Amy M. Cizik

Using the spine surgical invasiveness index to identify risk of surgical site infection: a multivariate analysis.

BACKGROUND Surgical site infection after spine surgery is a well-known complication that can result in poor outcomes, arthrodesis-site nonunion, and neurological injury. We hypothesized that a higher surgical invasiveness score will increase the risk for surgical site infection following spine surgery. METHODS Data were examined from patients undergoing any type of spinal surgery from January 1, 2003, to December 31, 2004, at two academic hospitals. The surgical invasiveness index is a previously validated instrument that accounts for the number of vertebral levels decompressed, arthrodesed, or instrumented as well as the surgical approach. Relative risks and 95% confidence intervals were calculated for each of the categorical variables. Multivariate binomial stepwise logistic regression was used to examine the association between surgical invasiveness and surgical site infection requiring a return to the operating room for treatment, adjusting for confounding risk factors. RESULTS The regression analysis of 1532 patients who were evaluated for surgical site infection identified the following significant risk factors for surgical site infection: a body mass index of >35 (relative risk, 2.24 [95% confidence interval, 1.21 to 3.86]; p = 0.01), hypertension (relative risk, 1.73 [95% confidence interval, 1.05 to 2.85]; p = 0.03), thoracic surgery versus cervical surgery (relative risk, 2.57 [95% confidence interval, 1.20 to 5.60]; p = 0.01), lumbosacral surgery versus cervical surgery (relative risk, 2.03 [95% confidence interval, 1.10 to 4.05]; p = 0.02), and a surgical invasiveness index of >21 (relative risk, 3.15 [95% confidence interval, 1.37 to 6.99]; p = 0.01). CONCLUSIONS Patients undergoing more invasive spine surgery as measured with the surgical invasiveness index had greater risk for having a surgical site infection that required a return to the operating room for treatment. Surgical invasiveness was the strongest risk factor for surgical site infection, even after adjusting for medical comorbidities, age, and other known risk factors. The magnitude of this association should be considered during surgical decision-making and intraoperative and postoperative care of the patient. These findings further validate the importance of the invasiveness index when performing safety and clinical outcome comparisons for spine surgery.

Survival of tumor megaprostheses replacements about the knee

Limb salvage surgery is an effective procedure with a low risk of tumor recurrence. In an attempt to define the incidence of implant failure at 2, 5, and 10 years postoperatively, we retrospectively reviewed implant survival in a group (n = 105) of pediatric (< 18 years of age) and adult patients who were treated with distal femoral and/or proximal tibial implants for extremity tumors. Issues regarding the timing of failure, reason for failure, and whether pediatric patients had higher rates of failure were posed as secondary questions. The median followup was 57 months (1-235 months). Thirty-two (32/105, 31%) patients had 42 implant failures. The mean prosthesis Kaplan-Meier survivorship of the index group was 84% at 2 years, 73% at 5 years, and 59% at 10 years. Forty-seven percent of all failures occurred within 2 years postoperatively, and 69% occurred within 5 years postoperatively. Pediatric patients had a higher failure rate than adults (42% versus 24%). Aseptic loosening was the most common reason for failure (n = 18/32; 56%). The incidence of failure in tumor megaprostheses is similar to early published literature and the incidence of these failures is highest within the first 3 years.Level of Evidence: Therapeutic study, level IV. See Guidelines for Authors for a complete description of levels of evidence.

Risk factors for medical complication after lumbar spine surgery

Study Design. Multivariate analysis of prospectively collected registry data. Objective. Using multivariate analysis to determine significant risk factors for medical complication after lumbar spine surgery. Summary of Background Data. Several studies have examined the occurrence of medical complication after spine surgery. However, many of these studies have been done utilizing large national databases. Although these allow for analysis of thousands of patients, potentially influential covariates are not accounted for in these retrospective studies. Furthermore, the accuracy of these retrospective data collection in these databases has been called into question. Methods. The Spine End Results Registry (2003–2004) is a collection of prospectively collected data on all patients who underwent spine surgery at our two institutions. Extensive demographic and medical information were prospectively recorded as described previously by Mirza et al. Complications were defined in detail a priori and were prospectively recorded for at least 2 years after surgery. We analyzed risk factors for medical complication after lumbar spine surgery using univariate and multivariate analysis. Results. We analyzed data from 767 patients who met out inclusion criteria. The cumulative incidences of complication after lumbar spine surgery per organ system are as follows: cardiac, 13%; pulmonary, 7%; gastrointestinal, 6.7%; neurological, 8.2%; hematological, 17.5%; and urologic complications, 10.3%. The occurrence of cardiac or respiratory complication after lumbar spine surgery was significantly associated with death within 2 years (relative risk: 6.09 and 10.9, respectively). Several significant risk factors were identified for organ-specific complications. Among these, surgical invasiveness appeared to be the largest risk factor for cardiac, pulmonary, neurological, and hematological complications. Conclusion. Risk factors identified in this study can be beneficial to clinicians and patients alike when considering surgical treatment of the lumbar spine. Future analyses and models that predict the occurrence of medical complication after lumbar spine surgery may be of further benefit for surgical decision making.

Risk Factors for Medical Complication After Lumbar Spine Surgery A Multivariate Analysis of 767 Patients

Study Design. Multivariate analysis of prospectively collected registry data. Objective. Using multivariate analysis to determine significant risk factors for medical complication after cervical spine surgery. Summary of Background Data. Several studies have examined the occurrence of medical complication after spine surgery. However, many of these studies have been done using large national databases. While these allow for analysis of thousands of patients, potentially influential covariates are not accounted for in these retrospective studies. Furthermore, the accuracy of these retrospective data collection in these databases has been called into question. Methods. The Spine End Results Registry (2003–2004) is a repository of prospectively collected data on all patients who underwent spine surgery at our 2 institutions. Extensive demographic and medical information was prospectively recorded. Complications were defined in detail a priori and were prospectively recorded for at least 2 years after surgery. We analyzed risk factors for medical complication after lumbar spine surgery, using univariate and multivariate analyses. Results. We analyzed data from 582 patients who met our inclusion criteria. The cumulative incidences of complication after cervical spine surgery per organ system are as follows: cardiac, 8.4%; pulmonary, 13%; gastrointestinal, 3.9%; neurological, 7.4%; hematological, 10.8%; and urologic complications, 9.2%. The occurrence of cardiac or respiratory complication after cervical spine surgery was significantly associated with death within 2 years (relative risk, 4.32, 6.43, respectively). Relative risk values with 95% confidence intervals and P values are reported. Conclusion. Risk factors identified in this study can be beneficial to clinicians and patients alike when considering surgical treatment of the cervical spine. Future analyses and models that predict the occurrence of medical complication after cervical spine surgery may be of further benefit for surgical decision making.

Predicting medical complications after spine surgery: a validated model using a prospective surgical registry

BACKGROUND CONTEXT The possibility and likelihood of a postoperative medical complication after spine surgery undoubtedly play a major role in the decision making of the surgeon and patient alike. Although prior study has determined relative risk and odds ratio values to quantify risk factors, these values may be difficult to translate to the patient during counseling of surgical options. Ideally, a model that predicts absolute risk of medical complication, rather than relative risk or odds ratio values, would greatly enhance the discussion of safety of spine surgery. To date, there is no risk stratification model that specifically predicts the risk of medical complication. PURPOSE The purpose of this study was to create and validate a predictive model for the risk of medical complication during and after spine surgery. STUDY DESIGN/SETTING Statistical analysis using a prospective surgical spine registry that recorded extensive demographic, surgical, and complication data. Outcomes examined are medical complications that were specifically defined a priori. This analysis is a continuation of statistical analysis of our previously published report. METHODS Using a prospectively collected surgical registry of more than 1,476 patients with extensive demographic, comorbidity, surgical, and complication detail recorded for 2 years after surgery, we previously identified several risk factor for medical complications. Using the beta coefficients from those log binomial regression analyses, we created a model to predict the occurrence of medical complication after spine surgery. We split our data into two subsets for internal and cross-validation of our model. We created two predictive models: one predicting the occurrence of any medical complication and the other predicting the occurrence of a major medical complication. RESULTS The final predictive model for any medical complications had a receiver operator curve characteristic of 0.76, considered to be a fair measure. The final predictive model for any major medical complications had receiver operator curve characteristic of 0.81, considered to be a good measure. The final model has been uploaded for use on SpineSage.com. CONCLUSION We present a validated model for predicting medical complications after spine surgery. The value in this model is that it gives the user an absolute percent likelihood of complication after spine surgery based on the patients comorbidity profile and invasiveness of surgery. Patients are far more likely to understand an absolute percentage, rather than relative risk and confidence interval values. A model such as this is of paramount importance in counseling patients and enhancing the safety of spine surgery. In addition, a tool such as this can be of great use particularly as health care trends toward pay-for-performance, quality metrics, and risk adjustment. To facilitate the use of this model, we have created a website (SpineSage.com) where users can enter in patient data to determine likelihood of medical complications after spine surgery.

Predicting surgical site infection after spine surgery: a validated model using a prospective surgical registry

BACKGROUND CONTEXT The impact of surgical site infection (SSI) is substantial. Although previous study has determined relative risk and odds ratio (OR) values to quantify risk factors, these values may be difficult to translate to the patient during counseling of surgical options. Ideally, a model that predicts absolute risk of SSI, rather than relative risk or OR values, would greatly enhance the discussion of safety of spine surgery. To date, there is no risk stratification model that specifically predicts the risk of medical complication. PURPOSE The purpose of this study was to create and validate a predictive model for the risk of SSI after spine surgery. STUDY DESIGN This study performs a multivariate analysis of SSI after spine surgery using a large prospective surgical registry. Using the results of this analysis, this study will then create and validate a predictive model for SSI after spine surgery. PATIENT SAMPLE The patient sample is from a high-quality surgical registry from our two institutions with prospectively collected, detailed demographic, comorbidity, and complication data. OUTCOME MEASURES An SSI that required return to the operating room for surgical debridement. MATERIALS AND METHODS Using a prospectively collected surgical registry of more than 1,532 patients with extensive demographic, comorbidity, surgical, and complication details recorded for 2 years after the surgery, we identified several risk factors for SSI after multivariate analysis. Using the beta coefficients from those regression analyses, we created a model to predict the occurrence of SSI after spine surgery. We split our data into two subsets for internal and cross-validation of our model. We created a predictive model based on our beta coefficients from our multivariate analysis. RESULTS The final predictive model for SSI had a receiver-operator curve characteristic of 0.72, considered to be a fair measure. The final model has been uploaded for use on SpineSage.com. CONCLUSIONS We present a validated model for predicting SSI after spine surgery. The value in this model is that it gives the user an absolute percent likelihood of SSI after spine surgery based on the patients comorbidity profile and invasiveness of surgery. Patients are far more likely to understand an absolute percentage, rather than relative risk and confidence interval values. A model such as this is of paramount importance in counseling patients and enhancing the safety of spine surgery. In addition, a tool such as this can be of great use particularly as health care trends toward pay for performance, quality metrics (such as SSI), and risk adjustment. To facilitate the use of this model, we have created a Web site (SpineSage.com) where users can enter patient data to determine likelihood for SSI.

An Association of Lateral Knee Sagittal Anatomic Factors with Non-Contact ACL Injury: Sex or Geometry?

BACKGROUND Lateral tibiofemoral articular geometry may play a role in the development of non-contact anterior cruciate ligament (ACL) injuries. We hypothesized that athletes who had sustained an ACL injury would demonstrate more highly convex articular surfaces in the lateral compartment of the knee compared with activity-matched athletes who had not sustained an ACL injury, and that women would demonstrate greater absolute and relative convexity of these articular surfaces than men. METHODS One hundred and twelve athletes with a non-contact ACL injury and sixty-one activity-matched athletes without an ACL injury were studied. Three blinded observers measured the articular geometry in the mid-lateral sagittal plane with use of magnetic resonance imaging. The tibial plateau radius of curvature (TPr), distal femoral radius of curvature (Fr), maximal femoral anteroposterior articular length (FAP), and maximal tibial anteroposterior articular length (TPAP) were recorded. The Fr:TPr and FAP:TPAP ratios were also calculated to adjust for size variations. The intraclass correlation coefficient and the two-sample Student t test were used to compare quantitative variables. All data were found to follow a normal distribution. RESULTS When data for male and female patients were combined, the mean TPr, Fr, and TPAP values were significantly smaller in the ACL-injured patients than in the uninjured patients (33.9 compared with 37.5 mm, p = 0.005; 24.3 compared with 25.1 mm, p = 0.04; and 31.5 compared with 33.1 mm, p = 0.007; respectively). The mean FAP value did not differ significantly between the ACL-injured and uninjured patients but the difference in the mean FAP:TPAP value was significant (p = 0.003). When only male patients were analyzed, the mean TPr, Fr, and TPAP values were also significantly smaller in the ACL-injured patients than in the uninjured patients (35.5 compared with 41.1 mm, p = 0.002; 25.5 compared with 26.7 mm, p = 0.001; and 33.0 compared with 35.5 mm, p = 0.0002; respectively). The mean FAP value did not differ significantly between the ACL-injured and uninjured male patients, but the difference in the mean FAP:TPAP value was significant (p = 0.0005). In contrast, when only female patients were analyzed, none of the mean values differed significantly between the ACL-injured and uninjured patients. The FAP:TPAP and Fr:TPr values did not differ significantly among the ACL-injured male patients, injured female patients, and uninjured female patients. CONCLUSIONS All female patients (both ACL-injured and uninjured) and ACL-injured male patients shared a common lateral knee geometry characterized by a smaller tibial plateau length relative to the femur and by more convex articulating surfaces of the proximal aspect of the tibia and the distal aspect of the femur. Shorter, more highly convex articulating surfaces may be inherently less stable with regard to anterior tibial translation and rotation. These findings may partially explain the greater overall predisposition of women compared with men toward ACL injury as well as why some studies have demonstrated no sex differences in graft reinjury after ACL reconstruction.

Medicaid status is associated with higher complication rates after spine surgery

Study Design. Multivariate analysis of prospectively collected registry data. Objective. To determine the effect of payor status on complication rates after spine surgery. Summary of Background Data. Understanding the risk of perioperative complications is an essential aspect in improving patient outcomes. Previous studies have looked at complication rates after spine surgery and factors related to increased perioperative complications. In other areas of medicine, there has been a growing body of evidence gathered to evaluate the role of payor status on outcomes and complications. Several studies have found increased complication rates and inferior outcomes in the uninsured and Medicaid insured. Methods. The Spine End Results Registry (2003–2004) is a collection of prospectively collected data on all patients who underwent spine surgery at our 2 institutions. Extensive demographic data, including payor status, and medical information were prospectively recorded as described previously by Mirza et al.16 Medical complications were defined in detail a priori and were prospectively recorded for at least 2 years after surgery. Using univariate and multivariate analysis, we determined risk of postoperative medical complications dependent on payor status. Results. A total of 1591 patients underwent spine surgery in 2003 and 2004 that met our criteria and were included in our analysis. With the multivariate analysis and by controlling for age, patients whose insurer was Medicaid had a 1.68 odds ratio (95% confidence interval: 1.23–2.29; P = 0.001) of having any adverse event when compared with the privately insured. Conclusion. After univariate and multivariate analyses, Medicaid insurance status was found to be a risk factor for postoperative complications. This corresponds to an ever-growing body of medical literature that has shown similar trends and raises the concern of underinsurance. Level of Evidence: 2

Perceptions of the Screening Mammography Experience by Hispanic and Non-Hispanic White Women

PURPOSE To uncover perceptive differences in mammography experiences (from scheduling the mammography appointment to receipt and reporting of mammography results) between women from two different racial/ethnic groups. METHODS Focus groups (n = 9) were conducted with Hispanic, and non-Hispanic White women (n = 88) who were aged 40 years or older and had a mammogram within the preceding 36 months. We used a qualitative ethnographic approach with content analysis to identify key categories present in the transcripts and domain analysis to discover domains of meaning. A matrix was designed to determine which domains differed by racial/ethnic group. The primary mammography-related topics of focus group discussion included 1) the scheduling process, 2) the day of the mammogram, 3) receipt of results, and 4) recommendations to improve the mammography process. MAIN FINDINGS Six domains uniquely described issues women of the differing racial/ethnic groups experience and perceive as important. Hispanic women highlighted embarrassment surrounding the examination and fear of negative news about their mammography results. Non-Hispanic White women focused on instructions given before or during the examination as a critical process feature. CONCLUSIONS Perceptions of the mammography experience vary by race/ethnicity. Mammography experiences might be improved through enhanced sensitivity of healthcare personnel to cultural differences in perceptions of mammogram testing. Future research to investigate the extent to which the domains of meanings uncovered in this study influence a womens decision to return for routine mammograms would be of great value.

Validation of the SF-6D Health State Utilities Measure in Lower Extremity Sarcoma

Aim. Health state utilities measures are preference-weighted patient-reported outcome (PRO) instruments that facilitate comparative effectiveness research. One such measure, the SF-6D, is generated from the Short Form 36 (SF-36). This report describes a psychometric evaluation of the SF-6D in a cross-sectional population of lower extremity sarcoma patients. Methods. Patients with lower extremity sarcoma from a prospective database who had completed the SF-36 and Toronto Extremity Salvage Score (TESS) were eligible for inclusion. Computed SF-6D health states were given preference weights based on a prior valuation. The primary outcome was correlation between the SF-6D and TESS. Results. In 63 pairs of surveys in a lower extremity sarcoma population, the mean preference-weighted SF-6D score was 0.59 (95% CI 0.4–0.81). The distribution of SF-6D scores approximated a normal curve (skewness = 0.11). There was a positive correlation between the SF-6D and TESS (r = 0.75, P < 0.01). Respondents who reported walking aid use had lower SF-6D scores (0.53 versus 0.61, P = 0.03). Five respondents underwent amputation, with lower SF-6D scores that approached significance (0.48 versus 0.6, P = 0.06). Conclusions. The SF-6D health state utilities measure demonstrated convergent validity without evidence of ceiling or floor effects. The SF-6D is a health state utilities measure suitable for further research in sarcoma patients.