The Spine Journal 7 (2007) 263–265

Editorial

SPORT and the Canadian ExperienceCharles Fisher, MD, MHSc(Epi), FRCSC, Paul Bishop, DC, MD, PhD*

Combined Neurosurgical and Orthopaedic Spine Program, Vancouver Hospital and Health Sciences Centre, Department of Orthopaedics, University of

British Columbia, D6 Heather Pavilion, 2733 Heather Street, Vancouver, British Columbia, V5Z 3J5, Canada

The first published studies of the Spine Patient Out-comes Research Trial (SPORT) have reported results fromthe treatment of patients with sciatica secondary to lumbardisc herniation [1,2]. The publication of additional SPORTstudies concerning treatment outcomes for patients withother common spinal disorders is pending. These resultshave been eagerly awaited based on the study’s peer reviewgrant funding, level one methodology, and anticipateddefinitive answers to questions concerning the optimaltreatment for lumbar disk herniation causing sciatica.Although the study does not disappoint in its overall con-duct, relatively little has been added to the evidence-basedcare of this condition. What is evident is the extreme diffi-culty in performing a randomized controlled trial (RCT) ina surgical setting despite adequate funding, ample epidemi-ologic expertise, and principled investigators who havechampioned the cause for evidence-based care of spine

Charles Fisher, MD, MHSc (Epi), FRCSC

* Corresponding author. D6 Heather Pavilion, 2733 Heather

Street, Vancouver General Hospital, Vancouver, BC, V5Z 3J5, Canada.

Tel.: þ(604) 875-4549; fax: þ(604) 875-585.

E-mail address: paul.bishop@vch.ca (P. Bishop)

1529-9430/07/$ – see front matter � 2007 Elsevier Inc. All rights reserved.

doi:10.1016/j.spinee.2007.03.001

patients over the last 2 decades. Part of this difficulty is alsobecause of America’s heath-care system, which is charac-terized by often highly informed patients who are moreor less free to choose the treatment they prefer in a highlycompetitive setting.

These initial studies represent a significant undertakingwith the enrollment of over 1,200 patients and the collec-tion of data from 13 locations across the United States.The methodology was designed to provide a comparisonof outcomes of nonoperative care with surgical manage-ment by using the gold standard RCT study design. Ina unique, but unconventional maneuver, a prospective ob-servational cohort of patients who chose not to participatein the RCT was added. Thus, selection bias from a patientpreference perspective was clearly established. Despite thisoption, 747 of 1,991 eligible patients (38%) refused to par-ticipate in either design. This is a significant proportion, yetthere is no description of the demographics and other per-tinent baseline variables of this patient group to determineif they were unique compared with the enrolled patients. Ina total studied cohort of 1,244 patients, only 501 (25% ofthe original patients eligible) agreed to be randomized,whereas the majority (743) preferred to make their own

Paul Bishop, DC, MD, PhD

264 C. Fisher and P. Bishop / The Spine Journal 7 (2007) 263–265

treatment choice. Although the demographic and some ofthe baseline variables are similar between the groups (wedo not know about the cohort who did not participate),the SF-36 (bodily pain and physical function scores) andOswestry scores were not, with the more severely affectedpatients choosing the surgical arm of the prospective cohortdesign. It would appear that patient preference trumps ex-tensive evidence-based informed consent to the patientsin the health-care system used in this study. Would other in-dustrialized nations with more limited surgical resourcesface similar recruitment issues?

Although selection bias predominates the limitations ofthese studies, other issues are worthy of comment. Thestated inclusion criteria required sciatica symptoms fora minimum of 6 weeks but did not set any upper limit onduration of symptoms. As a result, a component of chronicsciatica patients was likely included, and the potential com-plications associated with a chronic pain patient populationwere not excluded. Although the chronic pain confoundershould have been dealt with by randomization, this may wellhave not been the case in the observational trial. Given that ithas been previously reported that surgery early in the clinicalcourse is associated with better results, the outcomes of thepatients choosing surgery may have been skewed [3,4].

Logistics and systematic evidence necessitated the non-operative arm of these studies to be termed ‘‘usual care.’’Although there was no current gold standard for nonopera-tive care at the design stage of the SPORT study, some ad-vances have been recently reported. Image-guided selectivenerve root steroid injections have been shown to be effec-tive in enabling recovery [5], and this benefit has shownto be greatest at 2 weeks after the onset of sciatica [6]. Only43% and 38% of the patients in the nonoperative treatmentarms received a spinal injection, and the injections givenwere characterized generally as ‘‘epidural injection(s).’’Furthermore, the point in the patient’s clinical course thata spinal injection was administered was not reported ineither SPORT paper, and the percentage of patients who re-ceived image-guided selective nerve root steroid injectionsrather than the less effective epidural steroid injections [7–10] was not made clear.

The results of the SPORT randomized and observationalstudies showed statistically equivalent and significantly bet-ter outcomes, respectively, for patients undergoing surgerywhen compared with those who received nonoperative care.In the randomized trial, intent to treat analysis of the datawas used. This protects against selection bias and biases to-ward the null hypothesis. Therefore, if a significant differ-ence is detected, it is a very robust conclusion. In theSPORT study, there was a crossover rate of 40% and45% in the surgical and nonoperative groups, respectively.Crossover rates in both directions of this magnitude go be-yond the boundaries of an intent-to-treat analysis, and theconclusion of equivalence between the 2 forms of treatmentis probably not justified. This is supported by the very sig-nificant differences between surgery and nonoperative care

when analyzed in an ‘‘as-treated manner.’’ This is an effi-cacy approach but is justified with crossovers of suchmagnitude in both directions. Again, patient preferenceprevails.

Closer scrutiny of the protocols of the RCT and cohortstudies offers another possible explanation for this differ-ence of significance. The surgical treatment arms of thetwo studies differed significantly in that 91% of the patientsin the observational study received surgery within 6 weeksof enrollment, whereas only 32% received surgery at 6weeks in the randomized trial. Thus, to some degree, thetwo studies also compared the outcomes associated with‘‘early’’ and ‘‘late’’ surgery. It is also interesting to note thatthe results of the observational trial showed that a surpris-ingly large number of patients (70%) assessed in the differ-ent regions of the United States chose surgery. Given thatpatients with chronic sciatica were not excluded, it is uncer-tain how many of these patients had already failed a courseof nonoperative treatment. The study describes the charac-teristics of these patients, and variables such as socio-economic status, societal conditions, and severity ofsymptoms all play a role (patient preference again). Lastly,the reason for choosing not to compare the SF-36 outcomedata to normative data and thereby not providing insight onoverall patient recovery is not made clear by the authors.For these reasons, the degree to which the results of theSPORT studies can be applied to the general populationof patients with acute sciatica within and outside of theUnited States is uncertain.

The SPORT study discusses many of the limitations in-herent within their study. They compare with previous stud-ies to document external validity, which is solid, but this isclearly at the cost of internal validity, specifically selectionbias. The results are similar to these studies and support thepremise that in the surgical realm perhaps prospective co-hort studies provide better evidence from a generalizabilityperspective because of the limitations inherent within a sur-gical RCT, especially in the United States. In 2000, a large-scale, prospective observational trial comparing surgicaland nonoperative care of patients with acute sciatica sec-ondary to herniated nucleus pulposus was initiated in theCombined Neurosurgical and Orthopaedic Spine Program(CNOSP) in Vancouver, Canada. Canada’s universalhealth-care system ensures equal care and access for all pa-tients; however, access is delayed and patients are given lit-tle choice in their care provider. In the CNOSP study, allpatients were initially evaluated in a bidisciplinary clinicby one of eight spine surgeons and one of three nonsurgicalback care physicians. The study was conducted over a pe-riod of 4 years, enrolled over 600 patients, and has beenby far the largest clinical trial involving the treatment ofpatients with acute sciatica completed outside the UnitedStates [11,12].

The CNOSP study was a single-center study with theNeurologic Symptom Scale (NSS) from the NASS LumbarSpine Instrument as its primary outcome. The disease-

265C. Fisher and P. Bishop / The Spine Journal 7 (2007) 263–265

specific NASS lumbar spine instrument and the SF-36scores were recorded at the time of the initial visit as wellas at 6 and 12 months after baseline (nonoperative) andafter the date of surgery. Multivariate analysis was usedto adjust the statistical results for known confoundinginfluences. Surgery consisted of a standard lumbar micro-discectomy, and nonoperative care was performed accord-ing to the North American Spine Society’s Phase IIIclinical guidelines for multidisciplinary specialists on her-niated lumbar discs. None of the patients included in thisstudy received any form of spinal injection because itwas not readily available in our center at that time.

The key findings of the CNOSP trial were that, althoughsurgical intervention showed a statistically significantgreater improvement, it did not produce a clinically signif-icant greater improvement when compared with nonopera-tive care in NASS or SF-36 scores at either the 6- or12-month point. (Only four patients crossed over from thenonoperative group and received surgery). These resultsare therefore in variance with those of the observationalSPORT study and the Maine Study. However, in makingsuch a comparison, it should be noted that the majority ofthe patients in the CNOSP study had longer symptom dura-tion before intervention, reflecting the Canadian HealthCare System. Second, neither the patients who received sur-gery or nonoperative care had their SF-36 scores return tonormative levels at the 12-month follow-up point, suggest-ing that neither form of treatment is able to completelyalleviate all of the disability that is associated with this ail-ment at 1 year after intervention [10].

The main goal of the major clinical trials published todate [1–4,12] comparing surgical and nonoperative carefor these patients must surely have been to help clarify clin-ical decision making. It is questionable whether or not thisgoal has been achieved. SPORT has shown us that surgeryis safe, and all of these studies have shown us that patientswith more severe symptoms who choose surgery do betterthan patients with nonoperative care, but on a more levelplaying field and over time, the interventions have a similareffect. Furthermore, it would appear that therapeutic inter-vention is just one of many variables that influence choiceand eventual outcome, thus supporting the generalizabilityafforded by a well-controlled prospective cohort study inclinical conditions amenable to operative or nonoperativecare. Perhaps the most valuable lessons to be learned hereare that despite an all-star cast, adequate funding, anda level 1 design, clinical trials of this nature have inherentlimitations and that the precision of the research question,

the choice of the research methodology, the health-care en-vironment, and the variable of patient preference can havea major influence on the outcome. Hence, this is the reasonwhy ‘‘evidence-based medicine’’ is not just a RCT.

Whether or not any further clinical trials are warranted isopen for debate. Perhaps a shift in the research paradigmintegrating basic science research strategies directed towardmediating the inflammatory nature of acute sciatica withclinical trials using specific nonoperative interventions isindicated. Finally, more questions around therapeutictiming, the economic implications, and the contributionof patient preference seem to be the germane questions inthe new era of minimally invasive interventions and highlyinformed patients.

References

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