- Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York, United States
Keaton F. Piper
Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York, United States
DOI:10.4103/sni.sni_306_17Copyright: © 2017 Surgical Neurology International This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Keaton F. Piper, Samuel B. Tomlinson, Gabrielle Santangelo, Joseph Van Galen, Ian DeAndrea-Lazarus, James Towner, Kristopher T. Kimmell, Howard Silberstein, George Edward Vates. Risk factors for wound complications following spine surgery. 01-Nov-2017;8:269
How to cite this URL: Keaton F. Piper, Samuel B. Tomlinson, Gabrielle Santangelo, Joseph Van Galen, Ian DeAndrea-Lazarus, James Towner, Kristopher T. Kimmell, Howard Silberstein, George Edward Vates. Risk factors for wound complications following spine surgery. 01-Nov-2017;8:269. Available from: http://surgicalneurologyint.com/surgicalint-articles/risk-factors-for-wound-complications-following-spine-surgery/
Background:Wound complications, including surgical site infections (SSIs) and wound dehiscence, are among the most common complications following spine surgery often leading to readmission. The authors sought to identify preoperative characteristics predictive of wound complications after spine surgery.
Methods:The American College of Surgeons National Surgical Quality Improvement Program database for years 2012–2014 was reviewed for patients undergoing spine surgery, defined by the Current Procedural Terminology codes. Forty-four preoperative and surgical characteristics were analyzed for associations with wound complications.
Results:Of the 99,152 patients included in this study, 2.2% experienced at least one wound complication (superficial SSI: 0.9%, deep SSI: 0.8%, organ space SSI: 0.4%, and dehiscence: 0.3%). Multivariate binary logistic regression testing found 10 preoperative characteristics associated with wound complications: body mass index ≥30, smoker, female, chronic steroid use, hematocrit 3 hours. A risk score for each patient was created from the number of characteristics present. Receiver operating characteristic curves of the unweighted and weighted risk scores generated areas under the curve of 0.701 (95% CI: 0.690–0.713) and 0.715 (95% CI: 0.704–0.726), respectively. Patients with unweighted risk scores >7 were 25-fold more likely to develop a wound complication compared to patients with scores of 0. In addition, mortality rate, reoperation rate, and total length of stay each increased nearly 10-fold with increasing risk score.
Conclusion:This study introduces a novel risk score for the development of wound dehiscence and SSIs in patients undergoing spine surgery, using new risk factors identified here.
Keywords: Spine surgery, surgical site infection, wound dehiscence, wound complication, risk factors
The increasing cost associated with spine surgery is a well-known problem affecting the United States (US) healthcare system; this is becoming more important with the increasing prevalence of spine surgeries. From 2002 to 2007, the rate of complex spine surgery increased almost 15-fold in the Medicare population.[
Among the most common postoperative complications associated with readmissions are wound complications, including surgical site infections (SSIs) and dehiscence.[
Given the relatively low percentage of wound infections and dehiscence in spine surgery, it is difficult to develop a cost-effective intervention for reducing these rates. One approach to this problem is to identify patients who are at an increased risk of wound complications and may benefit from more intensive preventative wound care. There have been various effective interventions aimed at reducing wound complications.[
In the present study, we sought to determine preoperative characteristics independently associated with wound complications in patients undergoing spine surgery. Using these factors, we developed a novel risk score for this cohort that may be used to calculate a patient's risk of developing a wound complication including organ-space SSI, deep incisional SSI, superficial SSI, or dehiscence. Further validation of this methodology may allow clinicians to anticipate high-risk cases and adjust perioperative management with the goal of reducing occurrences of wound complications.
Data were collected from the National Surgical Quality Improvement Project (NSQIP) dataset during the years 2012–2014. Organized by the American College of Surgeons (ACS), the NSQIP database is a collection of perioperative data sourced from deidentified surgical cases at over 700 hospitals in the US. Data allocation at each participating site is performed by an ACS-trained Surgical Clinician Reviewer (SCR), who collects information in a standardized manner, maintains a degree of separation from the hospital's physicians, and undergoes regular audits.[
Univariate and multivariate analyses
All patients who underwent spine surgery between 2012 and 2014 were identified by the Current Procedural Terminology (CPT) codes [
Four specific wound complications tracked by NSQIP were examined in this study: dehiscence, superficial SSI, deep SSI, and organ-space SSI. To construct a generalizable risk score, a composite binary outcome representing the occurrence of any wound complication was defined. Preoperative characteristics underwent univariate analysis for association with the composite wound complication outcome measure using Chi-square tests and Fischer's exact tests where appropriate. Variables were gated for entry into multivariate modeling using a P value threshold of P = 0.01. These factors were then submitted into a multivariate binary logistical regression model for association with the “any wound complication” composite outcome (entry level = 0.01, exit = 0.05). Statistical significance was determined by using an adjusted α from a Holm-Bonferroni correction. For each factor, odds ratios were calculated. Statistical analysis was performed with a combination of Statistical Analysis Software (SAS Institute Inc., Cary, NC) and Statistical Package for the Social Science (SPSS) software (version 24.0 IBM).
Risk score computation
Ten preoperative characteristics deemed statistically significant by multivariate analysis were used in generating weighted and unweighted risk scores. For the unweighted risk score, each independent risk factor was given a value of 1 when present. The factors were summed to create each individual patient's risk score, ranging from 0 to 10. A weighted risk score was created using adjusted multivariate odds ratios, consistent with previous risk score computations.[
In total, 99,152 spine surgery cases with complete datasets were analyzed [
Univariate analysis identified 33 characteristics significantly related to an increased risk of developing a postoperative wound complication [
In this study, we examined preoperative factors associated with postoperative wound complications following spine surgery. Using a sample encompassing nearly 100,000 cases from a national surgical database, we characterized wound complication rates and identified independent predictors associated with the development of at least one wound complication. Further, we implemented a novel scoring system for stratifying preoperative risk and demonstrated its performance among our sample. This study provides the largest to-date analysis of SSIs and dehiscence in spine surgery. Patient characteristics and wound complication rates [
Several of the characteristics have previously been reported as potential risk factors for SSI or dehiscence in specific spine surgeries. For example, a recent study of posterior cervical spine surgery identified BMI >35 kg/m2, chronic steroid use, prolonged operation time, hematocrit <33%, and ASA class >2 as independent risk factors for postoperative SSI.[
Our study is the first to identify risk factors for all wound complications including dehiscence and SSIs in patients undergoing spine surgery. For wound complications, specific factors such as inpatient status and emergent case classification are first reported here. Although some risk factors associated with dehiscence have been published previously in relation to other types of surgery, they have not been associated with wound complications specifically after spine surgery.[
Existing NSQIP-derived risk scores have shown promise in predicting outcomes within other surgical fields.[
Although NSQIP-based risk scores have been introduced within many different specialties,[
One notable advance of the present study is the rigorous vetting of preoperative data to exclude patients with incomplete datasets and missing variables. The handling of missing data in NSQIP-based studies has come under increased scrutiny and excluding patients with incomplete data entry is expected to address these concerns.[
Future work will be aimed at extending this risk score to include spine-specific variables and outcomes beyond 30 days for a more comprehensive scoring system. Additionally, further validation of this risk score is important by measuring the clinical response of providing preventative interventions for wound complications among identified “high-risk” patients in attempt to implement targeted cost-effective interventions. Such interventions include systemic antibiotics, local intraoperative antibiotics, multimodal preoperative skin preparation, negative pressure wound therapy, more extensive incisional closure (e.g. muscle flap closure), and more extensive postoperative wound care.[
This study introduces a novel preoperative risk score for the development of wound dehiscence and SSIs in patients undergoing spinal surgery. The results suggest that a subset of spine surgery patients account for a disproportionate percentage of adverse wound outcomes, suggesting that high-risk patients may be identified before surgery. Further development of this risk score may prove useful for identifying high-risk patients that might benefit from more intensive wound management.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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