Factor analysis of the North American Spine Society outcome assessment instrument: a study based on a spine registry of patients treated with lumbar and cervical disc arthroplasty

Background contextStudies involving factor analysis (FA) of the items in the North American Spine Society (NASS) outcome assessment instrument have revealed inconsistent factor structures for the individual items.PurposeThis study examined whether the factor structure of the NASS varied in relation to the severity of the back/neck problem and differed from that originally recommended by the developers of the questionnaire, by analyzing data before and after surgery in a large series of patients undergoing lumbar or cervical disc arthroplasty.Study design/settingProspective multicenter observational case series.Patient sampleThree hundred ninety-one patients with low back pain and 553 patients with neck pain completed questionnaires preoperatively and again at 3 to 6 and 12 months follow-ups (FUs), in connection with the SWISSspine disc arthroplasty registry.Outcome measuresNorth American Spine Society outcome assessment instrument.MethodsFirst, an exploratory FA without a priori assumptions and subsequently a confirmatory FA were performed on the 17 items of the NASS-lumbar and 19 items of the NASS-cervical collected at each assessment time point. The item-loading invariance was tested in the German version of the questionnaire for baseline and FU.ResultsBoth NASS-lumbar and NASS-cervical factor structures differed between baseline and postoperative data sets. The confirmatory analysis and item-loading invariance showed better fit for a three-factor (3F) structure for NASS-lumbar, containing items on “disability,” “back pain,” and “radiating pain, numbness, and weakness (leg/foot)” and for a 5F structure for NASS-cervical including disability, “neck pain,” “radiating pain and numbness (arm/hand),” “weakness (arm/hand),” and “motor deficit (legs).”ConclusionsThe best-fitting factor structure at both baseline and FU was selected for both the lumbar- and cervical-NASS questionnaires. It differed from that proposed by the originators of the NASS instruments. Although the NASS questionnaire represents a valid outcome measure for degenerative spine diseases, it is able to distinguish among all major symptom domains (factors) in patients undergoing lumbar and cervical disc arthroplasty; overall, the item structure could be improved. Any potential revision of the NASS should consider its factorial structure; factorial invariance over time should be aimed for, to allow for more precise interpretations of treatment success.     

Cross-cultural adaptation of the lumbar North American Spine Society questionnaire for Italian-speaking patients with lumbar spinal disease

STUDY DESIGN: A cross-cultural adaptation and cross-sectional study of a sample of lumbar spine patients, with a subsample followed prospectively for retest reliability. OBJECTIVES: To assess the Italian version instrument reliability and validity. SUMMARY OF BACKGROUND DATA: The orthopaedic outcome measurements have been usually focused on objective parameters as radiograph measures or other technical aspects. However, these parameters are weakly related with outcomes that are more relevant to patients as functional status and symptoms. In the last ten years, the patient-oriented measures have become an important aspect of spinal clinical outcome evaluation. The most common instruments to assess patient perspective are self-administered questionnaires that must be validated by a widely accepted process to evaluate reliability and validity, which are fundamental for every instrumental measure. METHODS: The North American Spine Society (NASS) questionnaire was culturally adapted for Italian-speaking people following the Guillemin criteria. The Italian version was tested on 74 consecutive patients who were referred to the authors' department and suffered from low back pain with leg irradiation. The results were compared with other validated patient-oriented measures. Forty-eight-hour retests were performed on a subsample of 45 patients. RESULTS: The questionnaire was favorably accepted by patients. The lumbar spine pain and disability and neurogenic symptoms subscales showed a high correlation with other patient-oriented measures, as hypothesized, and it also showed good values on test-retest. CONCLUSIONS: The questionnaire should be considered for patient health status monitoring and for clinical trials.     

Evaluation of the North American Spine Society Instrument for assessment of health status in patients with chronic backache

PURPOSE OF THE STUDY: The translation/back and translation and validation of the North American Spine Society (NASS) Instrument in German was published recently. This contribution aims at describing the scoring of this questionnaire. METHOD: The scoring is oriented on the recommendations of the developing scientists of the US-American original, with whom we cooperated during the German validation. RESULTS: The scoring algorithm is described, a program for computerized scoring in SPSS was written. Program syntax and the questionnaire are reproduced. CONCLUSION: The contribution enables interested researchers to apply and score the NASS questionnaire in German-speaking countries.     

Validation of the North American Spine Society Instrument for assessment of health status in patients with chronic backache]

BACKGROUND: Pain and functional limitations are the chief symptoms in patients with back pain. However, standardized assessment of these domains are still not commonplace in clinical practice. The objective of this study was the cultural adaptation and validation of the North American Spine Society (NASS) Lumbar Spine Outcome Assessment Instrument for German speaking patients with back pain. METHODS: Translation and backtranslation of the NASS instrument was performed according to international recommendations. 56 consecutive inpatients with a confirmed diagnosis of dorsopathia completed a German version of the NASS instrument, the SF-36 and an established German instrument for back patients (FFbH-R). All patients completed the questionnaires 48 hours apart to assess test-retest reliability. Validity was assessed through correlation with corresponding subscales of the SF-36, the FFbH-R and a 0-10 pain numeric rating scale. Internal consistency and item-to-scale correlation served as statistics of reliability. RESULTS: The two subscales of the NASS Instrument for cervical and lumbar problems correlate significantly with the corresponding subscales of the FFbH-R and the SF-36 (r = 0.28-0.83, p < 0.05) and 0.39-0.68 (p < 0.05) with a pain numeric rating scale. Test-retest reliability demonstrated intraclass correlation coefficients between 0.82 to 0.89. CONCLUSION: The German version of the NASS Cervical and Lumbar Spine Outcome Assessment Instrument allows the standardized assessment of pain, functional limitations and neurogenic symptoms in patients with back pain and the international comparison of health states and therapeutic outcomes.     

Conflict of interest and professional medical associations: the North American Spine Society experience

Background contextRecently the financial relationships between industry and professional medical associations have come under increased scrutiny because of the concern that industry ties may create real or perceived conflicts of interest. Professional medical associations pursue public advocacy as well as promote medical education, develop clinical practice guidelines, fund research, and regulate professional conduct. Therefore, the conflicts of interest of a professional medical association and its leadership can have more far-reaching effects on patient care than those of an individual physician.PurposeFew if any professional medical associations have reported their experience with implementing strict divestment and disclosure policies, and among the policies that have been issued, there is little uniformity. We describe the experience of the North American Spine Society (NASS) in implementing comprehensive conflicts of interest policies.Study designA special feature article.MethodsWe discuss financial conflicts of interest as they apply to professional medical associations rather than to individual physicians. We describe the current policies of disclosure and divestment adopted by the NASS and how these policies have evolved, been refined, and have had no detrimental impact on membership, attendance at annual meetings, finances, or leadership recruitment. No funding was received for this work. The authors report no potential conflict-of-interest-associated biases in the text.ResultsThe NASS has shown that a professional medical association can manage its financial relationships with industry in a manner that minimizes influence and bias.ConclusionsThe NASS experience can provide a template for other professional medical associations to help manage their own possible conflicts of interest issues.     

Outcome sensitivity of the North American Spine Society Instrument with special consideration for the neurogenic symptoms of chronic back pain

BACKGROUND: Back pain is one of the most common chronic diseases in developed countries. The related enormous direct and indirect costs demand evidence-based decisions on rehabilitative care. Our study is intended to evaluate the two NASS outcome dimensions pain and neurological symptoms regarding their sensitivity to change within an inpatient rehabilitation scheme for chronic back pain. METHODS: The study observed a cohort of consecutive patients for one year (n = 70). By applying two outcomes instruments which are in common use internationally (SF-36 and NASS) it enhances comparability with other studies. Moreover the FFbH-R was applied for cross validation. RESULTS: On discharge from hospital an improvement of physical and emotional health as well as pain reduction were found. The results of the various instruments are consistent and support each other and suggest sensitivity to change of the NASS instrument regarding its pain and neurology subdimensions. CONCLUSION: The NASS outcome instrument monitors well the established therapeutic effects of chronic back pain inpatient rehabilitation schemes in the short run and in the long run over a twelve-month period following hospital discharge.     

Artificial intervertebral discs and beyond: a North American Spine Society Annual Meeting symposium.

BACKGROUND CONTENT: This is a synopsis of a symposium presented to the North American Spine Society Annual Meeting in Seattle, WA, 2001. PURPOSE: To bring to the reader who may not have attended the symposium a distillation of the material presented on this frontier of spinal surgery. METHODS: Panel presentation. RESULTS: The proposed indication for artificial disc replacement is a degenerated but contained disc, painful to the point of major life-style interruption, refractory to at least 1 year of nonoperative treatment, preferably at a single lumbar level and without infection, listhesis or major facet joint disease or spinal stenosis. Total disc replacements have been developed and used mostly in Europe. Disc nucleus replacements have also been developed. No disc replacement has been approved for general use in North America as yet. The US Food and Drug Administration is conducting investigational device exemption studies at this time. CONCLUSIONS: Artificial disc replacement is not a new concept, the first attempts having been done in the early 1950s. During the past 15 years, considerable advance has been made with large numbers of patients, mostly in Europe, having surgery with either total disc prostheses or disc nucleus replacements. Only with truly scientific studies using patient randomization, pre- and postsurgery outcome analyses by unbiased independent observers and statistical analysis by independent experts will the real value of these devices be realized.     

Neurological outcome after surgery for thoracic and lumbar spine injuries

Summary New techniques for internal fixation, employed by neurosurgeons and orthopaedic surgeons, provide reduction and stabilization with early mobilization of patients after injuries of the thoracolumbar spine. It has, however, appeared difficult to prove that the neurological outcome after surgery may be superior to conservative treatment.In this study the neurological results after surgery are evaluated in 30 patients with injuries of the spinal cord and/or cauda equina. Canal encroachment was found on tomograms or CT in all patients. The unstable fractures, dislocations or fracture-dislocations were all reduced and stabilized by the Harrington distraction device. However, peroperative inspection revealed that the Harrington instrumentation alone may be inadequate in achieving intraspinal decompression. Additional anterior decompression by posterolateral approach was necessary in 13 of the 30 patients (43%). In this series there was an unexpectedly high rate of dural tears. These were found in 8 patients (27%) and nerve roots (cauda equina) appeared to have herniated through the tear in 6 of the 8 patients. Significant improvement of the neurological deficit was obtained in 22 of the 30 patients (73%), and the improvement rate in patients with incomplete lesions of the spinal cord was 83% (25 of 30 patients). In this series there was a definite trend toward greater neurological recovery when compared to the results obtained in patients treated conservatively.The importance of a neurosurgical approach in diagnosis and treatment of these patients is stressed.     

单节段微创经椎间孔腰椎椎体间融合内固定治疗腰椎滑脱症的效果

目的:评价单节段微创经椎间孔腰椎椎体间融合(minimally invasive transforaminal lumbar interbodyfusion,MiTLIF)内固定治疗腰椎滑脱症的临床效果。方法:2007年1月~2010年3月163例腰椎滑脱症患者接受单节段MiTLIF和内固定治疗。男61例,女102例;年龄37～72岁,平均51.6岁。退变性腰椎滑脱97例,峡部裂性腰椎滑脱66例;Ⅰ度滑脱135例,Ⅱ度28例;L3滑脱7例,L4 86例,L5 70例。采用经最长肌和多裂肌间隙入路,可扩张工作通道置于关节突上,行MiTLIF和经皮椎弓根螺钉固定。将163例患者按时间顺序依次分为A组(第1~55例)、B组(第56~110例)和C组(第111~163例),统计手术时间、术中X线暴露时间、术中和术后出血量及并发症发生情况,并进行组间比较。采用腰痛视觉模拟评分(VAS)和功能障碍指数(ODI)评分评估临床效果,腰椎薄层CT扫描重建评价椎间融合情况。结果:163例术中出血100～750ml,平均330ml;术后出血10～175ml,平均57ml;手术时间83～230min,平均145min;术中X线暴露时间27～126s,平均59s。B组术中出血量和X线暴露时间与A组比较及C组手术时间、X线暴露时间、术中和术后出血量与A组比较均明显减少(P<0.05);C组手术时间、术中X线暴露时间、术中和术后出血量与B组比较亦明显减少(P<0.05)。7例术中硬膜囊撕裂,其中A组4例,B组2例,C组1例,均在术后第2天出现脑脊液漏,经对症处理术后5d内脑脊液漏停止。4例术后出现新的神经根损害表现,均为A组病例,通过内窥镜下减压和神经根松解后神经根损害症状消失。91例患者获得10～47个月随访,平均24.5个月。术前、术后3d及末次随访腰痛VAS评分分别为6.8±2.4分、1.5±0.6分和0.8±0.4分,术后3d及末次随访与术前比较有显著性差异(P<0.05)。术前及末次随访ODI评分分别为39.4±5.1分和11.3±2.6分,差异有显著性(P<0.05)。末次随访椎间融合率为96.7%(88/91)。结论:采用单节段MiTLIF和经皮椎弓根螺钉固定治疗Ⅰ度、Ⅱ度腰椎滑脱症安全有效。