Smoking is a strong predictor of patient-reported outcomes following anterior cervical discectomy with fusion

PHILADELPHIA — Results of a study presented here indicate that patients who smoke have lower patient-reported outcomes following anterior discectomy and fusion, and that smoking may be a predictor of patients who may have poorer self-reported results.

“The preliminary results of this multi-centered, randomized controlled data indicate that smoking affects patient-reported outcomes,” said Paul M. Arnold, MD, FACS, at the 78th Annual Meeting of the American Association of Neurological Surgeons (AANS). “In virtually every one of these subjective parameters, the nonsmokers did better.”

Although many studies have shown that smoking affects the rates of fusion following spinal fusion surgery, little information is available on its effects on patient-reported outcomes, he said.

IDE trial

Data for the study were obtained from a larger randomized, controlled, multi-center, prospective FDA Investigational Device Exemption study to assess the safety and efficacy of a bone graft used for single-level anterior discectomy and fusion (ACDF). Overall, 90 patients were randomized to receive the allograft bone or local autologous bone inside a structural allograft during the single-level ACDF procedure for degenerative disc disease. Follow-up data at 1-year postoperative were available for 60 patients, of whom 17% were smokers.

Self-assessment tests included the Neck Disability Index (NDI), Visual Analog Scale (VAS) pain score and the SF-36 mental and physical component scores.

Test results

According to the study abstract, NDI improvement was 7.12 points lower in smokers than nonsmokers; VAS scores for arm pain improvement were 2.48 points lower in smokers than nonsmokers; VAS scores for neck pain were 3.15 points lower in smokers than nonsmokers; SF-36 physical scores were 6.44 points lower in smokers than nonsmokers and SF-36 mental component scores were 6.55 points lower in smokers than nonsmokers.

“The negative association of smoking and patient-reported outcomes remained significant after adjusting for potential confounders,” Arnold said.

Smoking emerged as a strong predictor of patient-reported outcomes of ACDF, he reported.

Reference:
Arnold PM, Fehlings M, Sasso R. Smoking is a predictor of response to ACDF with instrumentation in patients with single-level DDD. Paper #662. Presented at the 78^th Annual American Association of Neurological Surgeons. May 1-5, 2010. Philadelphia.

The effect of smoking on fusion is well documented. Smoking has resulted in a diminished fusion rate in every large study in spine surgery. Although smoking has been shown to adversely affect fusion rates, the effect of smoking on clinical outcomes has not been widely studied. This paper attempted to clarify whether smoking leads to adverse clinical outcomes.

This is a general single-level ACDF model, in which it is typically difficult to show differences because results are usually quite positive in each of the groups — that made it a good model for this question. Their results demonstrated statistically significant adverse results reported in VAS and SF-36 in smokers compared to nonsmokers.

The only concern I have is if the authors analyzed whether fusion status had any effect on the outcomes. The reason is, did these smokers have poorer outcomes because they were smokers, or because they had nonunions. I think that is something that will be an important issue to ferret out over time — is this a problem of nonunion or a problem actually of smoking? I look forward to longer-term results of this study being presented.

– Robert F. Heary, MD
Discussant of the paper at the AANS meeting

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