Association between smoking and surgical site infection after spinal fusion surgery: a systematic review and meta-analysis.

objectiveEvidence on the relationship between smoking and postoperative surgical site infection (SSI) after spinal fusion is inconsistent. This systematic review and meta-analysis assessed whether smoking is associated with an increased risk of SSI following spinal fusion surgery.

methodsPubMed, Embase and the Cochrane Library were searched for observational studies published from 2010 to October 2025 comparing postoperative SSI between smokers and non-smokers undergoing spinal fusion; included studies used cohort or case-control designs. Risk ratios were pooled using a random effects model. Prespecified subgroup analyses were performed by spinal region, SSI definition, surgical indication, infection type, follow-up duration and smoking category. Meta-regression, leave-one-out analyses and the Peters test explored effect modifiers, robustness and small-study effects. The review was registered in PROSPERO (CRD420251181545).

resultsTwenty-six studies including 16,385 patients met the inclusion criteria. Smoking was associated with an increased risk of postoperative SSI (RR 1.28; 95% CI 1.08-1.53; p = 0.005). Significant associations were also seen with CDC criteria (RR 1.24; 95% CI 1.02-1.51; p = 0.03), in degenerative spine surgery (RR 1.76; 95% CI 1.17-2.67; p = 0.007), and in cohorts with at least 1 year of follow-up (RR 1.36; 95% CI 1.07-1.73; p = 0.01). Stratification by infection depth showed no significant differences. Sensitivity analyses supported the stability of the pooled effect.

conclusionSmoking is associated with a higher risk of SSI after spinal fusion. Because all included studies were observational, these findings indicate association rather than causation, and support incorporating smoking status into perioperative risk assessment and counseling.