P146. Smoking is associated with poorer fusion, functional outcomes and lower satisfaction in non-diabetic patients undergoing single-level transforaminal lumbar interbody fusion

BACKGROUND CONTEXT Smoking is associated with increased risk of lumbar disc degeneration and inhibition of lumbar spinal fusion. There is conflicting data on the role of smoking on spinal surgery outcomes with some studies demonstrating that smokers tend to have poorer functional outcomes and satisfaction scores postoperatively, whereas others have demonstrated no significant associations between smoking and surgery outcomes. On a biomolecular level, smoking can negatively influence spinal fusion surgical outcomes through impedance of angiogenesis needed for fusion healing through vasoconstriction and interference of metabolic mediators that normally facilitate angiogenesis and osteogenesis. Previous studies suggest diabetes and smoking have a synergistic effect that contributes to poorer spinal surgery outcomes. However, relationship between non-diabetic smokers, fusion outcomes and patient reported outcomes is not well understood. PURPOSE This study seeks to examine if smoking influences patient-reported outcomes and fusion rates in patients undergoing a single level transfoaminal lumbar interbody fusion (TLIF) in non-diabetic patients. METHODS Prospectively collated data of 187 non-diabetic patients who underwent single level TLIF in an institution from 2012 to 2014 was reviewed. Smokers and non-smokers were identified. All patients were assessed pre-and postoperatively at 6 months and 2 years using the numberical pain rating scale (NPRS back and leg pain), Oswestry Disability Index (ODI), Short-Form 36 Physical and Mental Component Scores (SF-36 OCS and MCS) and North American Spine Society (NASS) score for neurogenic symptoms. Student's T-test and Chi-square test was used to compare parametric and proportion-based outcomes respectively between smokers and non-smokers. Multivariate logistic regression analysis was used to evaluate for any confounding factors. RESULTS Patients with smoking history were significantly younger and predominantly male as opposed to non-smokers. There were no significant differences in ODI, Sf-36 PCS/MCS and back/leg pain between smokers and non-smokers at 6 months and 2 years. However, significantly less smokers were satisfied with their surgical outcomes at 2-year follow up (p=0.003). In addition, there was a significant difference in fusion grades at 2 years postoperative (p=0.048) between smokers and non-smokers with poorer fusion rates in smokers. There was a trend toward greater minimal clinically important difference (MCID) attainment rates of SF-36 OCS in non-smokers as compared to smokers (84% vs 68%, p=0.05). Multivariate analysis performed showed patients with nil co-morbidities were likely to have better fusion outcomes (p=0.04) and hypertensive patients more likely to experience poorer fusion outcomes (p=0.02). CONCLUSIONS Smokers in our cohort were approximately 10 years younger than non-smokers, possibly explaining the deleterious effects of smoking on early development of lumbar spinal pathology. Smoking was associated with lower satisfaction and poorer radiological fusion after single-level TLIF. Non-diabetic ex-smokers and smokers with spinal pathology should be counselled accordingly preoperatively regarding their expectations post-surgery, in particular the likelihood of having poorer functional and satisfaction outcomes as well as poorer radiological fusion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.