Review article A systematic review and meta-analysis of wound drains in non-instrumented lumbar decompression surgery Christopher L. Davidoff a,b,⇑ , Jeffrey M. Rogers c , Mary Simons c , Andrew S. Davidson a,b,c a Macquarie Neurosurgery, Macquarie University Hospital, Sydney, New South Wales 2109, Australia b Department of Neurosurgery, Nepean Hospital, Penrith, New South Wales 2750, Australia c Department of Clinical Medicine, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales 2109, Australia article info Article history: Received 18 January 2018 Accepted 9 April 2018 Available online xxxx Keywords: Epidural hematoma Laminectomy Microdiscectomy Systematic review Wound drain abstract Wound drains are routinely used in lumbar decompressive surgery (LDS). However, it remains unclear whether this practice helps to prevent symptomatic epidural hematoma formation and associated com- plications, particularly following non-instrumented procedures. A systematic review and meta-analysis was therefore completed to critically appraise the literature. The search protocol was conducted using the Ovid MEDLINE, EMBASE, Scopus, Cochrane Library, and Google Scholar databases. Articles meeting the following criteria were included: (i) examined patients undergoing LDS; (ii) included cases receiving post-operative wound drains; (iii) detailed adverse outcomes including symptomatic epidural hemato- mas or wound infection; and (iv) were published in English in a peer-reviewed journal. Pooled risk differences (RD) for adverse outcomes were calculated using Comprehensive Meta-Analysis software. Three Level 1b prospective randomized studies and five Level 2b retrospective cohort studies were included, from which 5327 cases were identified as having received a surgical drain and 773 were identified as having received no drainage following non-instrumented LDS. There was no difference between groups in the risk of symptomatic epidural hematoma (RD = 0.02; 95% CI 0.02  0.06, p = 0.28) or post-operative infection (RD = 0.00; 95% CI 0.01  0.01, p = 0.91). In conclusion, symptomatic epidural hematomas and infection are rare following non-instrumented LDS, with incidence rates unaffected by the routine use of wound drainage. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction A symptomatic epidural hematoma is a rare but devastating post-operative complication of spinal surgery. First described by Jackson in 1869 [1], epidural hematomas can occur in the setting of anticoagulation or use of antiplatelet agents [2–5], and are thought to be caused by rupture of the internal vertebral venous plexus of Batson [6]. The documented incidence of symptomatic epidural hematomas after spinal surgery varies across studies, from 0.1% to 0.2% of surgical cases [2,3,7,8], although spinal sur- geons tend to estimate the risk to be much higher [9]. Compression of the neural structures, occurring as a consequence of epidural hematoma can result in permanent neurological damage if not rapidly detected and addressed [10]. Non-steroidal anti- inflammatory drug (NSAID) use, Rh positive blood group, age over 60 years, pre-operative coagulopathy, hemoglobin less than 10 g/ dL, intra-operative blood loss greater than 1L, multi-level proce- dures, and an international normalized ratio greater than 2.0 in the first 48 h after surgery have all been shown to increase the risk of a patient suffering an epidural hematoma [2,7,8,11]. To help prevent formation of post-operative epidural hemato- mas, wound drains are commonly used in spinal surgery [12], although the evidence to support this practice remains unclear [13]. Three recent reviews investigated the relationship between wound drains and adverse outcomes following lumbar surgery [14–16]. However, five of the eight studies included in the system- atic review by Zijlmans and colleagues did not use wound drains. The rationale for inclusion of such studies was unclear, and con- founded conclusions that use of a wound drain does not affect the incidence of either post-operative epidural hematoma or wound infection, as the authors themselves acknowledged [15]. Liu and colleagues’ meta-analysis and Waly and colleagues’ sys- tematic review also concluded wound drains in posterior spinal surgery do not influence the incidence of epidural hematoma, infection, blood loss, or neurological injury [14,16]. However, both reports included patients undergoing spinal fusion surgery, https://doi.org/10.1016/j.jocn.2018.04.038 0967-5868/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Macquarie Neurosurgery, Suite 201, 2 Technology Place, Macquarie University, Sydney, New South Wales 2109, Australia. E-mail address: CDavidoff@mqneurosurgery.com (C.L. Davidoff). Journal of Clinical Neuroscience xxx (2018) xxx–xxx Contents lists available at ScienceDirect Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn Please cite this article in press as: Davidoff CL et al. A systematic review and meta-analysis of wound drains in non-instrumented lumbar decompression surgery. J Clin Neurosci (2018), https://doi.org/10.1016/j.jocn.2018.04.038