, on demographics, other substance use and tumour characteristics.
Cannabis users were more likely to still be taking opioids at 3–6 months (RR 1.19), 6–9 months (RR 1.35) and 9–12 months (RR 1.26), and the association persisted after adjusting for behavioural health conditions (HR 1.42). They were also more likely to be gastrostomy dependent at three months (RR 1.56). Tracheostomy dependence did not differ.
This is a reason to ask about cannabis use preoperatively and to plan pain management and opioid weaning with it in mind. It is observational and relies on coded cannabis use, which undercounts, and it cannot show cannabis itself causes prolonged opioid use.
- Ask about cannabis use at the preoperative assessment for major head and neck surgery.
- Plan multimodal analgesia and an opioid weaning schedule in advance for cannabis users.
- Arrange closer follow-up of opioid use after discharge in this group.
- Involve pain or addiction services early when prolonged opioid use develops.
Why it matters
It identifies a group at higher risk of long-term opioid use before surgery starts.
Don't overread it
This was observational with coded exposure; it shows association, not that cannabis causes prolonged opioid use.
The statistics, in plain English
Risk ratios of 1.2–1.35 mean about 20–35% more cannabis users were still taking opioids months later. The adjusted hazard ratio was reported with a 90% interval rather than the usual 95%, which makes it look a little more certain than it would otherwise.
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