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Contemporary Management of Symptomatic Lumbar Disc Herniations

Kolawole A. Jegede, Anthony Ndu, Jonathan N. Grauer

pages 217-224

Abstract | Full Text | Full-Text PDF (109 K

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Contemporary Management of Symptomatic Lumbar Disc Herniations

Kolawole A. Jegede, BS, Anthony Ndu, MD, Jonathan N. Grauer, MD

Lumbar disc herniations are common clinical entities that may

cause lumbar-related symptoms. The spectrum of treatment options is geared toward a patient's clinical presentation and ranges from nothing to surgical intervention. Many lumbar disc herniations cause no significant symptoms. In studies of asymptomatic individuals who have never experienced lumbar-related symptoms, 30% have been reported to have major abnormality

on magnetic resonance imaging. The mainstay of treatment of

patients with symptomatic disc herniations is accepted to be nonoperative (as long as there are no acute or progressive neurologic deficits); this includes medications, physical therapy, and

potentially lumbar injection. For patients with symptomatic disc herniations who fail to respond appropriately to conservative

measures, surgical intervention may be considered. For this population, lumbar discectomy is considered to be a good option.

目前对有症状的腰椎间盘突出的治疗

Contemporary Management of Symptomatic Lumbar Disc Herniations

Kolawole A. Jegede, BS, Anthony Ndu, MD, Jonathan N. Grauer, MD*

Lumbar disc herniations are common clinical entities that may

cause lumbar-related symptoms. The spectrum of treatment options is geared toward a patient’s clinical presentation and ranges from nothing to surgical intervention. Many lumbar disc herniations cause no significant symptoms. In studies of asymptomatic individuals who have never experienced lumbar-related symptoms, 30% have been reported to have major abnormality

on magnetic resonance imaging.1 The main stay of treatment

of patients with symptomatic disc herniations is accepted to be nonoperative (as long as there are no acute or progressive neurologic deficits); this includes medications, physical therapy,

and potentially lumbar injection. 2–4 For patients with symptomatic disc herniations who fail to respond appropriately to con

servative measures, surgical intervention may be considered. For this population, lumbar discectomy is considered to be a good option.

腰椎间盘突出是导致腰椎症状的常见的临床疾病。根据患者的临床描述，其治疗范围从无需处理到需要手术干预。许多腰椎间盘突出没有明显症状，对那些从来没有过腰椎症状的无症状个体的研究表明，30%被报道存在显著的磁共振改变。有椎间盘突出症状的患者的治疗主要还是非手术治疗为主（除非出现急性的或者进展性的神经症状），包括药物、理疗、注射治疗等等。有症状的腰椎间盘突出患者，经非手术治疗无效，才会考虑手术，对于这类患者来说，腰椎间盘摘除术是一个不错的选择。

LUMBAR DISCECTOMY

腰椎间盘摘除术

Discectomy is the most common operation performed in the United States for patients who are experiencing lumbar-related symptoms.5 Nonetheless, despite the wide acceptance of discectomy as a treatment option for symptomatic lumbar disc herniation, there has been a paucity of level I evidence supporting the effectiveness of this surgery compared with nonoperative care.6 Significant regional variation in discectomy rates in the United States and lower international rates have also raised questions about when these surgeries should be performed.7

椎间盘摘除术是美国腰椎症状患者最常见的手术方式。尽管椎间盘摘除术被广泛认为是有症状腰椎间盘突出的手术方式之一，但是仍然缺乏一级证据证明其比非手术治疗更加有效。美国国内不同区域显著不同的手术率，以及较低的国际手术率也同样产生这样的问题，到底何时应该手术。

Several studies have compared surgical and nonoperative treatment, but small sample sizes, study design limitations, and failure to plan for high crossover rates limit the strength of these studies. Between the years of 1983 and 2007 there were 4 randomized controlled trials (RCTs) comparing operative care with more conservative management, not including the well-publicized Spine Patient Outcomes Research Trial (SPORT).5,8–12

几个研究比较了手术和非手术治疗，但是样本量低、研究设计限制和难以控制的高交叉率使得这些研究缺乏效力。1983年至2007年之间有四个随机对照试验研究了手术治疗和保守治疗的差异，这其中没有包含总所周知的脊柱患者预后研究实验（SPORT）。

Weber9 performed a controlled, prospective study with 10 years of follow-up. Of the 280 patients enrolled in this study, 126

were randomized to either surgery or physical therapy. The others were not randomized and had surgery or nonoperative treatment. The group randomized to surgery had statistically better outcomes after 1 year. After 4 years, however, although the

surgery outcomes were still better, this difference was no longer statistically significant.

Weber进行了一组随访达10年的前瞻性对照研究，研究包含280名患者，其中126名被随机分配进行了手术或者理疗，其余患者未进行随机分组，接受了手术或者是理疗。随机分组中的手术组在1年随访时预后优于保守组，这一点具有统计学意义。但是在4年后，尽管手术组仍然有优势，但是这种差别不存在统计学意义了。

Buttermann12 conducted a prospective, randomized study comparing epidural steroid injection (ESI) with discectomy for treatment of lumbar disc herniation. One hundred patients who had failed noninvasive therapy for 6 weeks were randomly assigned to receive ESI or discectomy. This study found that discectomy patients had more rapid improvement in their symptoms. The investigators stated that ESI was not as effective as surgery in reducing symptoms in those with large herniations.

Buttermann进行了一项前瞻性随机研究来比较硬膜囊外类固醇注射（ESI）与椎间盘摘除术治疗腰椎间盘突出的效果。100名经非侵入性治疗6周无效的患者被随机分配，进行硬膜囊外类固醇注射和椎间盘摘除术治疗。该研究发现椎间盘摘除术的患者症状消失较快。研究者认为在治疗较大椎间盘突出的患者时，ESI治疗效果不如手术。

Osterman and colleagues8 conducted a prospective, randomized study comparing physical therapy with discectomy for treatme

nt of lumber disc herniation. Fifty-six patients who had radiating back pain below the knee for 6 to 12 weeks were randomized to receive either isometric physical therapy or discectomy. Patients were followed for 2 years and at final follow-up the study found no clinically significant difference between the groups in terms of leg pain intensity and other secondary outcomes.

These investigators proposed discectomy provided only some short-term benefit.

Osterman及同事进行了一项前瞻性随机研究比较理疗和椎间盘摘除术。56名有持续超过6到12周的膝关节以下后侧放射痛的患者被随机分组进行了等量理疗或者椎间盘摘除术，所有患者随访2年，最后的随访结果表明在下肢疼痛程度和其他继发症状方面，两个组之间区别不存在统计学差别。他们认为椎间盘摘除术只提供了短期的疗效。

Another study by Peul and colleagues11 was a prospective, randomized study comparing nonsurgical treatment with discectomy for the treatment of lumbar disc herniation. Two hundred and eighty subjects were followed for a year and the investigators found that the 2 groups had similar outcomes at 1 year, but those who underwent surgery had faster rates of recovery and self-perceived pain.

Peul及同事的另外一项前瞻性随机研究比较了非手术治疗和椎间盘摘除术在治疗椎间盘突出方面的效果。对208名患者进行了一年的随

访，结果表明预后差别不大，但是手术组恢复速度和自省疼痛更快。

These studies together contribute significant information about

the outcomes that can be expected from lumbar discectomy. For an outcome measure, Weber9 used a patient-described 4-tier descriptive scale (poor, fair, good, excellent). The 3 other more recently published studies by Osterman and colleagues, 8

Peul and colleagues, 13 and Butterman12 used more common

general and disease-specific health quality surveys, and clinical

examination. Each of these studies had 1 year follow-up, except for Weber’s, in which long-term follow-up to 10 years after surgery was included.

这些研究都说明要椎间盘摘除术预后还是值得期待的。在评价预后方面，Weber使用了患者描述4级评分法（差、一般、好、很好）。其他三个较近期研究，Ostermann及其同事、Peul及其同事、Butterman他们使用了更加通用更具备疾病特异性的健康质量调查方法和临床体检。除了Weber的研究有术后10年的随访以外，其他每一种研究的随访为1年。

Crossover rates were an issue for each of these RCTs. The crossover from nonsurgical treatment group to the surgical treatment group ranged from 34.7%9 to 54%,12 with the average being 42.6%. In each of these studies, a smaller number of patients crossed over from the surgical treatment group to the no

nsurgical treatment group, with an average of 21.4%.10

交叉率是这些随机对照实验的共同问题。这些非手术治疗和手术治疗组的交叉率为34.7%到54%，平均42.6%。每一组研究中都有一小部分患者从手术组交叉至非手术组，平均21.4%。

Two of the 4 studies used an intent-to-treat (ITT) analysis. 8,9 Weber used an ITT analysis but also used tables to show the treatment assigned and the treatment received. However, in the primary analysis these investigators left out the 34.7% of patients who crossed over to the surgical group. Osterman and

colleagues used an ITT and an as-treated analysis but the as-treated analysis was not reported in detail.

4个研究中有2个使用了意向性分析（ITT）。Weber使用了这种方法，也使用了表格来显示分配的和选择的治疗方式。但是基本分析中这些研究者忽略了34.7%的患者交叉到了手术组。Osterman及其同事使用了ITT分析和拟治疗分析，但是后者报道中未详细说明

The results of these lumbar disc herniation RCTs were variable when compared with each other. The general observed trend

was that early outcomes were improved with surgical intervention, but longer-term outcomes were more similar when comparing nonoperative and surgical management.

这些腰椎间盘突出的随机对照试验的结果互相都不相同，大体的趋势是经过手术干预，早期的预后比较好，但是远期预后和非手术组基本

相同。

SPORT TRIAL

脊柱患者预后研究实验

The SPORT trial was a federally funded, multicenter, prospective, randomized, controlled study assessing the efficacy of surgery versus nonsurgical treatment of lumbar intervertebral disc herniation. This large undertaking took more than 7 years to complete and was published in the Journal of the American Medical Association in 2006. 5 Despite the tremendous amount of

work and resources that were put into this research study, the primary investigators were unable to make a definitive statement about the advantage of any 1 treatment type, largely because of issues with study group crossover.5,14

SPORT实验是全联邦的多中心、前瞻性、随机对照研究，它用于评价手术和非手术在治疗腰椎间盘突出的效果。这项巨大的工作历时7年完成，发表在2006年的美国医学学会杂志。除了研究中投入的巨大的工作量和资源，主要的研究者们无法明确哪种治疗方法的是更好，这大部分原因是由于研究组之间的交叉。

The main goal of this trial was to evaluate the efficacy of surgery versus nonoperative treatment of lumbar disc herniation. Patients were enrolled over a 4-year period from 13 multidisciplinary spine clinics in 11 US states. Investigators screened 2720

patients and 1991 were found eligible. Of these 1991 patients, 1244 enrolled in the trial, 501 agreeing to be randomized, and 743 enrolled in an observational arm of the study. 15 The primary outcomes measures used in this study were changes in the Medical Outcomes Study Health Survey bodily pain and physical function scales and the modified Oswestry Disability Index for a 2-year period.

这项实验的主要目的是评价手术和非手术在治疗腰椎间盘突出的效果。研究历时4年包含了美国11个州的13个多学科脊柱治疗中心的患者。研究者们筛查了2720名患者，其中1991名患者合格。这些合格的1991名患者中，1244名加入了实验，501名同意进行随意分配，743名成为实验的观察部分。研究中对预后的基本评估方法是在医学预后研究健康调查身体疼痛和物理功能评分，以及修改版Oswestry伤残指数ODI在两年期间的改变。

The study reported that the ITT analysis showed significant improvement in all measured outcomes in both treatment groups. The investigators concluded by stating that because of high crossover rates from both groups, no direct comparison between surgical and nonsurgical management was warranted based on the ITT analysis.5 The a priori null hypothesis of no difference between surgical and nonsurgical treatments was thus unable to be ruled out.14,16

研究报道意向性分析显示两个组的预后都显著改善。研究者们推断认为由于两个组的高交叉率，两个组之间没有基于意向性分析的直接比较，因此，之前的手术组和非手术组之间不存在差别的零假设不能排除。

The issues noted with this high-profile study have led to much scrutiny. 8,16–18 Despite a clear statement by the study investigators that direct comparisons between the 2 treatments would not be valid, many have interpreted the results to suggest equivalence between surgery and nonsurgical care for patients with lumbar disc herniations.5 The error in these statements

was most likely caused by the reader interpreting the treatment groups in the SPORT trial as the treatment received. However, because of the ITT analysis and a high crossover rate, the

nonoperative group contained many patients who did have surgery. The surgical benefits for those patients who crossed over into the surgery treatment group were allocated to nonoperative care and clearly biased the results toward the null hypothesis.14

这项备受瞩目的研究招致很多审查。除了研究者们明确声明两个组之间的直接比较无效，许多人认为其结果意味着手术和非手术治疗在椎间盘突出的治疗作用是相同的。这些错误大部分是由于读者认为SPORT实验中的治疗组就是患者接受的治疗。但是由于意向性分析和高

交叉率的存在，非手术组中仍然有很多患者接受了手术，对于这些患者来说，手术效果却计入非手术治疗中，因此使结果偏移向了之前的零假设。

SPORT STUDY HYPOTHESIS

脊柱患者预后研究实验 研究假设

The formation of a reasonable and clinical relevant study hypothesis is extremely important for the success of a prospective, randomized clinical trial. 19 The only hypothesis that can be assessed by this type of study is one that is stated before the study takes place. The stated a priori hypothesis of the SPORT

study was simply to determine if there was no difference between surgical and nonsurgical management in patients with lumbar disc herniations. The dichotomous hypothesis was intended to give an answer to whether surgery was superior to nonoperative care.

一个合理的临床研究中相关的假设的形成是前瞻性随机临床试验成功的关键。这种研究能评估的唯一的假设就是研究开始时提出的。本SPORT研究开始之前的假设仅仅是简单区别手术和非手术对治疗腰椎间盘突出是否存在差异，分支假设是判断两种治疗方式哪一种更好。

This simplified hypothesis proved problematic in many ways. The stated hypothesis implied that lumbar disc herniation is a u

niform condition, with surgery and nonoperative care as the competing treatments. 10 In current practice, surgical and nonsurgical treatments for lumbar disc herniations are not thought of as competing or transposable options but rather treatments along a spectrum of care. Further, lumbar disc herniation is a heterogeneous condition with differences in pain severity, neurologic impairment, natural history, and treatment response.14

很多方面说明这种简单假设是存在问题的。折个假设中暗示腰椎间盘突出是唯一条件，而手术和非手术是竞争性的治疗。实际情况中，手术和非手术并非竞争性的治疗，而是治疗的一个的不同阶段。更深一点说，腰椎间盘突出本身是一个多样性的条件，其疼痛程度、神经损害程度、病史、治疗反应都不相同。

The main goals in treatment of patients presenting with this heterogeneous condition are alleviating pain and returning function with as little risk as possible.20–22 Hence, almost all patients who present with painful lumbar disc herniation without acute or progressive neurologic deficit begin treatment with nonsurgical approaches. Most surgeons would be hesitant to offer surgical treatment to a patient who has pain for a short duration or who is actively improving. This situation makes it difficult to randomize patients to one of these otherwise staged treatment options.14,22

各种不同条件的患者治疗的目的都是减轻疼痛和恢复功能，并且风险要尽可能小。因此，几乎所有那些没有急性或者严重的神经症状的腰椎间盘突出患者，最初都选择非手术治疗。大多数外科医生都会犹豫是否给一个疼痛时间不长或者有显著改善的患者进行手术。这些使得将患者随机分组十分困难。

SPORT STUDY POPULATION

SPORT 研究样本量

Randomization to surgical versus nonsurgical treatments is challenging. Based on this, despite multiple centers collecting patients over a significant period of time, it is difficult to fully power a study. This complication has contributed to concern that the SPORT study could have inadvertently biased toward the null

hypothesis14 and may have created a situation in which the study would fail to recognize a difference between surgical and

nonsurgical treatment groups when one exists (type II error).

随机进行手术或者非手术治疗是十分具有挑战性的。基于这个原因，尽管多中心通过长时间收集了大量的患者，仍然不够支持这项研究。这种困境使大家关注到这项研究也许本身无意的更偏向零假设，因此使它难于认识到手术和非手术治疗本身存在的差异（二型错误）。

As mentioned earlier, patients presenting with symptomatic lumbar disc herniation would likely initially be treated with nonsurgical management. Those who were presenting with mild or imp

roving symptoms would continue treatment with less invasive

measures. Almost 20% of patients randomized to receive surgery in the RCT group had self-reported mild/moderate symptoms that were improving.15 There is class II evidence that patients with mild symptoms who undergo surgery usually do not have a significant treatment benefit compared with nonsurgical treatment. 21 In current clinical practice these patients may not

have undergone surgery. However, whether or not the 20% of mildly affected patients in the RCT crossed over to nonoperative treatment or had surgery, their treatment response to surgery would be associated with the surgical group. The inclusion

of this patient population underestimated the effects of surgery in the study compared with what would be encountered in clinical practice.

像早先说到的，腰椎间盘突出的患者早期愿意接受非手术治疗。那些疼痛轻微或者症状有改善的患者会继续接受较少侵入性治疗。随机对照试验的手术组患者中20%自我报告有轻度或者中度症状的得到了改善。有2级证据表明，那些症状轻微的患者经过手术治疗后，其效果并不比非手术治疗更显著。现在的临床中，对这些患者也许不会进行手术。但是，不论是否在这个随机对照试验中，这些有20%的症状较轻的患者交叉入非手术组，或者他们确实进行了手术，他们对治疗的反应都被计算入手术组。与临床中实际情况相比，这种数量的包

含使得手术效果对研究的影响力被低估。

The underestimation of the benefits of surgery also holds true

for severely symptomatic patients assigned to the nonsurgical treatment group. Severely affected patients are known to receive the highest benefit from surgery21 and many of the patients assigned to the nonsurgical group crossed over in this study.

All the benefits associated with surgery as a result of this high crossover were credited to the nonsurgical treatment group because of the ITT analysis. In both instances the effect was to underestimate the advantages of surgery and overestimate the advantages of nonsurgical management in relation to what would occur in current clinical practice.

这种对手术效果的低估同样发生在对那些症状严重而被分配到非手术组的患者身上。众所周知，重症患者手术效果更佳，本研究中，有很多非手术组的患者交叉入手术组而进行了手术。由于意向性分析，这种高交叉率使得手术的效果被统计入了非手术组。根据临床实践，两种情况都使得手术的优势被低估，而非手术治疗的效果被夸大。

Because surgery is known to benefit those with severe symptoms, and in the current study patients identified to have severe symptoms were less likely to enroll in the SPORT RCT, this would also have the effect of underestimating the effects of surgery in relation to what would be observed in current clinical

practice. Analyzing the observational cohort population in SPORT shows that 75% of these patients had severe symptoms, which was significantly worse than the average symptom severity

in the RCT population, and they chose to undergo surgery.15

The other 25% of this cohort was made up of patients with mild disease who mostly initially chose nonsurgical treatment. Patients who had severe symptoms were more likely to refuse to

enter the randomization group and again this underestimated the effects of surgery. The overall effect of 3 of 4 patients choosing not to be randomized causes further underestimation of the true benefit of surgery within the SPORT RCT compared with what would be seen in current clinical practice.5,14

众所周知手术对那些症状严重的患者效果更好，本研究中症状严重的患者很少可能进入SPORT随机对照研究实验，这同样低估了手术在临床上将来可能产生的效果。分析SPORT的观测人群发现75%的患者症状比随机对照试验中的平均症状严重程度还严重，他们选择手术。其余25%的患者由那些症状较轻的患者组成，这些患者初期多数选择非手术治疗。症状严重的患者大多拒绝被随机分配，这又一次使得手术的效果被低估。与我们将在临床实践中看到的相比较，SPORT随机对照试验中，四分之三的拒绝被随机分配的患者导致了远期低估真正的手术效果。

HIGH CROSSOVER RATE

高交叉率

With a power of 0.85 the authors expected to see a 10-point

difference in the surveys of patient health with the sample size chosen. However, based on the literature on lumbar disc herniation, a significant crossover rate should have been expected.8,9,11–13 The large crossover rate causesa reduction in the difference observed between the 2 treatment groups. Patients with severe symptoms assigned to nonsurgical treatment were more likely to cross over to the surgery group, whereas patients

with mild symptoms assigned to the surgical group were likely

to cross over to the nonsurgical group.

研究者们期望从现有数量患者健康的调查中发现显著的差距，期望这些研究具有85%的影响力。但是基于这些腰椎间盘突出的文献，交叉率可能相当高。这些高交叉率导致了两组之间差别的减少。被分配入非手术组的严重症状患者很可能交叉入手术组，而手术组的症状较轻的患者又可能选择进入非手术组。

This high crossover rate significantly decreased the power of the study and hence the ability of the study to detect any difference between the treatments groups, even if one existed. The failure of the investigators to include any crossover rate in their study design or power calculation severely weakened SPORT. With a crossover rate around 45% in the SPORT RCT the e

ffective power of the study was only 7%, compared with the 85% reported.14 The clinical appropriateness and cost-effectiveness of this study may have been questioned if any consideration of crossover were made before the study began.

高交叉率显著的降低了研究的效力，从而降低其发现差别的能力，即使这种差别存在。研究者们没能够考虑这种交叉率和效力计算，这严重的削弱了SPORT。45%的交叉率的SPORT随机对照试验其影响力只有7%，而不是85%。如果研究开始之前就能考虑到交叉率，这项研究的临床适当性和效能就可能会被质疑。

NO STRATIFICATION OF KNOWN PROGNOSTIC FACTORS

未对已知预兆因素分层

Early studies have found a strong correlation between pretreatment symptom severity and treatment outcomes in regards to

lumbar disc herniation. The Main Lumbar Spine Study21 showed that patients who reported serious neurologic symptoms had better response to surgery than nonoperative management that was clinically and statistically significant. Surgery was found

to be less effective compared with nonsurgical treatment in those who presented with mild symptoms. The intensity of presenting symptoms was an available prognostic factor but is difficult to control for in an RCT.

早期研究发现，腰椎间盘突出治疗前症状的严重程度与治疗效果具有

很强的交互联系。主要腰椎研究MLSS表明具有严重神经症状的患者对手术治疗反应比非手术治疗要好，这一点在临床上和统计学上都具有重要意义。对那些症状较轻的患者，手术比非手术的效果要差。症状表现程度是一个可知的预兆因素，但是它在随机对照试验中难以控制。

The inability to stratify by these and other prognostic factors and instead blindly randomize patients may decrease the clinical relevance of a study and make data difficult to interpret. The randomization without thought of the prognostic factors masks the beneficial effects of surgery in patients with severe symptoms by combining them with patients with mild symptoms, who are known not to benefit from more invasive procedures.

由于无法对这些预兆因素分层，而盲目的对患者随机分组将降低临床研究的相关性，使得其结果难以解释。不考虑预兆因素的随机化使得手术对重症患者和轻症患者的效果混为一谈，众所周知后者不接受侵入性治疗。

DISCUSSION讨论

RCTs are considered to be the most powerful studies in medical literature.23,24 Such studies lead to what is referred to as level I evidence and usually command great respect from the scientific community. However, the difficulties faced by SPORT and the other RCT discussed reveal that there are limitations to

such studies. 25,26

随机对照试验被认为是医学文献中最有效力的研究。这些研究产生了一级证据因而长收到学术界的重视。但是，上面所说的SPORT和其他RCT面对的困难揭示了这些研究的局限性。

RCTs that attempt to compare surgical versus nonsurgical treatments are particularly difficult to design and perform. 10 Patient compliance, randomization, and blinding investigators and patients are challenging or impossible. Further, varying severity of presenting symptoms affects the treatment options and treatment response. 5

用于比较手术和非手术的随机对照实验非常难以设计和实施。患者依从性、随机化、双盲原则都难以贯彻甚至不可能。更深远点说，症状不同严重程度也影响了治疗选择和治疗反应。

The goal of the investigators of SPORT and the other RCTs investigating lumbar disc herniations was to take the results from their representative sample population and to generalize them to anyone with lumbar disc herniation. This is a challenging objective. Not only were the patients already those presenting for surgical evaluation, but those who agree to enroll in RCTs may be different from those who refuse to participate.

研究者们的SPORT和RCT研究调查腰椎间盘突出，想将他们的具有代表性的小样本量的结果放大到所有腰椎间盘突出患者，这是一个难

以达到的目标。不仅仅是这些已经准备要手术的患者，还包括那些愿意加入RCT的患者也与那些不愿加入的也存在不同。

The investigators compared the RCT patient cohort with the nonrandomized observational cohort.15 Although the study reported no statistically significant differences between the 2 groups, a closer look revealed substantial differences in measurements of pain, disability, and perceptions of their own health state.

The observational group was essentially divided into 2 distinct

populations composed mostly of those with severe symptoms that were significantly worse than the average seen in the RCT cohort. The differences seen in these groups could have significantly affected the response treatment. It could also be assumed that similar differences could have been noted in the 719 patients who refused to participate in the study completely. That there are substantial differences between those who decide to participate in a randomized clinical trial and those who do not shows that any results reported may not be generalizable to the population.

研究者们比较了RCT患者和非随机的观察组患者。尽管研究报道这两组之间不存在统计学差别，更进一步的观察揭示，他们在疼痛的测量、致残、自我健康的认知情况都存在不同。被分为两个明显的群的观察组大多数是由那些症状明显比RCT平均水平更严重的患者组成。

也可以假设，那些719名没有加入研究的患者中间同样存在这种差别。愿意加入实验和不愿意加入实验的患者之间这种本质的区别就说明研究的任何结果都无法放大到整个人群。

ITT analysis is the statistical tool that protects randomization.

Use of ITT analysis makes the assumption that the treatment that the patient initially assigned is the treatment that the patient received at some time point. 27 As the rate of crossover increases, the effects of randomization diminish. Crossover from

treatment groups decreases the only desired difference that the investigators would want to see between the Jegede et al 222randomly assigned groups, which is the treatment that is received.

意向性分析是统计学的工具，它保护了随机化。意向性分析使我们假设患者分配接受的治疗就是他实际接受的治疗。当交叉产生时，随机化就失去了作用。治疗组的交叉降低了研究者们想看到的区别，他们想看到随机组之间的区别，而这是患者接受的治疗。

If no crossover occurs between 2 randomly assigned treatment groups then the assumed difference in outcome can be validly related to the treatment received. On the other hand, if half

the patients in a particular treatment group cross over into the opposite group it will be impossible to detect a difference. It

is not surprising that Weinstein and colleagues5 reported no di

fference between treatments, with more than 40% of patients

crossing over at the 2-year time point.

如果不存在交叉，那么先前假设的两个组之间的差别，也就是治疗方式与预后相关的差别，是有效的。另一方面，如果一个组中有一半患者交叉入另一个组，那么这种差别无法查出。所以，当两组之间存在40%的交叉率时，Weinstein和他的同事会报道两组之间无差别。

SPORT was 1 of the few RCTs assessing the benefits of surgery in lumbar disc herniation to state an a priori power calculation but did not take into account the crossover rate that ended up being observed. The investigators stated that with a power of 0.85 they would expect to see a 10-point difference in the 36-item Short Form Health Survey (SF-36) scale used and a

similar effect size in the Oswestry Disability Index with the sample size they chose.5 This calculation was assuming that there would be a 100% compliance with the assigned treatment.

When taking into account the crossover rate seen in the SPORT trial, the power of the study was calculated to be 0.07.14 If the investigators had assumed a crossover rate of at least 25%based on prior studies9,12 the power of the SPORT RCT would still be only0.32.14

SPORT是很少几个评估手术对腰椎间盘突出效果的随机对照试验之一，它声明一种先验力计算，但是没考虑到后来观察到的交叉率。研

究者们声明85%的效力他们期望看到SF36表和Oswestry伤残指数上10分的区别。这个计算假设患者有100%的依从性。当考虑到交叉率时，研究的效力降低到7%。如果研究者们曾经根据之前的研究，假设交叉率至少有25%的话，那么这个SPORT RCT的效率将会只有32%。

Despite the efforts of a large multicenter RCT, SPORT was unable to provide valid data on the effect size of the 2 treatments studied, because the crossover rates were so high. Because

of this crossover rate and many other factors, the power that is usually associated with RCTs was lost in this study. Despite the overwhelming preference given to RCTs there is no clear statement that observational studies and RCTs produce consistently dissimilar results. 25,26 All the RCTs of lumbar disc herniation treatment performed over the last 2 decades consistently had high crossover rates and were not able to definitively answer important questions about patient care.10 These recurring issues raise the question if it is possible to conduct a valid and

quality RCT of treatment outcomes for lumbar disc herniation

(Table 1).

由于交叉率如此之高，除开大的多中心的随机对照试验的努力，SPORT仍不能提供研究中两种治疗的有效的数据。由于这种交叉率和很

多其他因素，本应和随机对照试验研究一起的效力在本研究中失去了。尽管研究者们如此偏爱随机对照试验，但是仍然缺乏文献表明随机对照试验和观察性研究存在不同的结果。过去20年里，所有的腰椎间盘突出的随机对照试验中治疗方式都存在高交叉率，因而不能明确回答治疗患者方面的重要问题。这些反复的文献提出这样一个问题：是否能够奢以一个有效的高质量的随机对照试验来判断腰椎间盘突出的治疗效果。