The Effects of Smoking and Smoking Cessation on Spine Surgery: A Systematic Review of the Literature.
This systematic review by Jackson and Devine provides us with a current review of the literature in regards to the effects of smoking and smoking cessation on spine surgery. While this review covers spine surgery in general, our reviewed focused solely on the effects related to cervical disc surgery.
There are several potential risks that have been discussed in the literature relating to the effects of smoking on cervical disc surgery. These include the potential for arthrodesis non-union, wound and medical complications, and inferior clinical outcomes.
In regards to arthrodesis rates, the authors reviewed 6 studies published between 1995 and 2014. All were either a retrospective case series or prospective comparative study. Findings varied based on study. The largest of the six studies was from Luszczyk et al (2013) which compared 417 nonsmokers to 156 smokers who underwent a single level ACDF (with allograft and plating). No significant differences in fusion rates were identified. In contrast, Hilibrand et al (2001) found lower fusion rates in smokers undergoing ACDF (81% nonsmokers vs. 62% smokers) but similar fusion rates for corpectomy. In general, as the authors of this paper have pointed out, the effects of smoking pose a greater risk of non-union for multilevel fusions than for a single level ACDF.
Limited evidence still exists looking at the effects of smoking on clinical outcomes from cervical disc surgery. Hilibrand (2001) found a higher percentage of excellent or good functional outcomes in nonsmokers than smokers (at 2 years post-op). Tetreault et al (2013) published a prospective, multi center study of 278 patients treated surgically for cervical spondylotic myelopathy. Using the Japanese Orthopaedic Association (JOA) score, the authors found that smokers were less likely to experience a successful outcome (at one year) than nonsmokers. Interestingly, fusion rates between smokers and nonsmokers were equivalent. As we have long suspected, factors other than arthrodesis status contribute to clinical outcome.
When should patients be advised to discontinue smoking prior to cervical surgery? This is a question that Jackson and Devine attempted to answer in this systematic review. Data is still lacking to provide a solid answer to this question. Looking at the data from 3 studies published in 2005 – 2012, the suggestion is that smoking cessation for 4 weeks pre-operatively is associated with decreased risk of infection, respiratory, and wound complications. While these results are findings are in-line with conventional wisdom, this data was not specifically taken from studies of cervical disc surgery.
In summary, this systematic review does provide us with some evidence on the effects of smoking and cervical disc surgery. Data is very limited and does not necessarily control for smoking amounts (packs per day) and consideration of other confounders that also may lower fusion rates and clinical outcomes. A great deal of what patients are told is largely anecdotal or based on investigations that either have methodological flaws or offer limited data. We know that nicotine exposure does not have any positive effects and therefore, we should continue to counsel our patients regarding the importance of smoking cessation.