Relationship between smoking and postoperative complications of cervical spine surgery: a systematic review and meta-analysis

To determine whether smoking has adverse effects on postoperative complications following spine cervical surgery (PROSPERO 2021: CRD42021269648). We searched PubMed, Embase, Cochrane Library, and Web of Science through 13 July 2021 for cohort and case-control studies that investigated the effect of smoking on postoperative complications after cervical spine surgery. Two researchers independently screened the studies and extracted data according to the selection criteria. The meta-analysis included 43 studies, including 27 case-control studies and 16 cohort studies, with 10,020 patients. Pooled estimates showed that smoking was associated with overall postoperative complications (effect estimate [ES] = 1.99, 95% confidence interval [CI]: 1.62-2.44, p < 0.0001), respiratory complications (ES = 2.70, 95% CI: 1.62-4.49, p < 0.0001), reoperation (ES = 2.06, 95% CI: 1.50-2.81, p < 0.0001), dysphagia (ES = 1.49, 95% CI: 1.06-2.10, p = 0.022), wound infection (ES = 3.21, 95% CI: 1.62-6.36, p = 0.001), and axial neck pain (ES = 1.98, 95% CI: 1.25-3.12, p = 0.003). There were no significant differences between the smoking and nonsmoking groups in terms of fusion (ES = 0.97, 95% CI: 0.94-1.00, p = 0.0097), operation time (weighted mean difference [WMD] = 0.08, 95% CI: -5.54 to 5.71, p = 0.977), estimated blood loss (WMD = -5.31, 95% CI: -148.83 to 139.22, p = 0.943), length of hospital stay (WMD = 1.01, 95% CI: -2.17 to 4.20, p = 0.534), Visual Analog Scale-neck pain score (WMD = -0.19, 95% CI: -1.19 to 0.81, p = 0.707), Visual Analog Scale-arm pain score (WMD = -0.50, 95% CI: -1.53 to 0.53, p = 0.343), Neck Disability Index score (WMD = 11.46, 95% CI: -3.83 to 26.76, p = 0.142), or Japanese Orthopedic Association Scores (WMD = -1.75, 95% CI: -5.27 to 1.78, p = 0.332). Compared with nonsmokers, smokers seem to be more significantly associated with overall complications, respiratory complications, reoperation, longer hospital stay, dysphagia, wound infection and axial neck pain after cervical spine surgery. It is essential to provide timely smoking cessation advice and explanation to patients before elective cervical spine surgery.