Nathaniel T. Ondeck

Discriminative ability of commonly used indices to predict adverse outcomes after poster lumbar fusion: a comparison of demographics, ASA, the modified Charlson Comorbidity Index, and the modified Frailty Index

BACKGROUND CONTEXT As research tools, the American Society of Anesthesiologists (ASA) physical status classification system, the modified Charlson Comorbidity Index (mCCI), and the modified Frailty Index (mFI) have been associated with complications following spine procedures. However, with respect to clinical use for various adverse outcomes, no known study has compared the predictive performance of these indices specifically following posterior lumbar fusion (PLF). PURPOSE This study aimed to compare the discriminative ability of ASA, mCCI, and mFI, as well as demographic factors including age, body mass index, and gender for perioperative adverse outcomes following PLF. STUDY DESIGN/SETTING A retrospective review of prospectively collected data was performed. PATIENT SAMPLE Patients undergoing elective PLF with or without interbody fusion were extracted from the 2011-2014 American College of Surgeons National Surgical Quality Improvement Program (NSQIP). OUTCOME MEASURES Perioperative adverse outcome variables assessed included the occurrence of minor adverse events, severe adverse events, infectious adverse events, any adverse event, extended length of hospital stay, and discharge to higher-level care. METHODS Patient comorbidity indices and characteristics were delineated and assessed for discriminative ability in predicting perioperative adverse outcomes using an area under the curve analysis from the receiver operating characteristics curves. RESULTS In total, 16,495 patients were identified who met the inclusion criteria. The most predictive comorbidity index was ASA and demographic factor was age. Of these two factors, age had the larger discriminative ability for three out of the six adverse outcomes and ASA was the most predictive for one out of six adverse outcomes. A combination of the most predictive demographic factor and comorbidity index resulted in improvements in discriminative ability over the individual components for five of the six outcome variables. CONCLUSION For PLF, easily obtained patient ASA and age have overall similar or better discriminative abilities for perioperative adverse outcomes than numerically tabulated indices that have multiple inputs and are harder to implement in clinical practice.

Differences in Short-term Outcomes Between Primary and Revision Anterior Cervical Discectomy and Fusion.

STUDY DESIGN Retrospective cohort study. OBJECTIVE To compare short-term morbidity for primary and revision anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA Revision ACDF procedures are relatively common, yet their risks are poorly characterized in the literature. There is a need to assess the relative risk of revision ACDF procedures compared with primary surgery. METHODS The prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent primary and revision ACDF from 2005 to 2014. The occurrence of 30-day postoperative complications, readmission, operative time, and postoperative length of stay were compared between primary and revision procedures using multivariate regression to control for patient and operative characteristics. RESULTS A total of 20,383 ACDF procedures were identified, 1219 (6.0%) of which were revision cases. On multivariate analysis, revision procedures were associated with significantly increased risk of any adverse event (relative risk [RR] 2.3, P < 0.001), any severe adverse event (RR 2.2, P < 0.001), thromboembolic events (RR 3.3, P = 0.001), surgical site infections (RR 3.2, P < 0.001), return to the operating room (RR 1.9, P = 0.001), any minor adverse event (RR 2.5, P < 0.001), and blood transfusion (RR 8.3, P < 0.001). Revision procedures had significantly increased risk of readmission within 30 days (RR = 1.6, P = 0.001). Minor, but statistically significant increases in average operative time and postoperative length of stay were identified for revisions procedures (7 min and half a day, respectively [P < 0.001 for both]). CONCLUSION Revision procedures were associated with significantly increased risk of multiple adverse outcomes, including thromboembolic events, surgical site infections, return to the operating room, blood transfusion, and readmission within 30 days. These results are important for patient counseling and risk stratification. LEVEL OF EVIDENCE 3.STUDY DESIGN Retrospective cohort study. OBJECTIVE To compare short-term morbidity for primary and revision anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA Revision ACDF procedures are relatively common, yet their risks are poorly characterized in the literature. There is a need to assess the relative risk of revision ACDF procedures compared to primary surgery. METHODS The prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients that underwent primary and revision ACDF from 2005 to 2014. The occurrence of 30-day postoperative complications, readmission, operative time, and postoperative length of stay were compared between primary and revision procedures using multivariate regression to control for patient and operative characteristics. RESULTS A total of 20,383 ACDF procedures were identified, 1,219 (6.0%) of which were revision cases. On multivariate analysis, revision procedures were associated with significantly increased risk of any adverse event (RR 2.3, p < 0.001), any severe adverse event (RR 2.2, p < 0.001), thromboembolic events (RR 3.3, p = 0.001), surgical site infections (RR 3.2, p < 0.001), return to the operating room (RR 1.9, p = 0.001), any minor adverse event (RR 2.5, p < 0.001), and blood transfusion (RR 8.3, p < 0.001). Revision procedures had significantly increased risk of readmission within 30 days (RR = 1.6, p = 0.001). Minor, but statistically significant increases in average operative time and postoperative length of stay were identified for revisions procedures (7 minutes and half a day, respectively [p < 0.001 for both]). CONCLUSIONS Revision procedures were associated with significantly increased risk of multiple adverse outcomes, including thromboembolic events, surgical site infections, return to the operating room, blood transfusion, and readmission within 30 days. These results are important for patient counseling and risk-stratification. LEVEL OF EVIDENCE 3.

What Is the Timing of General Health Adverse Events That Occur After Total Joint Arthroplasty

BackgroundDespite extensive research regarding risk factors for adverse events after total joint arthroplasty (TJA), there are few publications describing the timing at which such adverse events occur.Questions/purposes(1) On which postoperative day do certain adverse events occur? (2) What adverse events occur earlier after TKA than after THA? (3) For each adverse event, what proportion occurred after hospital discharge?MethodsWe screened the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) to identify all patients undergoing primary THA and primary TKA between 2005 and 2013, resulting in a study population of 124,657 patients evaluated as part of this retrospective database analysis. For each of eight different adverse events, the median postoperative day of diagnosis, interquartile range for day of diagnosis, and middle 80% for day of diagnosis were determined. Multivariate Cox proportional hazards modeling was used to test whether there is a difference of timing for each adverse event as stratified by TKA or THA. The proportion of adverse events occurring after versus before discharge was also calculated.ResultsThe median day of diagnosis (and interquartile range; middle 80%) for stroke was 2 (1–10; 1–19), myocardial infarction 3 (2–6; 1–15), pulmonary embolism 3 (2–7; 1–19), pneumonia 4 (2–9; 2–17), deep vein thrombosis 6 (3–14; 2–23), urinary tract infection 8 (3–16; 2–24), sepsis 10 (5–19; 2–24), and surgical site infection 17 (11–23; 6–28). For the later occurring adverse events (surgical site infection, sepsis), the rate of occurrence remained high at the end of the 30-day postoperative period. Timing was earlier in patients undergoing TKA for pulmonary embolism (day 3 [interquartile range 2–6] versus 5 [3–17], p < 0.001) and deep vein thrombosis (day 5 [2–11] versus 13 [6–22], p < 0.001). The proportion of events occurring after discharge for myocardial infarction was 97 of 283 (34%), stroke 42 of 118 (36%), pulmonary embolism 223 of 625 (36%), pneumonia 171 of 426 (40%), deep vein thrombosis 576 of 956 (60%), urinary tract infection 958 of 1406 (68%), sepsis 284 of 416 (68%), and surgical site infection 1147 of 1212 (95%).ConclusionsAs lengths of hospital stay after TJA continue to decrease, our findings suggest that caution is in order because several acute and immediately life-threatening findings, including myocardial infarction and pulmonary embolism, might occur after discharge. Furthermore, the timing of surgical site infection and sepsis suggests that even the 30-day followup afforded by the ACS-NSQIP may not be sufficient to study the latest occurring adverse events. Additionally, both pulmonary embolism and deep vein thrombosis tend to occur earlier after TKA than THA, and this should guide clinical surveillance efforts in patients undergoing those procedures. These findings also indicate that inpatient-only databases (such as the Nationwide Inpatient Sample) may fail to capture a very large proportion of postoperative adverse events, weakening the conclusions of many published studies using those databases.Level of EvidenceLevel III, therapeutic study.

Demographics, Mechanisms of Injury, and Concurrent Injuries Associated With Calcaneus Fractures: A Study of 14 516 Patients in the American College of Surgeons National Trauma Data Bank.

Background. This study uses the American College of Surgeons National Trauma Data Bank (NTDB) to update the field on the demographics, injury mechanisms, and concurrent injuries among a national sample of patients admitted to the hospital department with calcaneus fractures. Methods. Patients with calcaneus fractures in the NTDB during 2011-2012 were identified and assessed. Results. A total of 14 516 patients with calcaneus fractures were included. The most common comorbidity was hypertension (18%), and more than 90% of fractures occurred via traffic accident (49%) or fall (43%). A total of 11 137 patients had concurrent injuries. Associated lower extremity fractures had the highest incidence and occurred in 61% of patients (of which the most common were other foot and ankle fractures). Concurrent spine fractures occurred in 23% of patients (of which the most common were lumbar spine fractures). Concurrent nonorthopaedic injuries included head injuries in 18% of patients and thoracic organ injuries in 15% of patients. Conclusion. This national sample indicates that associated injuries occur in more than three quarters calcaneus fracture patients. The most common associated fractures are in close proximity to the calcaneus. Although the well-defined association of calcaneus fractures with lumbar spine fractures was identified, the data presented highlight additional strong associations of calcaneus fractures with other orthopaedic and nonorthopaedic injuries. Levels of Evidence: Prognostic, Level III: Retrospective review of a prospectively collected cohort

Revision Total Knee Arthroplasty in Octogenarians: An Analysis of 957 Cases

BACKGROUND The number of octogenarians undergoing revision total knee arthroplasty (TKA) is increasing. However, there has been a lack of studies investigating the perioperative course and safety of revision TKA performed in this potentially vulnerable population in a large patient population. The purpose of this study is to compare complications following revision TKA between octogenarians and 2 younger patient populations (<70 and 70-79 year olds). METHODS Patients who underwent revision TKA were identified in the 2005-2015 National Surgical Quality Improvement Program database and stratified into 3 age groups: <70, 70-79, and ≥80 years. Baseline preoperative and intraoperative characteristics were compared between the 3 groups. Propensity score matched comparisons were then performed for 30-day perioperative complications, length of hospital stay, and readmissions. RESULTS This study included 6523 (<70 years), 2509 (70-79 years), and 957 octogenarian patients who underwent revision TKA. After propensity matching, statistical analysis revealed only higher rates of blood transfusion and slightly longer length of stay in octogenarians compared to <70 year olds. Similarly, octogenarians had only higher rates of blood transfusion and slightly longer length of stay compared to 70-79 year olds. Notably, there were no differences in mortality or readmission between octogenarians compared to younger populations. CONCLUSION These data suggest that revision TKA can safely be considered for octogenarians with the observation of higher rates of blood transfusion and slightly longer length of stay compared to younger populations. Octogenarian patients need not be discouraged from revision TKA solely based on their advanced age.

Of 20,376 Lumbar Discectomies, 2.6% of Patients Readmitted within 30 Days: Surgical Site Infection, Pain, and Thromboembolic Events are the Most Common Reasons for Readmission.

Study Design. A retrospective cohort study of prospectively collected data. Objective. As an initial effort to address readmissions after lumbar discectomy, reasons for hospital readmission are identified and discussed. Summary of Background Data. Lumbar discectomy is a commonly performed procedure. The Affordable Care Act codifies penalties for hospital readmissions. New quality-based reimbursements tied to readmissions call for a better understanding of the causes of readmission after procedures such as lumbar discectomy. Methods. Lumbar discectomies performed in 2012 to 2014 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Patient demographics, surgical variables, and reasons for readmissions within 30 days were recorded. Pearson chi square was used to compare rates of demographics and surgical variables between readmitted and nonreadmitted patients. Multivariate regression was used to identify risk factors for readmission. Results. Of 20,376 lumbar discectomies, 533 patients (2.62%) were readmitted within 30 days of surgery. The most common reasons for readmission were surgical site infections (n = 130, 0.64% of all discectomies, 24.4% of all readmissions), followed by pain issues (n = 89, 0.44%, 16.7%), and thromboembolic events (43, 0.21%, 8.1%). Overall time to readmission was 13.0 ± 8.0 days (mean ± standard deviation). Factors most associated with readmission after lumbar discectomy were higher American Society of Anesthesiologists class (relative risk = 1.49, P < 0.001) and prolonged operative time (relative risk = 1.41, P = 0.002). Conclusion. Surgical site infection, postoperative pain, and thromboembolic events were the most common reasons for readmission after lumbar discectomy. These findings identify potential areas for quality improvement initiatives. Level of Evidence: 3

Tibial shaft fracture: A large-scale study defining the injured population and associated injuries

This is the first large-scale study to define the injured population and examine associated injuries for patients with tibial shaft fractures. Patients over 18 years of age in the National Trauma Data Bank (NTDB) who presented with tibial shaft fractures during 2011 and 2012 were identified. Modified Charlson Comorbidity Index (CCI), mechanism of injury (MOI), injury severity score (ISS), and specific associated injuries were described. Multivariate logistic regression was used to identify predictors of mortality.

Evaluating the effect of growing patient numbers and changing data elements in the National Surgical Quality Improvement Program (NSQIP) database over the years: a study of posterior lumbar fusion outcomes

BACKGROUND CONTEXT The use of national databases in spinal surgery outcomes research is increasing. A number of variables collected by the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) changed between 2010 and 2011, coinciding with a rapid increase in the number of patients included per year. However, there has been limited study evaluating the effect that these changes may have on the results of outcomes studies. PURPOSE The present study aimed to investigate the influence of changing data elements and growth of the NSQIP database on results of lumbar fusion outcomes studies. STUDY DESIGN/SETTING This is a retrospective cohort study of prospectively collected data. PATIENT SAMPLE The NSQIP database was retrospectively queried to identify 19,755 patients who underwent elective posterior lumbar fusion surgery with or without interbody fusion between 2005 and 2014. Patients were split into two groups based on year of surgery: 2,802 from 2005 to 2010 and 16,953 from 2011 to 2014. OUTCOME MEASURES The occurrence of adverse events after discharge from the hospital, within postoperative day 30, was determined. METHODS Preoperative characteristics and 30-day perioperative outcomes were compared between the era groups using bivariate analysis. To illustrate the effect of such changing data elements, the association between age and postoperative outcomes in the era groups was analyzed using multivariate Poisson regression. The present study had no funding sources, and there were no study-related conflicts of interest for any authors. RESULTS There were significant differences between the era groups for a variety of preoperative characteristics. Postoperative events such blood transfusion and deep vein thrombosis were also significantly different between the era groups. For the 2005-2010 cohort, age was significantly associated with septic shock by multivariate analysis. For the 2011-2014 cohort, age was significantly associated with septic shock, urinary tract infection, blood transfusion, myocardial infarction, and extended length of stay. CONCLUSIONS The NSQIP database has undergone substantial changes between 2005 and 2014. These changes may contribute to different results in analyses, such as the association between age and postoperative outcomes, when using older versus newer data. Conclusions from early studies using this database may warrant reconsideration.

Dialysis is an independent risk factor for perioperative adverse events, readmission, reoperation, and mortality for patients undergoing elective spine surgery

BACKGROUND CONTEXT The prevalence of dialysis-dependent patients in the United States is growing. Prior studies evaluating the risk of perioperative adverse events for dialysis-dependent patients are either institutional cohort studies limited by patient numbers or administrative database studies limited to inpatient data. PURPOSE The present study uses a large, national sample with 30-day follow-up to investigate dialysis as risk factor for perioperative complications independent of patient demographics or comorbidities. STUDY DESIGN/SETTING This is a retrospective cohort study. PATIENT SAMPLE Patients undergoing elective spine surgery with or without dialysis from the 2005-2015 National Surgical Quality Improvement Program (NSQIP) database were included in the study. OUTCOME MEASURES Postoperative complications within 30 days and binomial reoperation, readmission, and mortality within 30 days were determined. METHODS The 2005-2015 NSQIP databases were queried for adult dialysis-dependent and dialysis-independent patients undergoing elective spinal surgery. Differences in 30-day outcomes were compared using risk-adjusted multivariate regression and coarsened exact matching analysis for adverse events, unplanned readmission, reoperation, and mortality. The percentage of complications occurring before versus after hospital discharge was also assessed. The authors have no financial disclosures related to the present study. RESULTS A total of 467 dialysis and 173,311 non-dialysis patients met the inclusion criteria. Controlling for age, gender, body mass index, functional status, and American Society of Anesthesiologists (ASA) class, dialysis patients were found to be at significantly greater odds of any adverse event (odds ratio [OR]=2.52 before, 2.17 after matching, p=<.001), major adverse event (OR=2.90 before, 2.52 after matching, p=<.001), and minor adverse event (OR=1.50 before matching, p=<.025, but not significantly different after matching). Further, dialysis patients were significantly more likely to return to the operating room (OR=2.77 before, 2.50 after matching, p=<.001), have unplanned readmissions (OR=2.73 before, 2.37 after matching, p=<.001), and die within 30 days (OR=3.77 before, 2.71 after matching, p=<.001). Adverse events occurred after discharge for 51.78% of non-dialysis patients and for 43.80% of dialysis patients. CONCLUSIONS Dialysis patients undergoing elective spine surgery are at significantly higher risk of aggregated adverse outcomes, return to the operating room, readmission, and death than non-dialysis patients, even after controlling for patient demographics and overall health (as indicated by ASA class). These differences need to be considered when determining treatment options. Additionally, with bundled payments expected in spine surgery, physicians and hospitals need to account for increased costs and liabilities when working with dialysis patients.

Missing data treatments matter: an analysis of multiple imputation for anterior cervical discectomy and fusion procedures

BACKGROUND CONTEXT The presence of missing data is a limitation of large datasets, including the National Surgical Quality Improvement Program (NSQIP). In addressing this issue, most studies use complete case analysis, which excludes cases with missing data, thus potentially introducing selection bias. Multiple imputation, a statistically rigorous approach that approximates missing data and preserves sample size, may be an improvement over complete case analysis. PURPOSE The present study aims to evaluate the impact of using multiple imputation in comparison with complete case analysis for assessing the associations between preoperative laboratory values and adverse outcomes following anterior cervical discectomy and fusion (ACDF) procedures. STUDY DESIGN/SETTING This is a retrospective review of prospectively collected data. PATIENT SAMPLE Patients undergoing one-level ACDF were identified in NSQIP 2012-2015. OUTCOME MEASURES Perioperative adverse outcome variables assessed included the occurrence of any adverse event, severe adverse events, and hospital readmission. METHODS Missing preoperative albumin and hematocrit values were handled using complete case analysis and multiple imputation. These preoperative laboratory levels were then tested for associations with 30-day postoperative outcomes using logistic regression. RESULTS A total of 11,999 patients were included. Of this cohort, 63.5% of patients had missing preoperative albumin and 9.9% had missing preoperative hematocrit. When using complete case analysis, only 4,311 patients were studied. The removed patients were significantly younger, healthier, of a common body mass index, and male. Logistic regression analysis failed to identify either preoperative hypoalbuminemia or preoperative anemia as significantly associated with adverse outcomes. When employing multiple imputation, all 11,999 patients were included. Preoperative hypoalbuminemia was significantly associated with the occurrence of any adverse event and severe adverse events. Preoperative anemia was significantly associated with the occurrence of any adverse event, severe adverse events, and hospital readmission. CONCLUSIONS Multiple imputation is a rigorous statistical procedure that is being increasingly used to address missing values in large datasets. Using this technique for ACDF avoided the loss of cases that may have affected the representativeness and power of the study and led to different results than complete case analysis. Multiple imputation should be considered for future spine studies.