Nathan J. Lee

Frailty Index Is a Significant Predictor of Complications and Mortality After Surgery for Adult Spinal Deformity

Study Design. Retrospective study of prospectively collected data. Objective. To determine if the modified Frailty Index (mFI) could be used to predict postoperative complications in patients undergoing surgery for adult spinal deformity (ASD). Summary of Background Data. Surgery for patients with ASD is associated with high complication rates and significant concerns present during risk stratification with older patients. The mFI is an evaluation tool to describe the frailness of an individual and how their preoperative status may impact postoperative survival and outcomes. Using a large nationwide database, we assessed the utility of this instrument in patients undergoing surgery for ASD. Methods. The American College of Surgeons National Surgical Quality Improvement Program is a large multicenter clinical registry that prospectively collects preoperative variables, patient demographics, operative factors, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent fusion for spinal deformity. The previously described mFI was calculated based on the number of positive factors and univariate and multivariate logistic regression analysis were used to analyze the risk factors associated with mortality. Results. Overall, 1001 patients were identified and the mean mFI score was 0.09 (range: 0–0.545). Increasing mFI score was associated with higher complication, reoperation, and mortality rates (P < 0.05). mFI of 0.09 and 0.18 was an independent predictor of any complication, mortality, requiring a blood transfusion, pulmonary embolism/deep vein thrombosis, and reoperation (all P < 0.05). In comparison with age >60 years obesity class III, mFI was a superior predictor of several postoperative complications and reoperation. Conclusion. Frailty was an independent predictor of postoperative complications, mortality, and reoperation in patients undergoing surgery for ASD. Preoperative assessment of the mFI in this patient population can be utilized to improve current risk models. Level of Evidence: 3

Relationship Between ASA Scores and 30-Day Readmissions in Patients Undergoing Anterior Cervical Discectomy and Fusion.

Study Design. Retrospective study of prospectively collected data. Objective. To assess the American Society of Anesthesiologists (ASA)score as an independent predictor of 30-readmissions after anterior cervical discectomy and fusion (ACDF). Summary of Background Data. The ASA classification scheme was introduced in 1941 to establish a scoring system to evaluate the overall health status and comorbidities of patients before surgery10–12. Although the score was designed to predict postoperative complications, it may also be used as a predictor of perioperative risk. Methods. Data collected for the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database in the period 2005 to 2012 were used in the present analysis. Current Procedural Terminology codes were used to identify elective ACDF cases (CPT codes: 22551, 22554, and 63075). The primary study outcome was 30-day readmission rates after elective ACDF in adults. Univariate and multivariate analysis was used to determine whether any of age, sex, race, body mass index, comorbidities, operative variables, or ASA class were predictors of 30-day readmission rates after ACDF. Results. From the ACS-NSQIP database, 1701 elective ACDF cases were included for analysis, including 92 (5.5%) ASA class 1,955 (56.1%) ASA class 2,618 (36.3%) ASA class 3 and 34 (2.0%) ASA class 4 patients. Using ASA class 1 as a reference, significant independent predictors included being in ASA class 4 [odds ratio (OR) 5.7; 95% confidence interval (CI) 0.58–56.7; P = 0.039], having cardiac comorbidities (OR 2.2; 95% CI 1.2–4.2; P = 0.017), and prior strokes (OR 3.8; 95% CI 1.4–10.1; P = 0.0086). Conclusion. In conclusion, the unplanned readmission rate for patients undergoing ACDF was 3.2%. There was a significant and independent association between a high ASA class (class 4), cardiac comorbidities and prior strokes with 30-day unplanned readmissions after ACDF. The ASA score may be a valuable tool for the preoperative assessment of ACDF patients for risk of unplanned readmissions. Level of Evidence: 3

Frailty Index as a Predictor of Adverse Postoperative Outcomes in Patients Undergoing Cervical Spinal Fusion.

Study Design. Retrospective study of prospectively collected data. Objective. To investigate the applicability of the modified frailty index (mFI) as a predictor of adverse postoperative events in patients undergoing anterior cervical discectomy and fusion (ACDF) or posterior cervical fusion (PCF). Summary of Background Data. Prior studies have investigated the mFI and shown it as an independent predictor of adverse postoperative outcomes across multiple surgical specialties. However, this topic has not still been studied in patients undergoing cervical fusion or in spinal surgery. Methods. The National Surgical Quality Improvement Program is a multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent elective ACDF and PCF between 2005 and 2012. The mFI was calculated for each patient. Univariate analysis and multivariate logistic regression were used to analyze the mFI as a predictor for postoperative complications. Results. For ACDF group, Clavien-Dindo grade IV complications rate increased from 0.8% to 9.0% as mFI increased from 0 to ≥0.27, and mFI = 0.27 was found to be an independent predictor of Clavien-Dindo grade IV complications (odds ratio, OR, = 4.67, 95% confidence interval, CI, = 2.27–9.62, P < 0.001). For PCF groups, Clavien-Dindo grade IV complications rate increased from 0.7% to 20.0% as mFI increased from 0 to ≥0.36, and mFI ≥ 0.36 was identified as an independent predictor of Clavien-Dindo grade IV complications (OR = 41.26, 95% CI = 6.62–257.15, P < 0.001). Conclusion. The mFI was shown to be an independent predictor of Clavien-Dindo grade IV complications in patients undergoing ACDF or PCF. The mFI itself may be used to stratify risks in patients undergoing cervical fusion, or, the mFI scheme could be used as a platform upon which more efficient risk stratification could be done with addition of other variables. Level of Evidence: 4

Frailty is associated with morbidity in adults undergoing elective anterior lumbar interbody fusion (ALIF) surgery

BACKGROUND CONTEXT Prior studies have suggested no significant differences in functional status and postoperative complications of elderly versus nonelderly patients undergoing posterior lumbar interbody fusion; however, similar studies have not been comprehensively investigated in the setting of anterior lumbar interbody fusion (ALIF). PURPOSE The objective was to quantify the ability of the modified Frailty Index (mFI) to predict postoperative events in patients undergoing ALIF. STUDY DESIGN Secondary analysis of prospectively collected data. PATIENT SAMPLE Patients undergoing ALIF in the National Surgical Quality Improvement Program (NSQIP) participant files for the period 2010 through 2014. OUTCOMES MEASURES Outcome measures included any postoperative complication, return to operating room (OR), and length of stay >5 days. METHODS NSQIP participant files from 2010 to 2014 were used to identify patients undergoing ALIF. The mFI used in the present study is an 11-variable assessment that maps 16 NSQIP variables to 11 variables in the Canadian Study of Health and Ageing Frailty Index. Univariate analysis and multivariable logistic regression models were used to compare the relative strength of association between mFI with outcome variables of interest. RESULTS In total, 3,920 ALIF cases were identified and grouped according to their mFI score: 0 (n=2,025), 0.09 (n=1,382), 0.18 (n=464), or ≥0.27 (n=49). As the mFI increased from 0 (no frailty-associated variables) to 0.27 (4 of 11) or higher, there was a significant stepwise increase in any complication from 10.8% to 32.7%. After multivariable regression analysis, no significant association was found between higher mFI scores with urinary tract infections and venous thromboembolism. High frailty scores were significant predictors of any complication (mFI of ≥0.27 [reference: 0]; OR 2.4; p=.040) and pulmonary complications (mFI score ≥0.27; OR 7.5; p=.001). CONCLUSIONS In summary, high mFI scores were found to be independently associated with any complication and pulmonary complications in patients who underwent ALIF. The use of mFI together with traditional risk factors may help better identify high-surgical risk patients, which may be useful for preoperative and postoperative care optimization.

Impact of Obesity on Outcomes in Adults Undergoing Elective Posterior Cervical Fusion

Study Design. Retrospective study of prospectively collected data. Objective. To determine the effect of obesity (body mass Index > 30) on postoperative morbidity and mortality after elective posterior cervical fusion in adults. Summary of Background Data. In those with spine disease, obesity has been shown to portend poorer general and disease-specific functional health status. The effect of obesity on outcomes after spine surgery, especially posterior cervical fusion, however, remains unclear. Previous studies have been contradictory to one another and largely limited by small sample sizes. Methods. The American College of Surgeons National Surgical Quality Improvement Program is a large multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent posterior cervical fusion between 2005 and 2012. Patients were separated into cohorts based on obesity status. Univariate analysis and multivariate logistic regression were used to analyze the effect of obesity on postoperative morbidity and mortality. Results. There was a significantly higher rate of only venous thromboembolism (VTE) in the obese group compared with nonobese cohort (3.5% vs. 0.6%, P = 0.015). On multivariate analysis, obesity was found to be an independent predictor (odds ratio 6.15; 95% confidence interval [CI], 1.26–30.20; P = 0.02) for VTE. Conclusion. The present study demonstrated that patients with obesity can safely undergo posterior cervical fusion surgery. Although obesity predisposed to an elevated risk of VTE, postoperative mortality and morbidity were otherwise not significantly increased in this population. Level of Evidence: 3

Impact of Gender on 30-Day Complications After Adult Spinal Deformity Surgery.

Study Design. Retrospective study of prospectively collected data. Objective. To determine if postoperative morbidity for patients undergoing spinal deformity surgery varies by sex. Summary of Background Data. Influence of sex has been investigated in other surgical procedures but has not yet been studied in adult spinal deformity surgery. Methods. The American College of Surgeons National Surgical Quality Improvement Program is a large multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent fusion for spinal deformity. Patients were separated into groups of male and female sex. Univariate analysis and multivariate logistic regression were used to analyze the effect of sex on the incidence of postoperative morbidity and mortality. Results. Female sex was found to be a predictor of any complication[odds ratio (OR): 1.4, 95% confidence interval (CI) 1.2–1.7, P < 0.0001], intra- or postoperative RBC transfusion (OR: 1.6, 95% CI 1.4–1.9, P < .0001), urinary tract infection (OR: 2.0, 95% CI 1.2–3.3, P = 0.0046), and length of stay >5 days (OR: 1.3, 95% CI 1.1–1.5, P = 0.0015). Male sex was associated with higher rate of pulmonary (2.9% vs. 2.0%, P = 0.0344) and cardiac complications (0.9% vs. 0.5%, P = 0.0497). However, male sex as an independent risk factor for pulmonary (OR: 1.4, 95% CI 1.0–2.1, P = 0.0715) and cardiac complications (OR: 1.9, 95% CI 0.9–4.0, P = 0.1076) did not reach significance. Conclusion. Female sex was found to increase overall morbidity, particularly for urinary tract infection, transfusion, and length of stay >5 days. Male sex was associated with greater incidence of pulmonary and cardiac complications. Thus, sex and other patient characteristics highlighted must be considered as part of surgical risk planning and patient counseling. Level of Evidence: 3

Analysis of Risk Factors for Major Complications Following Elective Posterior Lumbar Fusion

Study Design. Retrospective study of prospectively collected data. Objective. To identify risk factors for the development of any major complication after elective posterior lumbar fusion (PLF). Summary of Background Data. PLF is one of the most performed fusion techniques with utilization rates increasing by 356% between 1993 and 2001. Surgical and anesthetic advances have made the option of surgery more accessible for elderly patients with a larger comorbidity burden. Identifying risk factors for the development of major complications after elective PLF is important for patient risk stratification and patient safety efforts. Methods. The 2011 to 2014 American College of Surgeons National Surgical Quality Improvement Program database was queried using Current Procedural Terminology codes 22612, 22630, and 22633. Patients were divided into two cohorts based on the development of any major complication. Bivariate and multivariate logistic regression analyses were employed to identify predictors for the development of ≥ 1, ≥ 2, and ≥ 3 major complications. Results. A total of 7761 patients met the inclusion criteria for the study of which, 2055 (26.5%) patients developed one major complication, 249 (3.2%) patients developed two major complications, and 151 (1.9%) patients developed three major complications. The most common complication was intra/postoperative red blood cell transfusion (23.2%). Three multivariate logistic regression models were employed to identify factors associated with ≥ 1, ≥ 2, and ≥ 3 major complications. Patient variables present across all three models were osteotomy, pelvic fixation, operation time ≥4 hours, bleeding disorder, and American Society of Anesthesiology Class ≥ 3. Conclusion. Several risk factors were identified for the development of major complications after elective PLF. Identification of these factors can improve the selection of appropriate surgical candidates, patient risk stratification, and patient postoperative safety. Level of Evidence: 3

Impact of Insulin Dependence on Perioperative Outcomes Following Anterior Cervical Discectomy and Fusion.

Study Design. A retrospective analysis of prospectively collected data. Objective. Our objective was to analyze insulin-dependent and noninsulin-dependent diabetes mellitus (IDDM and NIDDM) as potential risk factors for complications, reoperations, and readmissions within 30 days following anterior cervical discectomy and fusion (ACDF). Summary of Background Data. ACDF is a common surgical procedure with growing utilization and good long-term outcomes. Readmissions and reoperations are associated with increased morbidity and inferior long-term outcomes. IDDM and NIDDM are often associated with increased complication rates. Methods. This was a retrospective analysis of prospectively collected data from the ACS NSQIP database. Patients ≥18 years old undergoing ACDF from 2005 to 2012 were included. Readmission, perioperative events, and reoperation within 30 days following ACDF were measured. Patient demographics, perioperative data, preoperative labs, and postoperative events were assessed. Patients with NIDDM or IDDM were compared with nondiabetic patients using multivariate logistic regression analysis with significance defined as P < 0.05. Odds ratio (OR) was calculated with a 95% confidence interval (CI). Results. Three thousand seven hundred twenty-six patients were included of whom 270 were NIDDM and 171 IDDM. Readmissions and reoperation data were available only from 2011 to 2012, including 1423 nondiabetes mellitus (non-DM), 193 NIDDM, and 87 IDDM cases. NIDDM was associated with higher rates of urinary tract infection (UTI) (P < 0.007), and return to operating room (P = 0.012) than nondiabetic patients. IDDM was associated with higher rates of reoperations (P = 0.04), readmissions (P < 0.0001), and total length of stay (LOS) >5 days (P < 0.0001). Following adjusted multivariate analysis, only IDDM status remained an independent predictor for 30-day readmission (OR 4.8, 95% CI 2.3–10.1). Conclusion. Patients with NIDDM and IDDM were at an increased risk for several postoperative complications following ACDF. IDDM was independently associated with increased 30-day readmission rates. Diabetic patients should be counseled appropriately, and the importance of close perioperative care is highlighted in this study. Level of Evidence: 3

Hospital Acquired Conditions (HACs) in Adult Spinal Deformity Surgery: Predictors for HACs and Other 30-day Postoperative Outcomes.

Study Design. A retrospective study of prospectively collected data. Objective. The aim of this study was to identify risk factors in developing hospital-acquired conditions (HACs) and association of HACs with other 30-day complications in the adult spinal deformity (ASD) population. Summary of Background Data. HACs are subject to a nonpayment policy by the Center for Medicare and Medicaid Services and provide an incentive for medical institutions to improve patient safety. HACs in the ASD population may further exacerbate the already high rates of postoperative morbidity and mortality. Methods. The 2010 to 2014 ACS-NSQIP database was queried using Current Procedural Terminology (CPT) codes for adults who had fusion for spinal deformity. Patients were divided into two cohorts on the basis of the development of an HAC, as defined as a case of surgical site infection, urinary tract infection, or venous thromboembolism. Univariate and multivariate logistic regression analyses were employed to determine predictors for HACs and association of HACs with other 30-day postoperative outcomes. Results. Five thousand eight hundred nineteen patients met the inclusion criteria for the study of whom 313 (5.4%) had an HAC. Multivariate logistic regression analysis revealed that age 61 to 70 versus ⩽50 years [odds ratio (OR) = 1.58, 1.10–2.27, P = 0.013], 71 to 80 versus ⩽50 years (OR = 1.94, 1.31–2.87, P = 0.001), and >80 versus ⩽50 years (OR = 2.30, 1.21–4.37, P = 0.011), dependent/partially dependent versus independent functional status (OR = 1.74, 1.13–2.68, P = 0.011), combined versus anterior surgical approach (OR = 2.46, 1.43–4.24, P = 0.001), and posterior versus anterior surgical approach (OR = 1.64, 1.19–2.25, P = 0.002), osteotomies (OR = 1.61, 1.22–2.13, P = 0.001), steroid use (OR = 2.19, 1.39–3.45, P = 0.001), obesity (OR = 1.38, 1.09–1.74, P = 0.007), and operation time ≥4 hours (OR = 2.42, 1.82–3.21, P < 0.001) were predictive factors in developing an HAC. Conclusion. Several modifiable and nonmodifiable factors (age, functional status, surgical approach, utilization of osteotomies, steroid use, obesity, and operation time ≥4 hours) were associated with developing an HAC. HACs were also risk factors for other postoperative complications. Level of Evidence: 3

Pediatric Cervical Spine and Spinal Cord Injury: A National Database Study

Study Design. A retrospective administrative database analysis. Objective. The aim of this study was to investigate the incidence and characteristics of pediatric cervical spine injury (PCSI) utilizing the Kids’ Inpatient Database (KID). Summary of Background Data. PCSI is debilitating, but comprehensive analyses have been difficult due to its rarity. There have been a few database studies on PCSI; however, the studies employed databases that suffer from selection bias. Methods. The triennial KID was queried from years 2000 to 2012 using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Pediatric admissions were divided into five age groups reflecting different developmental stages. PCSI was analyzed in terms of trend, demographics, injury characteristics, hospital characteristics, comorbidities, and outcomes variables. Multivariate logistic regression analyses were used to identify independent risk factors for PCSI among trauma admissions and to identify independent risk factors for mortality among PCSI admissions. Results. Over the past decade, the overall prevalence of traumatic PCSI was 2.07%, and the mortality rate was 4.87%. Most frequent cause of PCSI was transportation accidents, accounting for 57.51%. Upper cervical spine injury (C1–C4), cervical fracture with spinal cord injury, spinal cord injury without radiographic abnormality (SCIWORA), and dislocation showed a decreasing trend with age. Some comorbidities, including, but not limited to, fluid and electrolyte disorders, and paralysis were common across all age groups, while substance abuse showed a bimodal distribution. Independent risk factors for PCSI after trauma were older cohorts, non-Northeast region, and transportation accidents. For mortality after PCSI, independent risk factors were younger cohorts, transportation accidents, upper cervical spine injury, dislocation, and spinal cord injuries. Median length of stay and cost were 3.84 days and