Development of a mapping function ("crosswalk") for the conversion of scores between the Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI).

INTRODUCTION: The Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) are two commonly used self-rating outcome instruments in patients with lumbar spinal disorders. No formal crosswalk between them exists that would otherwise allow the scores of one to be interpreted in terms of the other. We aimed to create such a mapping function. METHODS: We performed a secondary analysis of ODI and COMI data previously collected from 3324 patients (57 ± 17y; 60.3% female) at baseline and 1y after surgical or conservative treatment. Correlations between scores and Cohen's kappa for agreement (κ) regarding achievement of the minimal clinically important change (MCIC) score on each instrument (ODI, 12.8 points; COMI, 2.2 points) were calculated, and regression models were built. The latter were tested for accuracy in an independent set of registry data from 634 patients (60 ± 15y; 56.8% female). RESULTS: All pairs of measures were significantly positively correlated (baseline, 0.73; 1y follow-up (FU), 0.84; change-scores, 0.73). MCIC for COMI was achieved in 53.9% patients and for ODI, in 52.4%, with 78% agreement on an individual basis (κ = 0.56). Standard errors for the regression slopes and intercepts were low, indicating excellent prediction at the group level, but root mean square residuals (reflecting individual error) were relatively high. ODI was predicted as COMI × 7.13-4.20 (at baseline), COMI × 6.34 + 2.67 (at FU) and COMI × 5.18 + 1.92 (for change-score); COMI was predicted as ODI × 0.075 + 3.64 (baseline), ODI × 0.113 + 0.96 (FU), and ODI × 0.102 + 1.10 (change-score). ICCs were 0.63-0.87 for derived versus actual scores. CONCLUSION: Predictions at the group level were very good and met standards justifying the pooling of data. However, we caution against using individual values for treatment decisions, e.g. attempting to monitor patients over time, first with one instrument and then with the other, due to the lower statistical precision at the individual level. The ability to convert scores via the developed mapping function should open up more centres/registries for collaboration and facilitate the combining of data in meta-analyses.

Development of a machine-learning based model for predicting multidimensional outcome after surgery for degenerative disorders of the spine.

BACKGROUND: It is clear that individual outcomes of spine surgery can be quite heterogeneous. When consenting a patient for surgery, it is important to be able to offer an individualized prediction regarding the likely outcome. This study used a comprehensive set of data collected over 12 years in an in-house registry to develop a parsimonious model to predict the multidimensional outcome of patients undergoing surgery for degenerative pathologies of the thoracic, lumbar or cervical spine. METHODS: Data from 8374 patients (mean age 63.9 (14.9-96.3) y, 53.4% female) were used to develop a model to predict the 12-month scores for the Core Outcome Measures Index (COMI) and its subdomain scores. The data were split 80:20 into a training and test set. The top predictors were selected by applying recursive feature elimination based on LASSO cross validation models. Based on the 111 top predictors (contained within 20 variables), Ridge cross validation models were trained, validated, and tested for each of 9 outcome domains, for patients with either "Back" (thoracic/lumbar spine) or "Neck" (cervical spine) problems (total 18 models). RESULTS: Among the strongest outcome predictors in most models were: preoperative scores for almost all COMI items (especially axial pain (back or neck) and peripheral pain (leg/buttock or arm/shoulder)), catastrophizing, fear avoidance beliefs, comorbidity, age, BMI, nationality, previous spine surgery, type and spinal level of intervention, number of affected levels, and surgeon seniority. The R2 of the models on the validation/test sets averaged 0.16/0.13. A preliminary online tool was programmed to present the predicted outcomes for individual patients, based on their presenting characteristics. https://linkup.kws.ch/prognostictool . CONCLUSION: The models provided estimates to enable a bespoke prediction of the outcome of surgery for individual patients with varying degenerative pathologies and baseline characteristics. The models form the basis of a simple, freely-available online prognostic tool developed to improve access to and usability of prognostic information in clinical practice. It is hoped that, following confirmation of its validity and practical utility, the tool will ultimately serve to facilitate decision-making and the management of patients' expectations.

Shorter and sweeter: the 16-item version of the SRS questionnaire shows better structural validity than the 20-item version in young patients with spinal deformity.

PURPOSE: In patients with adult spinal deformity, it was previously shown that 16 of the non-management items of the SRS-instrument showed a better fit to the theoretical four-factor model (pain, function, self-image, mental health) than did all 20 items. Whether the same phenomenon is observed in data from younger (< 20y) patients, for whom the questionnaire was originally designed, is not currently known. METHODS: Confirmatory factor analysis was used to evaluate the factor structure of the 20 non-management items of the SRS-instrument completed by 3618 young patients with spinal deformity (75.5% female; mean age, 15.0 ± 2.0 years) and of its equivalence across language versions (2713 English-speaking, 270 Spanish, 264 German, 223 Italian, and 148 French). The root mean square error of approximation (RMSEA) and comparative fit index (CFI) indicated model fit. RESULTS: Compared with the 20-item version, the 16-item solution significantly increased the fit (p < 0.001) across all language versions, to achieve good model fit (CFI = 0.96, RMSEA = 0.06). For both 16-item and 20-item models, equivalence across languages was not reached, with some items showing weaker item-loading for some languages, in particular German and French. CONCLUSION: In patients with adolescent idiopathic scoliosis, the shorter 16-item version showed a better fit to the intended 4-factor structure of the SRS-instrument. The wording of some of the items, and/or their equivalence across language versions, may need to be addressed. Questionnaire completion can be a burden for patients; if a shorter, more structurally valid version is available, its use should be encouraged.

Patient-rated outcome after atlantoaxial (C1-C2) fusion: more than a decade of evaluation of 2-year outcomes in 126 patients.

INTRODUCTION: Various surgical techniques have been introduced for atlantoaxial (C1-C2) fusion, the most common being Magerl's (transarticular) or the Harms/Goel screw fixation. Common indications include degenerative osteoarthritis (OA), trauma or rheumatoid arthritis (RA). Only few, small studies have evaluated patient-reported outcomes after C1-C2 fusion. We investigated 2-year outcomes in a large series of consecutive patients undergoing isolated C1-C2 fusion. METHODS: We analysed prospectively collected data (2005-2016) from our Spine outcomes database, collected within the framework of EUROSPINE's Spine Tango Registry. It included 126 patients (34 (27%) men, 92 (73%) women; mean (SD) age 67 ± 19 y) who had undergone first-time isolated C1-C2 fusion (61% Magerl, 39% Harms(-Goel)) at least 2 years ago for OA (83 (66%)), RA (20 (16%)), fracture (15 (12%)) or other (8 (6%)). Patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10) and various single item outcomes. RESULTS: Questionnaires were returned by 118/126 (94%) patients, 2 years post-operative. Mean COMI scores showed a significant reduction from baseline: 6.9 ± 2.4 to 2.7 ± 2.5 (p < 0.0001). Overall, 75% patients achieved the MCIC of ≥ 2.2 points reduction in COMI and 88% reported a good global outcome. 91% patients were satisfied/very satisfied with their care. Self-reported complications were declared by 16% patients and further surgery at the same segment, by 2.5%. CONCLUSION: In this large series with almost complete follow-up, C1-C2 fusion showed extremely good results. Despite the complexity of the intervention, outcomes surpassed those typically reported for simple procedures such as ACDF and lumbar discectomy, suggesting reservations about the procedure should perhaps be reviewed.

The Impact of Corrective Surgery on Health-Related Quality of Life Subclasses in Adult Scoliosis: Will Degree of Correction Prognosticate Degree of Improvement?

PURPOSE: Objectives in scoliosis corrective surgery include restoration of normal sagittal and coronal parameters to achieve patient satisfaction. HRQLs improvements remain limited after corrective surgery. The aim of this study was to evaluate the HRQL subclass variability specific to the sagittal and coronal correction in adult scoliosis surgery. METHODS: This multi-centre prospective analysis of consecutive adult spinal deformity (ASD) patients, from five European centres, only included multilevel instrumentation for scoliosis. d-(delta) values for each parameter represented pre to post-operative changes. Parameters included demographics, baseline, 1- and 2-year. HRQL outcomes (Oswestry disability index (ODI), Scoliosis Research Society (SRS)-22 and Short Form (SF36)), sagittal correction including relative spinopelvic alignment (dRSA) and coronal correction including major Cobb (dCobb) angles. RESULTS: A total of 353 patients reached 1-year and 2-year follow up. All HRQL total scores significantly improved postoperatively, including ODI, SRS-22 and SF36. HRQL subclasses which displayed persistent improvements correlated to dRSA included sex-life, self-image, fatigue, vitality, social functioning. The only HRQL subclass improvement that correlated with dCobb was self-image. CONCLUSION: Adult scoliosis surgery improves overall HRQL, having a minimal effect on each variable. Importantly, greater coronal deformity correction affects only greater self-image scores, whereas with greater sagittal correction there are many greater HRQL sub-class impacts. Correction and restoration of coronal balance is one of the surgical goals in adult scoliosis but the degree to which Cobb angle is corrected, apart from self-image, does not correlate with gains in sub-classes of HRQL. These results need to be taken into account when planning surgery.

What level of symptoms are patients with adult spinal deformity prepared to live with? A cross-sectional analysis of the 12-month follow-up data from 1043 patients.

INTRODUCTION: Previous studies suggest that a meaningful and easily understood measure of treatment outcome may be the proportion of patients who are in a "patient acceptable symptom state" (PASS). We sought to quantify the score equivalent to PASS for different outcome instruments, in patients with adult spinal deformity (ASD). METHODS: We analysed the following 12-month questionnaire data from the European Spine Study Group (ESSG): Oswestry Disability Index (ODI; 0-100); Numeric Rating Scales (NRS; 0-10) for back/leg pain; Scoliosis Research Society (SRS) questionnaire; and an item "if you had to spend the rest of your life with the symptoms you have now, how would you feel about it?" (5-point scale, dichotomised with top 2 responses "somewhat satisfied/very satisfied" being considered PASS+, everything else PASS-). Receiver operating characteristics (ROC) analyses indicated the cut-off scores equivalent to PASS+. RESULTS: Out of 1043 patients (599 operative, 444 non-operative; 51 ± 19 years; 84% women), 42% reported being PASS+ at 12 months' follow-up. The ROC areas under the curve were 0.71-0.84 (highest for SRS subscore), suggesting the questionnaire scores discriminated well between PASS+ and PASS-. The scores corresponding to PASS+ were > 3.5 for the SRS subscore (> 3.3-3.8 for SRS subdomains); ≤ 18 for ODI; and ≤ 3 for NRS pain. There were slight differences in cut-offs for subgroups of age, treatment type, aetiology, baseline symptoms, and sex. CONCLUSION: Most interventions for ASD improve patients' complaints but do not totally eliminate them. Reporting the percentage achieving a score equivalent to an "acceptable state" may represent a more stringent and discerning target for denoting treatment success in ASD. These slides can be retrieved under Electronic Supplementary Material.

Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier.

STUDY DESIGN: Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients. OBJECTIVE: To Validate Schwab's classification accuracy for surgical indication, and to evaluate a simplified sagittal modifier. SUMMARY OF BACKGROUND DATA: The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence-lumbar lordosis (PI-LL). The high number of classification possibilities makes it complex to use. METHODS: Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant. RESULTS: Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups. CONCLUSIONS: Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making. LEVEL OF EVIDENCE: Level II.

Factors associated with having an indication for surgery in adult spinal deformity: an international european multicentre study.

PURPOSE: The aim of this study was to evaluate factors that distinguish between patients with adult spinal deformity (ASD) with and without an indication for surgery, irrespective of their final treatment. METHODS: Baseline variables (demographics, medical history, outcome measures, coronal, sagittal and neurologic parameters) were evaluated in a multicentre, prospective cohort of patients with ASD. Multivariable analyses were carried out for idiopathic and degenerative patients separately with the dependent variable being "indication for surgery" and baseline parameters as independent variables. RESULTS: In total, 342 patients with degenerative ASD and 624 patients with idiopathic ASD were included in the multivariable models. In patients with degenerative ASD, the parameters associated with having an indication for surgery were greater self-rated disability on the Oswestry Disability Index [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.07] and a lower thoracic kyphosis (OR 0.97 95% CI 0.95-0.99), whereas in patients with idiopathic ASD, it was lower (worse) SRS self-image scores (OR 0.45 95% CI 0.32-0.64), a higher value for the major Cobb angle (OR 1.03 95% CI 1.01-1.05), lower age (OR 0.96 95% CI 0.95-0.98), prior decompression (OR 3.76 95% CI 1.00-14.08), prior infiltration (OR 2.23 95% CI 1.12-4.43), and the presence of rotatory subluxation (OR 1.98 95% CI 1.11-3.54) and sagittal subluxation (OR 4.38 95% CI 1.61-11.95). CONCLUSION: Specific sets of variables were found to be associated with an indication for surgery in patients with ASD. These should be investigated in relation to patient outcomes for their potential to guide the future development of decision aids in the treatment of ASD. These slides can be retrieved under Electronic Supplementary Material.

Factor analysis of the SRS-22 outcome assessment instrument in patients with adult spinal deformity.

PURPOSE: Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients. METHODS: Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation. RESULTS: The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample. CONCLUSION: We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

How does patient-rated outcome change over time following the surgical treatment of degenerative disorders of the thoracolumbar spine?

PURPOSE: Patient-rated measures are considered the gold standard for assessing the outcome of spine surgery, but there is no consensus on the appropriate timing of follow-up. Journals often demand a minimum 2-year follow-up, but the indiscriminate application of this principle may not be warranted. We examined the course of change in patient outcomes up to 5 years after surgery for degenerative spinal disorders. METHODS: The data were evaluated from 4287 consecutive patients (2287 women, 2000 men; aged 62 ± 15 years) with degenerative disorders of the thoracolumbar spine, undergoing first-time surgery at the given level between 01/01/2005 and 31/12/2011. The Core Outcome Measures Index (COMI; scored 0-10) was completed by 4012 (94%) patients preoperatively, 4008 (93%) at 3-month follow-up, 3897 (91%) at 1-year follow-up, 3736 (87%) at 2-year follow-up, and 3387 (79%) at 5-year follow-up. 2959 (69%) completed the COMI at all five time-points. RESULTS: The individual COMI change scores from preoperatively to the various follow-up time-points showed significant correlations ranging from r = 0.50 (for change scores at the earliest vs the latest follow-up) to r = 0.75 (for change scores after 12- vs 24-month follow-up). Concordance with respect to whether the minimum clinically important change score was achieved at consecutive time-points was also good (70-82%). COMI decreased significantly (p < 0.05) from preop to 3 months (by 3.6 ± 2.8 points) and from 3 to 12 months (by 0.3 ± 2.4 points), then levelled off up to 5 years (0.04-0.05 point change; p > 0.05). The course of change up to 12 months differed slightly (p < 0.05) depending on pathology/whether fusion was carried out. For patients undergoing simple decompression, 3-month follow-up was sufficient; those undergoing fusion continued to show further slight but significant change up to 12 months. CONCLUSIONS: Stable group mean COMI scores were observed for all patients from 12 months postoperatively onwards. The early postoperative results appeared to herald the longer term outcome. As such, a 'wait and see policy' in patients with a poor initial outcome at 3 months is not advocated. The insistence on a 2-year follow-up could result in a failure to intervene early to achieve better long-term outcomes.

A novel use of the Spine Tango registry to evaluate selection bias in patient recruitment into clinical studies: an analysis of patients participating in the Lumbar Spinal Stenosis Outcome Study (LSOS).

PURPOSE: Patients enrolled in clinical studies typically represent a sub-set of all who are eligible, and selection bias may compromise the generalizability of the findings. Using Registry data, we evaluated whether surgical patients recruited by one of the referring centres into the Lumbar Spinal Stenosis Outcome Study (LSOS; a large-scale, multicentre prospective observational study to determine the probability of clinical benefit after surgery) differed in any significant way from those who were eligible but not enrolled. METHODS: Data were extracted for all patients with lumbar spinal stenosis registered in our in-house database (interfaced to Eurospine's Spine Tango Registry) from 2011 to 2013. Patient records and imaging were evaluated in relation to the admission criteria for LSOS to identify those who would have been eligible for participation but were not enrolled (non-LSOS). The Tango surgery data and Core Outcome Measures Index (COMI) data at baseline and 3 and 12 months after surgery were analysed to evaluate the factors associated with LSOS enrolment or not. RESULTS: 514 potentially eligible patients were identified, of which 94 (18%) were enrolled into LSOS (range 2-48% for the 6 spine surgeons involved in recruiting patients) and 420 (82%) were not; the vast majority of the latter were due to non-referral to the study by the surgeon, with only 5% actually refusing participation. There was no significant difference in gender, age, BMI, smoking status, or ASA score between the two groups (p ≥ 0.18). Baseline COMI was significantly (p = 0.002) worse in the non-LSOS group (7.4 ± 1.9) than the LSOS group (6.7 ± 1.9). There were no significant group differences in any Tango surgery parameters (additional spine patholothegies, operation time, blood loss, complications, etc.) although significantly more patients in the non-LSOS group had a fusion procedure (38 vs 18% in LSOS; p = 0.0004). Postoperatively, neither the COMI nor its subdomain scores differed significantly between the groups (p > 0.05). Multiple logistic regression revealed that worse baseline COMI (p = 0.021), surgeon (p = 0.003), and having fusion (p = 0.014) predicted non-enrolment in LSOS. CONCLUSION: A high proportion of eligible patients were not enrolled in the study. Non-enrolment was explained in part by the specific surgeon, worse baseline COMI status, and having a fusion. The findings may reflect a tendency of the referring surgeon not to overburden more disabled patients and those undergoing more extensive surgery with the commitments of a study. Beyond these factors, non-enrolment appeared to be somewhat arbitrary, and was likely related to surgeon forgetfulness, time constraints, and administrative errors. Researchers should be aware of potential selection bias in their clinical studies, measure it (where possible) and discuss its implications for the interpretation of the study's findings.

Global tilt: a single parameter incorporating spinal and pelvic sagittal parameters and least affected by patient positioning.

PURPOSE: Regarding the close interaction between the spinal alignment and the pelvis orientation, no parameter is routinely used to describe and to evaluate the global spinopelvic balance, taking into account simultaneously the spinal part and the pelvic part of the global alignment. We described the global tilt (GT) that could analyze malalignment considering the spine and the pelvis simultaneously. From a geometrical point of view, the global tilt is the sum of the pelvic tilt (PT) and the C7 vertical tilt (angular value of sagittal vertical axis). The aim of this study is to evaluate the global tilt with comparison to PT and sagittal vertical axis (SVA), with the hypothesis that GT would be the least sensitive to positional changes. METHODS: A cohort of 22 patients with sagittal malalignment was identified from a multicentric database of adult spinal deformities (ASD). Inclusion criteria were age >30 years, SVA > 40 mm and/or PT > 20°. All patients had full spine EOS radiographs in positions 1 and 2 (P1 and P2), in which the patient was asked to stand and put his hands on his shoulders without any effort (P1), or to make an effort to be as straight as possible (P2). PT, SVA and GT were measured in both positions and changes between P1 and P2 were calculated and compared using Student's t test with significance level at p < 0.05. RESULTS: No significant changes were observed for GT; SVA and PT were significantly influenced by patient positioning. SVA decreased and PT increased for all cases in P2 whereas the changes in GT were in either direction. The average increase in PT was 7.1° (±5.4) or 30.8 % (±24.9); decrease in SVA was 45.1 mm (±25.6) or 60.0 % (±44.2) while the change in GT was 4.4° (±3.3) or 12.6 % (±9.3). DISCUSSION: GT appears to be less affected by the patient's position compared to SVA and PT. This seems logical because GT contains both spinal alignment and pelvic compensation; it is not affected by their changes in opposing directions. CONCLUSION: GT appears to be the most reliable single sagittal plane parameter in ASD. It is the least affected by patient position and incorporates both the pelvic and the spinal alignment within one measure.

[Congenital malformations of the growing spine : When should treatment be conservative and when should it be surgical?]. / Kongenitale Fehlbildungen der Wirbelsäule im Wachstum : Wann konservativ behandeln, wann operativ?

Congenital malformations of the spine are caused by genetic and teratogenic factors. By means of asymmetrical longitudinal growth of the spine they can lead to deformity, most commonly to scoliosis. The malformations can be classified as failure of formation, failure of segmentation and mixed-type malformations. The extent of the deformity and its progression are determined by the remaining growth potential and the location and type of malformation. Up to one third of such deformities are associated with some sort of cardiac or urogenital malformation. The treatment concept is typically determined on an individual basis. Mild deformities often remain undetected. Conservative treatment using a brace has no substantial effect on the primary curve but might be helpful in the treatment of long sweeping, flexible, secondary curves. If rapid progression is documented or expected, surgical intervention as early as possible is warranted to prevent secondary structural changes. The surgical treatment should be focused on and limited to the site of malformation. The aim of surgery is the correction of the deformity at the site of asymmetrical growth. This can be achieved either by resection of a hemivertebra or by performing a vertebral column resection or other type of osteotomy. If notable compensatory, secondary curves are present, these can be corrected with growing rod constructs. The aim of all types of treatment is the correction of existing deformity or the prevention of its progression, in order to ensure balanced growth of the healthy regions of the spine. The present paper discusses the conservative and surgical treatment modalities available to achieve these aims.

The Core Outcome Measures Index (COMI) is a responsive instrument for assessing the outcome of treatment for adult spinal deformity.

INTRODUCTION: The Core Outcome Measures Index for the back (COMI-back) is a very brief instrument for assessing the main outcomes of importance to patients with back problems (pain, function, symptom-specific well-being, quality of life, disability). However, it might be expected to be less responsive than a disease-specific instrument when evaluating specific pathologies. In patients with adult spinal deformity, we compared the performance of COMI-back with the widely accepted SRS-22 questionnaire. METHODS: At baseline and 12 months after non-operative (N = 121) and surgical (N = 83) treatment, patients (175 F, 29 M) completed the following: COMI-back, SRS-22, Oswestry Disability Index (ODI) and SF-36 PCS. At 12 months' follow-up, patients also indicated on a 15-point Global Rating of Change Scale (GRCS) how their back problem had changed relative to 1 year ago. Construct validity for the COMI-back was assessed by the correlation between its scores and those of the comparator instruments; responsiveness was assessed with receiver operating characteristics (ROC) analysis of COMI-back change scores versus the criterion 'treatment success' (dichotomized GRCS). RESULTS: Baseline values for the COMI-back showed significant (p < 0.0001) correlations with SRS-22 (r = -0.85), ODI (r = 0.83), and SF-36 PCS (r = -0.82) scores; significantly worse scores for all measures were recorded in the surgical group. The correlation between the change scores (baseline to 12 months) for COMI and SRS-22 was 0.74, and between each of these change scores and the external criterion of treatment success were: COMI-back, r = 0.58; SRS-22, r = -0.58 (each p < 0.0001). The ROC areas under the curve for the COMI-back and SRS-22 change scores were 0.79 and 0.82, respectively. CONCLUSION: Both baseline and change scores for the COMI-back correlated strongly with those of the SRS-22, and differed significantly in surgical and non-operative patients, suggesting good construct validity. With the "change in the back problem" serving as external criterion, COMI-back showed similar external responsiveness to SRS-22. The COMI-back was well able to detect important change. Coupled with its brevity, which minimizes patient burden, these favourable psychometric properties suggest the COMI-back is a suitable instrument for use in registries and can serve as a valid instrument in clinical studies emerging from such data pools.

Influence of gender on patient-oriented outcomes in spine surgery.

PURPOSE: Few studies have examined gender differences in patient-oriented health-related quality of life before and after spine surgery. This study examined the influence of gender on baseline status and 1-year postoperative outcomes in a large series of patients undergoing surgery for different degenerative spinal disorders. METHODS: The study included 1518 patients [812 men and 706 women; mean (SD) age 61.4 ± 16.2 years], with three different pathologies (disc herniation, degenerative spondylolisthesis, or spinal stenosis), treated with specified surgical approaches. Preoperatively and 12 months postoperatively, patients completed the multidimensional Core Outcome Measures Index (COMI). Medical history, surgical details and perioperative complications were documented with the Eurospine "Spine Tango" Surgery 2006 form. RESULTS: Preoperatively and for all three pathologies, women had significantly (p < 0.05) worse COMI-scores than men, especially for the sub-domains "leg/buttock pain", "dominant pain intensity", and "general quality of life"; the change in the COMI sum score 12 months postoperatively showed no significant gender differences for any pathology (p > 0.05). 71.3 % males and 72.9 % females achieved the minimal clinically important change score (MCIC; 2.2 point reduction) for the COMI. Controlling for potential cofounders (preoperative COMI, ASA, complications, pathology), gender showed no significant association with the failure to achieve MCIC. CONCLUSIONS: This results show that women do not differ significantly from men regarding their postoperative outcome, even though they present with a worse preoperative status. The management of a patient's condition should not differ depending on their gender, since both men and women are able to improve to a similar extent.

Validity of a single-item measure to assess leg or back pain as the predominant symptom in patients with degenerative disorders of the lumbar spine.

PURPOSE: Recent studies suggest that the location of predominant pain (back or leg) can be a significant predictor of the outcome of surgery for degenerative spinal disorders. However, others challenge the notion that the predominant symptom can be reliably identified. This study examined the validity of a single item used to determine the most troublesome symptom. METHODS: A total of 2,778 patients with degenerative disorders of the lumbar spine scheduled for surgery with the goal of pain relief completed a questionnaire enquiring as to their most troublesome symptom ["main symptom"; back pain (BACK) or leg/buttock pain (LEG)]. They also completed separate 0-10 graphic rating scales for back pain (LBP) and leg/buttock pain (LP) intensity. Receiver operating characteristics (ROC) analysis was used to determine the accuracy with which the "LP minus LBP" score was able to classify patients into their declared "main symptom" group. Sub-studies evaluated the test-retest reliability of the patients' self-rated pain scores (N = 45) and the agreement between the main symptom declared by the patient in the questionnaire and that documented by the surgeon after the clinical consultation (N = 118). RESULTS: Test-retest reliability of the back and leg pain scores was good (ICC2,1 of 0.8 for each), as was patient-surgeon agreement regarding the main symptom (BACK or LEG) (κ value 0.79). In the BACK group, the mean values for pain intensity were 7.3 ± 2.0 (LBP) and 5.2 ± 2.9 (LP); in the LEG group, they were 4.3 ± 2.9 (LBP) and 7.5 ± 1.9 (LP). The area under the curve for the ROC was 0.95 (95 % CI 0.94-0.95), indicating excellent discrimination between the BACK and LEG groups based on the "LP minus LBP" scores. A cutoff score >0.0 for "LP minus LBP" score gave optimal sensitivity and specificity for indicating membership of the LEG group (sensitivity 79.1%, specificity 95.7%). CONCLUSIONS: The responses on the single item for the "main symptom" were in good agreement with the differential ratings on the 0-10 pain scales for LBP and LP intensity. The cutoff >0 for "LP minus LBP" for classifying patients as LEG pain predominant seemed appropriate and suggests good concurrent validity for the single-item measure. The single item may be of use in sub-grouping patients with the same disorder (e.g. spondylolisthesis) or as an indication in surgical decision-making.

The influence of comorbidity on the risks and benefits of spine surgery for degenerative lumbar disorders.

PURPOSE: The ageing of the population will see a growing number of patients presenting for spine surgery with appropriate indications but numerous medical comorbidities. This complicates decision-making, requiring that the likely benefit of surgery (outcome) be carefully weighed up against the potential risk (complications). We assessed the influence of comorbidity on the risks and benefits of spine surgery. METHODS: 3,549/4,053 patients with degenerative lumbar disorders, undergoing surgery with the goal of pain relief, completed the multidimensional Core Outcome Measures Index (COMI; scored 0-10) before and 12 months after surgery. At 12 months postoperatively, they also rated the global treatment outcome and their satisfaction with care. Using the Eurospine Spine Tango Registry, surgeons documented surgical details, American Society of Anesthesiologists comorbidity (ASA) grades and perioperative surgical and general complications. RESULTS: 29.0% patients were rated as ASA1 (normal healthy), 45.7% as ASA2 (mild/moderate systemic disease), 24.9% as ASA3 (severe), and just 0.4% as ASA4 (life-threatening). In going from ASA1 to ASA3 (ASA4 group too small), surgical complications increased significantly from 5.0 to 14.5% and general complications increased from 2.9 to 15.7%; 12-month outcomes showed a corresponding decline, with a good global outcome being reported by 79% ASA1 patients, 76% ASA2, and 68% ASA3. Satisfaction with treatment was 87, 85, and 79%, respectively, and reduction in COMI was 4.2 ± 2.9, 3.7 ± 3.0, and 3.4 ± 3.0 points, respectively. Multiple regression analysis revealed a significant (p < 0.0001) independent effect of ASA grade on both complications and outcome. CONCLUSION: The negative impact of comorbidity on the outcome of spine surgery has not been well investigated/quantified to date. The ASA grade may be helpful in producing algorithms for decision-making and preoperative counselling regarding the corresponding risks and benefits of surgery.

Posterior vertebral column resection in early onset spinal deformities.

PURPOSE: Early onset spinal deformities (EOSD) can be life-threatening in very young children. In the growing spine, surgical intervention is often unavoidable and should be carried out as soon as possible. A deformed section of the spine not only affects the development of the remaining healthy spine, but also that of the chest wall (which influences pulmonary function), the extremities and body balance. Posterior vertebral column resection (PVCR) represents an effective surgical solution to address such problems. However, reports in the literature concerning PVCR are mostly limited to its use in adolescents or adults. The purpose of this study was to illustrate our experience with PVCR in EOSD and to describe the surgical technique with respect to the unique anatomy of young children. MATERIALS AND METHODS: Four children [mean age 3.7 (range 2.5-5.2) years] with severe spinal deformity underwent PVCR through a single approach. Multimodal intraoperative monitoring was used in all cases. Surgery included one stage posterior circumferential resection of one vertebral body along with the adjoining intervertebral discs and removal of all posterior elements. A transpedicular screw-rod system was used for correction and stabilisation. Fusion was strictly limited to the resection site, allowing for later conversion into a growing rod construct at the remaining spine, if necessary. Relevant data were extracted retrospectively from patient charts and long spine radiographs. RESULTS: The mean operation time was 500 (range 463-541) min, with an estimated blood loss of 762 (range 600-1,050) ml. Mean follow-up time was 6.3 (range 3.5-12.4) years. After PVCR, the mean Cobb angle for scoliosis was reduced from 69° (range 50-99°) to 29° (5-44°) and the sagittal curvature (kyphosis) from 126° (87-151°) to 61° (47-75°). The mean correction of scoliosis was 57 % (18-92°) and of kyphosis, 51 % (44-62°). There were no spinal cord-related complications. In three patients, spinal instrumentation for growth guidance (fusion less growing rod technique) was applied. Two patients had complications: one patient had a complication of anesthesia, halo pin failure, and revision surgery with extension of the instrumentation cranially due to loss of correction; the second patient had a postoperative infection, which required plastic reconstructive measures. CONCLUSION: PVCR appears to be an effective technique to treat severe EOSD. There are important differences in its use in young children when compared with older patients. In patients with EOSD, additional surgical procedures are often necessary during growth, and hence non-fusion instrumentation beyond the vertebral resection site is advantageous, as it permits spinal growth and the later addition of fusion.

[Tumors and metastases of the upper cervical spine (C0-2). A special challenge]. / Tumoren und Metastasen der oberen Halswirbelsäule (C0-2). Eine besondere Herausforderung.

Tumors of the upper cervical spine are rare and represent less than 0.5 % of all spinal tumors. The types of tumor and the clinical presentation are as varied as the modalities used for treatment. The unique anatomy of the upper cervical spine with its high physical mobility means that biomechanical considerations and neighboring anatomical structures (e.g. vertebral artery, medulla oblongata, lower cranial nerves and pharynx) must be considered when creating a treatment plan. Finding a balance between complete tumor removal, the preservation and reestablishment of stability and function and the possible necessity for postoperative radiotherapy is of utmost importance and must be assessed on an individual basis. In this review paper some important points will be presented concerning the preparation of the patient, the planning of the operation and the surgical approach used in treating tumors of the craniocervical junction.