Bobby D. Kim

Operative duration as an independent risk factor for postoperative complications in single-level lumbar fusion: an analysis of 4588 surgical cases.

Study Design. Multicenter retrospective cohort study. Objective. To estimate the impact of increasing surgical duration on outcomes after single-level lumbar fusion. Summary of Background Data. Lumbar fusion is a widely used practice for the treatment of disability and chronic low back pain. Longer operative duration is shown to correlate with increased morbidity and mortality in various surgical disciplines, but no large-scale study has been performed to validate this relationship in lumbar spine surgery. Methods. The American College of Surgeons National Surgical Quality Improvement Program was retrospectively reviewed to identify all patients who underwent lumbar fusion procedures during 2006 to 2011. Thirty-day morbidity and mortality rates were reported on the basis of operative time, whereas multivariate logistic regression model was used to examine operative duration as an independent risk factor for outcomes. Results. A total of 4588 patients were included in the analysis. The mean operative duration for all patients was 197 ± 105 minutes. Our multivariate risk-adjusted regression models demonstrated that increasing operative time was associated with step-wise increase in risk for overall complications (odds ratio [OR], 2.09–5.73), medical complications (OR, 2.18–6.21), surgical complications (OR, 1.65–2.90), superficial surgical site infection (OR, 2.65–3.97), and postoperative transfusions (OR, 3.25–12.19). Operative duration of 5 hours or more was also associated with increased risk of reoperation (OR, 2.17), organ/space surgical site infection (OR, 9.72), sepsis/septic shock (OR, 4.41), wound dehiscence (OR, 10.98), and deep vein thrombosis (OR, 17.22). Conclusion. Our data suggest that increasing operative duration is associated with a wide array of complications. Operative duration is, therefore, an important quality metric in the performance of lumbar fusion. Strategies to reduce operative time and further research to identify risk factors that are associated with longer surgical duration are needed for improved patient outcomes. Level of Evidence: 3

Predictors of unplanned readmission in patients undergoing lumbar decompression: multi-institutional analysis of 7016 patients.

OBJECT Unplanned hospital readmission represents a large financial burden on the Centers for Medicare and Medicaid Services, commercial insurance payers, hospitals, and individual patients, and is a principal target for cost reduction. A large-scale, multi-institutional study that evaluates risk factors for readmission has not been previously performed in patients undergoing lumbar decompression procedures. The goal of this multicenter retrospective study was to find preoperative, intraoperative, and postoperative predictive factors that result in unplanned readmission (UR) after lumbar decompression surgery. METHODS The National Surgical Quality Improvement Program (NSQIP) database was retrospectively reviewed to identify all patients who received lumbar decompression procedures in 2011. Risk-adjusted multivariate logistic regression analysis was performed to estimate independent predictors of UR. RESULTS The overall rate of UR among patients undergoing lumbar decompression was 4.4%. After multivariate logistic regression analysis, anemia (odds ratio [OR] 1.48), dependent functional status (OR 3.03), total operative duration (OR 1.003), and American Society of Anesthesiologists Physical Status Class 4 (OR 3.61) remained as independent predictors of UR. Postoperative complications that were significantly associated with UR included overall complications (OR 5.18), pulmonary embolism (OR 3.72), and unplanned reoperation (OR 56.91). CONCLUSIONS There were several risk factors for UR after lumbar spine decompression surgery. Identification of high-risk patients and appropriate allocation of resources to reduce postoperative incidence may reduce the readmission rate.

Predictors of thirty-day readmission after anterior cervical fusion.

Study Design. Retrospective cohort study. Objective. To determine the incidence of and factors predicting 30-day readmission after anterior cervical discectomy and fusion (ACDF). Summary of Background Data. ACDF is being performed on an increasing basis on a wider population of patients, which is accompanied by rising costs. Readmissions have the potential to further deplete health care resources. Although past studies have shown that readmissions after surgery are driven by operative complications, specific predictors of readmission after ACDF are not well researched. Methods. All patients who underwent ACDF or anterior corpectomy and fusion procedures in 2011 were selected from the American College of Surgeons National Quality Improvement database. Readmissions were analyzed on the basis of demographics, comorbidities, operative characteristics, and complications were compared in univariate analyses. Multivariate logistic regression models were created to isolate the independent effects of preoperative and postoperative factors on readmission. Results. The nationwide readmission rate after ACDF surgery in this study is 2.5%. Pulmonary complications (8.5%), wound complications (8.5%), and urinary tract infections (8.5%) are the most common complications seen in readmitted patients. Readmitted patients were significantly older (58 vs. 53, P = 0.003), with higher rates of diabetes and hypertension (28.8% vs. 13.9%, P = 0.001; 64.4% vs. 42.6%, P = 0.001, respectively). Although certain preoperative factors such as age 65 years or more and preoperative stay more than 24 hours increase the odds of operative complications (odds ratio, 3.5; 95% confidence interval, 2.0–6.0 and odds ratio, 6.2; 95% confidence interval, 3.4–11.1, respectively), hypertension may independently increase the likelihood of readmission outside of any effect on complications (odds ratio, 1.8; 95% confidence interval, 1.0–3.4). Conclusion. The data in this study suggests that surgeons are already controlling readmission rates by limiting peri- and postoperative complications, but patients with a history of hypertension could have an increased likelihood of being readmitted despite avoiding a complication. Level of Evidence: 3

Impact of resident involvement in neurosurgery: an analysis of 8748 patients from the 2011 American College of Surgeons National Surgical Quality Improvement Program database

OBJECT This study evaluates the impact of resident presence in the operating room on postoperative outcomes in neurosurgery. METHODS The authors retrospectively reviewed the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) and identified all cases treated in a neurosurgery service in 2011. Propensity scoring analysis and multiple logistic regression models were used to reduce patient bias and to assess independent effect of resident involvement. RESULTS Of the 8748 neurosurgery cases identified, residents were present in 4529 cases. Residents were more likely to be involved in complex procedures with longer operative duration. The multivariate analysis found that resident involvement was not a statistically significant factor for overall complications (OR 1.116, 95% CI 0.961-1.297), surgical complications (OR 1.132, 95% CI 0.825-1.554), medical complications (OR 1.146, 95% CI 0.979-1.343), reoperation (OR 1.250, 95% CI 0.984-1.589), mortality (OR 1.164, 95% CI 0.780-1.737), or unplanned readmission (OR 1.148, 95% CI 0.946-1.393). CONCLUSIONS In this multicenter study, the authors demonstrated that resident involvement in the operating room was not a significant factor for postoperative complications in neurosurgery service. This analysis also showed that much of the observed difference in postoperative complication rates was attributable to other confounding factors. This is a quality indicator for resident trainees and current medical education. Maintaining high standards in postgraduate training is imperative in enhancing patient care and reducing postoperative complications.

Risk Factors for Postoperative Infections Following Single Level Lumbar Fusion Surgery

Study Design. Retrospective multivariate analysis of a prospectively collected, multicenter database. Objective. To identify patient characteristics and perioperative risk factors associated with postoperative infectious complications after single-level lumbar fusion (SLLF) surgery. Summary of Background Data. Postoperative infection is a known complication after lumbar fusion. Risk factors for infectious complications after lumbar fusion have not been investigated using select set of SLLF procedures. Methods. Patients who underwent SLLF between 2006 and 2011 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. Multivariate logistic regression analyses were performed to identify pre- and intraoperative risk factors associated with postoperative infection. Results. A total of 3353 patients were analyzed in this study. Overall, 173 (5.2%) patients experienced a postoperative infection, including 86 (2.6%) surgical site infections (SSIs) and 111 (3.3%) non-SSI infectious complications (pneumonia, urinary tract infection, sepsis/septic shock). Twenty-four (0.7%) patients experienced both SSI and non-SSI infectious complications. Postoperative SSI were associated with obesity (odds ratio [OR], 1.628; 95% confidence interval [CI], 1.042–2.544), American Society of Anesthesiologists class more than 2 (OR, 2.078; 95% CI, 1.309–3.299), and operative time more than 6 hours (OR, 2.573; 95% CI, 1.310–5.056). Risk factors for non-SSI infectious complications included age (60–69 yr; OR, 3.279; 95% CI, 1.541–6.980; and ≥70 yr; OR, 3.348; 95% CI, 1.519–7.378), female sex (OR, 1.791; 95% CI, 1.183–2.711), creatinine more than 1.5 mg/dL (OR, 2.400; 95% CI, 1.138–5.062), American Society of Anesthesiologists class more than 2 (OR, 1.835; 95% CI, 1.177–2.860), and operative time more than 6 hours (OR, 3.563; 95% CI, 2.082–6.097). Conclusion. Across a wide study population, we identified that obesity, advanced American Society of Anesthesiologists classification, and longer operative time were predictive of postoperative SSI. We also demonstrated that increased age, female sex, serum creatinine more than 1.5 mg/dL, and prolonged operative duration are associated with non-SSI infectious complications after SLLF. Continued efforts to elucidate and optimize perioperative risk factors are warranted to improve outcomes in patients requiring spinal fusion. Level of Evidence: 3

Anesthesia duration as an independent risk factor for postoperative complications in free flap surgery: a review of 1,305 surgical cases.

Surgical dogma and objective data support the relationship between increased operative times and perioperative complications. However, there has been no large-scale, multi-institutional study that evaluates the impact of increased anesthesia duration on microvascular free tissue transfer. The National Surgical Quality Improvement Program (NSQIP) database was retrospectively reviewed to identify all free-flap patients between 2006 and 2011. Included patients were subdivided into quintiles of anesthesia time. Univariate and multivariate analyses were performed to assess its impact on 30-day postoperative complications. The mean anesthesia duration for all patients was 603 ± 222 minutes. In univariate analysis, 30-day overall/medical complications, reoperation, and free flap loss demonstrated statistically significant increases as anesthesia duration increased (p<0.05). However, in multivariate analyses, these trends and significances were abolished, with exception of the utilization of postoperative transfusions. Of interest, increasing anesthesia duration did not predict flap failure on multivariate analysis. We found that increased anesthesia time correlates with increased postoperative transfusions in free flap patients. As a result, limiting blood loss and avoiding prolonged anesthesia times should be goals for the microvascular surgeon. This is the largest multidisciplinary study to investigate the ongoing debate that longer anesthesia times impart greater risk.

Intraoperative transfusion of packed red blood cells in microvascular free tissue transfer patients: assessment of 30-day morbidity using the NSQIP dataset.

Although often a life-saving therapeutic maneuver, there is minimal data available that details the effects of intraoperative packed red blood cell transfusion (IOT) after microvascular free tissue transfer. The National Surgical Quality Improvement Program database was queried to identify all patients who underwent microvascular free tissue transfer between 2006 and 2010. Multivariate logistic regression models were used to determine the association between intraoperative transfusion and outcomes. Upon bivariate and multivariate analyses, IOT was significantly associated with higher rates of overall complications (odds ratio [OR], 2.02; 95% confidence interval [CI], 1.12-3.63), medical complications (OR, 3.35; 95% CI, 1.75-6.42), postoperative transfusion (OR, 6.02; 95% CI, 2.02-17.97), and reoperation (OR, 2.24; 95% CI, 1.24-4.04). IOT was not associated with either surgical complications or free flap loss. IOT significantly increases risk for adverse overall and medical complications. However, IOT was not associated with surgical complications or free flap loss. Transfusion practices in the operating room should be reevaluated to improve overall outcomes.

Spine surgeon specialty is not a risk factor for 30-day complication rates in single-level lumbar fusion: A Propensity score-matched study of 2528 patients

Study Design. Multicenter retrospective cohort study. Objective. To investigate the impact of spine surgeon specialty on 30-day complication rates in patients undergoing single-level lumbar fusion. Summary of Background Data. Operative care of the spine is delivered by surgeons who undergo either orthopedic or neurosurgical training. It is currently unknown whether surgeon specialty has an impact on 30-day complication rates in patients undergoing single-level lumbar fusion. Methods. The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively reviewed to identify all patients who underwent single-level lumbar fusion procedures during 2006–2011. Propensity score matching analysis was employed to reduce baseline differences in patient characteristics. Univariate and multivariate analyses were performed to assess the impact of spine surgeon specialty on 30-day complication rates. Results. A total of 2970 patients were included for analysis. After propensity matching, 1264 pairs of well-matched patients remained in the cohort. Overall complication rates in the unadjusted data set were 7.3% and 7.1% for the neurosurgery and orthopedic surgery cohort, respectively. Our multivariate analysis revealed that compared with the neurosurgery cohort, the orthopedic surgery cohort did not have statistically significant differences in odds ratios (OR) for development of any complication (OR, 0.95; 95% confidence interval [CI], 0.69–1.30; P = 0.740). Similarly, spine surgeon specialty was not a risk factor in any of the specific complications studied, including medical complications (OR, 1.11; 95% CI, 0.77–1.60; P = 0.583), surgical complications (OR, 0.76; 95% CI, 0.46–1.26; P = 0.287), or reoperation (OR, 1.10; 95% CI, 0.76–1.60; P = 0.618). Conclusion. Our analysis demonstrates that spine surgeon specialty is not a risk factor for any of the reported 30-day complications in patients undergoing single-level lumbar fusion. These data support the currently dichotomous paradigm of training for spine surgeons. Further research is warranted to validate this relationship in other spine procedures and for other outcomes. Level of Evidence: 4

Predictors of adverse events after parotidectomy: a review of 2919 cases.

Objective: There is a current paucity of large-scale, multi-institutional studies that explore the risk factors for major complications following parotidectomy. Methods: The American College of Surgeons National Surgical Quality Improvement Program participant use file was reviewed to identify all patients who had undergone parotidectomy between 2006 and 2011. Risk factors that predicted adverse events were estimated by using multivariate logistic regression. Results: Of 2919 included patients, 202 patients experienced adverse outcomes within the first 30 days of surgery. These included surgical complications in 76 (2.6%) patients; medical complications in 90 (3.1%) patients; death in 7 (0.2%) patients; and reoperation in 77 (2.6%) patients. Predictors of any complication included disseminated cancer (odds ratio [OR] = 2.28; 95% confidence interval [CI], 1.05-4.95; P = .036) and increasing total relative value units (OR = 1.01; 95% CI, 1.00-1.02; P = .027). Active smoking was a major risk factor for surgical complications (OR = 1.81; 95% CI, 1.08-3.05; P = .025). Dyspnea (OR = 2.93; 95% CI, 1.37-6.27; P = .006) significantly predicted medical complications. Conclusion: Although complication rates after parotidectomy are generally low, avoidance of specific and nonspecific postoperative complications still remains an area for improvement. Future outcomes databases should include procedure-specific complications, including facial nerve injury.

Preoperative Anemia Does Not Predict Complications After Single-level Lumbar Fusion: A Propensity Score–matched Multicenter Study

Study Design. Multicenter retrospective cohort study. Objective. To estimate the impact of preoperative anemia on 30-day complications in patients undergoing single-level lumbar fusion. Summary of Background Data. Anemia has been widely implicated as a risk factor in various surgical procedures including elective spine surgery. No large-scale study has been performed to examine this relationship in single-level lumbar fusion surgery. Methods. The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively reviewed to identify all patients who underwent single-level lumbar fusion procedures during 2006 to 2011. A propensity score–matching algorithm was used to match scores of anemic patients with that of nonanemic patients. Multivariate logistic regression analysis of unadjusted and propensity score–matched cohorts was performed to examine the effect of preoperative anemia on 30-day postoperative complication rates and length of hospital stay. Results. A total of 2960 patients met inclusion criteria. The propensity score–matching procedure yielded scores of 491 pairs of well-matched nonanemic and anemic patients. The multivariate analysis of propensity score–matched population found preoperative anemia to carry no significant association with any of the complications analyzed, including overall complications, medical complications, surgical complications, reoperation, mortality, or length of total hospital stay. Conclusion. For patients undergoing single-level lumbar fusion, preoperative anemia is not independently associated with increased risk of 30-day complications or increased length of stay. Further studies are needed to independently validate this relationship in other spine surgical procedures. Level of Evidence: 3