Interrater and Intrarater Reliability of the Vertebral Bone Quality Score

BACKGROUND

Vertebral bone quality had a significant impact on postoperative outcomes in spinal fusion surgery. New magnetic resonance imaging-based measures, such as the Vertebral Bone Quality (VBQ) score, may allow for bone quality assessment without the radiation associated with conventional testing. In the present study, we sought to assess the intrarater and interrater reliability of VBQ scores calculated by medical professionals and trainees.

METHODS

Thirteen reviewers of various specialties and levels of training were recruited and asked to calculate VBQ scores for 30 patients at 2 time points separated by 2 months. Scored volumes were acquired from patients treated for both degenerative and oncologic indications. Intrarater and interrater agreement, quantified by intraclass correlation coefficient (ICC), was assessed using 2-way random effects modeling. Square-weight Cohen κ and Kendall Tau-b were used to determine whether raters assigned similar scores during both evaluations.

RESULTS

All raters showed moderate to excellent reliability for VBQ score (ICC 0.667-0.957; κ0.648-0.921) and excellent reliability for all constituent components used to calculate VBQ score (ICC all ≥0.97). Interrater reliability was also found to be good for VBQ score on both the first (ICC = 0.818) and second (ICC = 0.800) rounds of assessment; scores for the constituent component all had ICC values ≥0.97 for the constituent components.

CONCLUSIONS

The VBQ score appears to have both good intrarater and interrater reliability. In addition, there appeared to be no correlation between score reliability and level of training. External validation and further investigations of its ability to accurately model bone biomechanical properties are necessary.

Use of electromyography to predict likelihood of recovery following C5 palsy after posterior cervical spine surgery

BACKGROUND

C5 palsy affects approximately 5% to 10% of patients undergoing cervical spine surgery. It has a significant negative impact on patient quality-of-life outcomes and healthcare costs. Although >80% of patients improve, some are left with persistent, debilitating deficits. Our objective was to examine if electrodiagnostic testing could be used to successfully identify patients likely to experience complete, partial, and no recovery.

METHODS

Patients undergoing posterior cervical decompression and fusion at a single institution over a 10-year period were identified. Those experiencing postoperative C5 palsy were included. Outcomes examined included motor recovery of the affected deltoid as a function of time, and changes in electrodiagnostic testing as a function of time since injury. Electrodiagnostic testing included electromyography and was sub-analyzed by time of acquisition postinjury. Deltoid strength was graded on manual motor testing using the 5-point medical research council grading system.

RESULTS

Of 77 patients experiencing C5 palsy, 29 had postoperative electrodiagnostic testing. Patients experiencing complete recovery on average achieved functional (4/5) strength by 6-weeks post injury and 4+ per 5 strength by 6-months. Those experiencing partial recovery only achieved antigravity strength (3/5) by 6-weeks and low-function (4-/5) strength by 6-months. Electrodiagnostic testing performed 6-weeks to 6-months postinjury demonstrated that those experiencing complete recovery were more likely to have normal motor unit (MU) recruitment than those experiencing partial (p<.001) or no recovery (p=.008). The presence of ≥2+ fibrillation on tests acquired ≤6-weeks of injury identified patients unlikely to experience any recovery with a positive predictive value (PPV) of 88.9%. The presence of normal MU recruitment on tests acquired 6-weeks to 6-months postinjury identified patients likely to experience complete recovery with a PPV of 87.5%.

CONCLUSIONS

Electrodiagnostic testing may be a valuable means of differentiating between patients with C5 palsy likely to experience complete, partial, or no recovery. Testing between 6-weeks and 6-months post onset may aid in identifying those least likely to have a complete recovery. No MUs at 4 to 6-months, or reduced units with strength that is not improving, portends a poor long-term outcome. In this population, peripheral nerve transfers may be considered sooner.

Postoperative Delayed Cervical Palsies: Understanding the Etiology

STUDY DESIGN

Retrospective study.

OBJECTIVE

This study reviews 1,768 consecutive cervical decompressions with or without instrumented fusion to identify patient-specific and procedural risk factors significantly correlated with the development of delayed cervical palsy (DCP).

METHODS

Baseline demographic and procedural information was collected from the electronic medical record. Particular attention was devoted to reviewing each chart for recognized risk factors of postsurgical inflammatory neuropathy: autoimmune disease, blood transfusions, diabetes, and smoking.

RESULTS

Of 1,669 patients, 56 (3.4%) developed a DCP. Although 71% of the palsies involved C5, 55% of palsies were multimyotomal and 18% were bilateral. Significant risk factors on univariate analysis included age (p = 0.0061, odds ratio [OR] = 1.07, 95% confidence interval [CI] 1.008 to 1.050), posterior instrumented fusion (p < 0.0001, OR = 3.30, 95% CI 1.920 to 5.653), prone versus semisitting/sitting position (p = 0.0036, OR = 3.58, 95% CI 1.451 to 11.881), number of operative levels (p < 0.0001, OR = 1.42, 95% CI 1.247 to 1.605), intraoperative transfusions (p = 0.0231, OR = 2.57, 95% CI 1.152 to 5.132), and nonspecific autoimmune disease (p = 0.0107, OR = 3.83, 95% CI 1.418 to 8.730). On multivariate analysis, number of operative levels (p = 0.0053, OR = 1.27, 95% CI 1.075 to 1.496) and nonspecific autoimmune disease (p = 0.0416, OR 2.95, 95% CI 1.047 to 7.092) remained significant.

CONCLUSIONS

Although this study partially supports a mechanical etiology in the pathogenesis of a DCP, we also describe a notable correlation with autoimmune risk factors. Bilateral and multimyotomal involvement provides additional support that some DCPs may result from an inflammatory response and thus an underlying multifactorial etiology for this complication.

Understanding the Impact of Obesity on Short-term Outcomes and In-hospital Costs After Instrumented Spinal Fusion

BACKGROUND

Obesity rates continue to rise along with the number of obese patients undergoing elective spinal fusion.

OBJECTIVE

To evaluate the impact of obesity on resource utilization and early complications in patients undergoing surgery for degenerative spine disease.

METHODS

A single-institution retrospective analysis was conducted on patients with degenerative spine disease requiring instrumentation between 2008 and 2012. The 801 identified patients were grouped based on a body mass index (BMI) of <30 (nonobese, n = 478), ≥30 and <40 (obese, n = 283), and alternatively BMIs of ≥40 (morbidly obese, n = 40). Baseline characteristics, surgical outcomes and requirements, complications, and cost were compared. Logistic and linear regression analyses were used to determine the strength of association between obesity and outcomes for categorical and continuous data, respectively.

RESULTS

Significant differences were found in comorbidities between cohorts. Multivariate analysis revealed significant associations between obesity and longer anesthesia times (30 minutes, P = .008), and surgical times (24 minutes, P = .02). Additionally, there was a 2.8 times higher rate of wound complications in obese patients (4.2% vs 1.5, P = .03), and 2.5 times higher rate of major medical complications (7.8% vs 3.1, P = .01). Morbid obesity resulted in a 10 times higher rate of wound complications (P < .001). Morbid obesity resulted in a $9078 (P = .005) increase in overall cost of care.

CONCLUSION

Increased BMI is associated with longer operative times, increased complication rates, and increased cost independent of comorbidities. These effects are more pronounced with morbidly obese patients, further supporting a role for preoperative weight loss.

The Impact of Obesity on Perioperative Resource Utilization after Elective Spine Surgery for Degenerative Disease

Study Design Retrospective case series. Objective To determine the effect of obesity on the resource utilization and cost in 3270 consecutive patients undergoing elective noninstrumented decompressive surgeries for degenerative spine disease at Mayo Clinic Rochester between 2005 and 2012. Methods Groups were assessed for baseline differences (age, gender, and American Society of Anesthesiologists [ASA] classification, procedure type, and number of operative levels). Outcome variables included the transfusion requirements during surgery, the total anesthesia and surgical times, intensive care unit (ICU) admissions, standardized costs, as well as the ICU and hospital length of stay (LOS). Regression analysis was used to evaluate for strength of association between obesity and outcome variables. Results Baseline differences between the groups (nonobese: n = 1,853; obese: n = 1,417) were found with respect to age, ASA class, gender, procedure type, and number of operative levels. After correcting for differences, we found significant associations between obesity and surgical (p < 0.0001) and anesthesia times (p < 0.0001) and hospital LOS (p < 0.0001). Additionally, ICU admission rates (p = 0.02) and requirement for postoperative ventilation (p = 0.048) were significantly higher in obese patients. Finally, mean difference in total cost ($1,632, p < 0.0001) was significantly higher for the obese cohort. Conclusion Obesity is associated with increased resource utilization and cost in patients undergoing a noninstrumented decompressive surgery for degenerative spine disease.