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Comparative effectiveness research in spine surgery Degenerative spine disorders are a significant cause of patient morbidity and are a prominent factor in healthcare costs in many countries. Pressure for healthcare cost control and the desire for improved outcomes have led to an expanding emphasis on evidence-based medicine methodologies in spine research. Determination of the optimal treatment paradigm for many common degenerative spinal disorders has proven difficult and comparative effectiveness research is increasingly being employed to examine these clinical dilemmas. The Swedish Spine Registry and the Registry of the Scoliosis Research Society are two of the long-standing databases compiling data for spine patients. Spine surgery professional organizations have recently taken a prominent role in assembling procedural- and diagnosis-based registries, specifically addressing therapeutic outcomes for spine patients. As healthcare systems continue to evolve, comparative effectiveness research driven by spine registries may better elucidate the appropriate clinical choices for patients with these challenging illnesses.

Wendell B Lake1, Nathaniel P Brooks1 & Daniel K Resnick*1 University of Wisconsin School of Medicine & Public Health, Department of Neurological Surgery, Madison, WI, USA *Author for correspondence: Tel.: +1 608 263 9585 Fax: +1 608 263 6901 [email protected] 1

KEYWORDS: comparative effectiveness research n outcome measures n registry n spine n surgery

Spine disorders are a significant driver of healthcare costs, with the total expenditure of spine-related procedures in the USA estimated to be tens of billions of dollars [1,2]. Recent enactment of the US healthcare legislation and scrutiny of the costs associated with spine surgery have led to increased prominence of comparative effectiveness research (CER) in the spine. Since 2008, publications of spine CER have increased [3]. Physicians are critically appraising available evidence in the spine literature to determine its usefulness in guiding clinical decision-making. Professional organizations have aided in this effort by preparing clinical guidelines that describe the strength of evidence supporting various treatment options [4,5]. Professional organizations working in the field of spine disorders have recognized that many deficits exist in the evidence currently available for treatment strategies. The quality of data generated and its applicability to specific patients has been variable. Randomized controlled trials (RCTs) have been performed to evaluate the effectiveness of spine procedures in defined patient populations [6,7]. RCTs, when properly performed, are often regarded as the highest quality medical evidence. Spine surgery, when compared with other fields, has published fewer randomized controlled studies and those that have been performed have major limitations. The SPORT RCT, for example, has been criticized for extensive crossover. In addition, some of these studies have narrow inclusion and exclusion criteria that make it difficult to generalize to a broader population. Significant obstacles exist for performing high-quality RCTs for spine disease, including blinding, cost, patient-selection bias, ethical concerns in some cases, patient expectations and established prior practice patterns [4,6,8]. Of course the goal of CER is not to eliminate RCTs, but to synthesize these data with data from other sources in an effort to improve clinical decision-making.

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Proponents of CER indicate that rigid adherence to a hierarchy of evidence (e.g., stating that RCTs are always superior to cohorts) may stifle the ability of clinicians to accumulate data. CER uses evidence from medical literature to rigorously compare existing treatments in an effort to determine the optimal treatment for an illness. The definition of ‘optimal’ may vary depending upon the patient or payer perspective. Some have pointed out that CER could be used in some situations to limit access to care if the payers found that a therapy, while beneficial to the patient, fell below a rigidly prescribed cost–effectiveness threshold set by the payer [9]. In most CER literature, the emphasis is on evaluating real-world effectiveness of treatment, as opposed to drawing inferences from narrowly defined patient populations that may not accurately ref lect the actual target patient population [10]. The American Reinvestment and Recovery Act of 2009 allocated US$1.1  billion towards CER. A 15-member council for the coordination of CER was established by this legislation. All members of this council are government employees and only half are required to have clinical experience [9]. Given the recent growth in interventional spine procedures, the geographical variation in spine care and the associated growing cost, the Institute of Medicine has made it a priority to compare operative and nonoperative therapies for spine patients [10–13]. Given the difficulty of performing relevant RCTs for spine patients, some have advocated patient registries as a way to evaluate the comparative effectiveness of therapies. Therefore, interest in developing and maintaining registries has been rekindled, allowing practitioners to longitudinally follow larger patient populations over time. Purported benefits of patient registries include that they allow long-term follow-up of actual patient populations treated with established practice patterns. These characteristics lend strong external validity to registry data as compared with RCTs. Proponents of evidence obtained from patient registries assert that these data may be quite robust and generalizable. Registries may serve to complement RCTs when available or provide useful evidence when they are absent [14]. Data collected from spine patient registries will likely form the future basis of CER. The purpose of this review is to describe the development of spine registries, including their

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design, and to provide some current examples of spine registries along with a description of the data collected by each. The review also discusses the ongoing challenges and unmet needs in this field. Concluding the paper, a description of the possible future directions that CER in the spine may take is provided. Examples of registries

Sweden was early to establish registries to monitor long-term outcomes in patients with various spine conditions [15,16]. Outcome data from the Swedish registry are available since 1987. Sweden has compiled patient data since 1964, but all of the hospitals only began participating in 1984. Now with all of the hospitals participating, it is possible to analyze medical records for a nation of approximately 9  million people. Initially, a general patient database was generated for all types of medical conditions. Data included were not specific to spine disorders and included information such as International Classification of Diseases revision 9 (ICD-9) code, date of operation, date of admission and date of discharge. The country also has a death registry and this could be used to obtain mortality information, such as the number of patients who died within 30 days of undergoing lumbar discectomy and the cause of death. Using data from this general medical database, one study analyzed the outcome from 27,576 operations for herniated disks performed between 1987 and 1999. The rate of reoperation for this group was 5% at 1  year and 10% at 10  years. Approximately 14.7% of patients required readmission to the hospital for some spine-related symptom. The risk of mortality within 30  days of the operation was 0.5 per 1000 operations compared with 2.9  per 1000 operations for total hip replacements (although the average age of patients undergoing disk surgery was 42 years compared with approximately 62 years for patients undergoing hip replacement). In this review, death was very uncommon in patients undergoing lumbar disk surgery, and as a cause of death, cardiac causes were most common followed by accident or suicide [15]. In analyzing 9664 operations, the reoperation rate was 1% at 1 year and 11% at 10 years. There were 3.5 deaths per 1000 operations within the first 30 days postoperation. The higher rate of mortality for patients with spinal stenosis, as compared to those with lumbar disk herniation

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alone, was ascribed to the stenosis patients being older (by 20 years on average) [16]. In a later study from the Swedish register, smokers were found to have less improvement in symptoms compared with nonsmokers [17]. In Sweden, the need to evaluate the comparative effectiveness of treatments lead to the genesis of the Swedish Spine Register. This registry achieved widespread use and started collecting national data in 1998, and was one of the first comprehensive spine registers specifically oriented towards spine patients. The decision to focus on degenerative lumbar spine disorders was made owing to the heterogeneity of treatment, along with the rapidly advancing number of new procedures and technologies available for treating these disorders. Variation of the surgical decision-making process in degenerative spine disorders, in comparison to infectious or traumatic disorders, was ascribed to the fact that the surgical indication for these disorders is a subjective symptom – pain – compared with the more objective findings associated with trauma or infection. The Swedish Spine Register initially had the goal of tracking procedure trends and outcomes for lumbar degenerative disease, but was expanded to include cervical spine disorders, infections, deformity, tumor and traumatic injuries of the spine. A variety of validated instruments were used including the EuroQol questionnaire (EQD), Oswestry Disability Index (OWD) and Short form 36 questionnaire (SF-36), to make subjective outcomes more objective. Initial data collected for Swedish spine patients included diagnoses, procedure type and date, admission date and discharge date. The registry gradually evolved to collect data more specific to spine disease, including quality of life measures, social history, smoking status and work status [17–22]. The Swedish Spine Registry is diagnosis based and compares outcomes for patients treated for a specific pathology. In spine pathology management, options generally include physical therapy, manipulation, medications and surgery. If a registry is designed as a diagnosis-based registry, it can provide information on all management options for a given spine condition. The design of a registry is critical in determining its usefulness. In designing a registry it is critical for the investigators to decide what questions they would like to answer from data collected from the spine registry.

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Increasing the amount of data collected can reduce compliance in a patient-based registry and may make the registry more cumbersome to maintain, but it also increases the data available for comparing various factors. In developing the Swedish Spine Registry, there were several iterations of design, but in the end investigators settled on a diagnosis-based registry that emphasized the comparison of operative and various nonoperative therapeutic strategies. It did require a period of time to reach its final form, and it eventually collected a variety of data including, social history components, and it used validated instruments, such as the Oswestry Disability questionnaire, the EuroQol questionnaire version 5D (EQ-5D) and the SF-36, in an effort to quantify treatment outcomes. Regardless of the specific data collected, these investigators and others who have worked towards developing registries have found that certain characteristics are necessary to create a successful registry. At a minimum these include buy-in by all of the healthcare practitioners, patient-based documentation and sufficient financial support [21,23,24]. Two prominent spine registries in Europe include the Swiss Spine Registry and the Spine Tango Registry. The Swiss Spine Registry has followed disc replacement patients and kyphoplasty patients. The Spine Tango Registry, organized by the Eurospine Organization, is the first international registry effort and evaluates surgical and conservative management of spine disease [25,101]. For lumbar disc replacement and anterior lumbar interbody fusion data has been compared between the Swiss Spine Registry and the Spine Tango Registry [26]. As the emphasis on comparative effectiveness has increased, registries have been created that collect data for US spine patients. Since the healthcare system in the USA differs in many ways compared with the systems in other countries, collecting data in this environment has created unique challenges and opportunities. As in Sweden, professional societies have served as an organizing force for creating North American spine registries. The largest professional organizations in neurosurgery, the American Association of Neurological Surgeons and the Congress of Neurological Surgeons, have both created registries to collect data for patients with spine disease. An interdisciplinary group combining both orthopedic and neurological spine

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surgeons has also begun to create a similar data collection platform [3,27]. In addition, some have proposed more regional databases, such as the Wisconsin Spine Outcomes Group (WISPOG), that will incorporate all spine surgeons from a specific large geographical region. Some of these proposed registries are procedurally based, such as the Neurosurgery Patient Outcomes in Treating Spinal Disorders register, which is collecting functional, economic and complication data related to lumbar microdiskectomy and singlelevel fusion procedures. Others, such as the WISPOG proposed by the senior author, and implemented in pilot form thus far, will be diagnosis based and address a variety of degenerative spine conditions, the majority of which will be treated in the community

by nonoperative intervention. Similar to the Swedish Spine Registry, WISPOG is a diagnosis-based registry collecting patient entered data, including information from validated instruments such as the Oswestry Disability Index, the Visual Analog Scale and the SF-36. Thus far, these databases have been accruing data rapidly, with an 80% compliance rate in the case of WISPOG [28]. Table 1 provides a synopsis of various spine registries including their organizing entities, the type of registry, outcomes measures employed, patient characteristics and limitations [102–106]. Ongoing challenges

From the preceding discussions, it is apparent that CER in spine care is at an immature stage and despite making progress in recent years,

Table 1. Characteristics of various spine registries. Registry

Responsible organization

SweSpine

Type

Outcomes data

Patients included

Limitations

Swedish Society Diagnosis of Spinal based Surgeons

VAS, ODI, SF-36 and EQ-5D

Nationwide in Sweden; 75% of all spine patients are entered into the registry Data are available of tens of thousands of patients, includes patients 16 years or older

Addresses a relatively homogenous group of patients in a country with strong financial resources and a centralized healthcare system Limited follow-up data are available

NEUROPOINT AANS/Congress Procedure SD of Neurological based Surgeons

VAS, ODI and SF-36

Currently, 200 patients are enrolled at various centers throughout the USA Includes adult patients undergoing lumbar microdiskectomy or lumbar fusion for spondylolisthesis

Procedural database currently represents a limited number of centers and is only examining lumbar fusion and lumbar microdiskectomy

N2QOD

AANS/Congress Procedure of Neurological based Surgeons

ODI and EQ-5D

A multicenter registry that will enroll lumbar microdiscectomy and singlelevel lumbar fusion patients

Procedural database, began enrolling in February 2012, limited participation at this time

Scoliosis Research Society Database

Scoliosis Research Society

Diagnosis based

ODI, SF-12 and Cobb angle

Patients aged 20 years or younger with idiopathic scoliosis At present tens of thousands of patients have been enrolled

Relatively narrow focus, does not include patients with coexisting neuromuscular disease or patients who have had an operation prior to being entered into the database

NASS Spine Registry

North American Diagnosis Spine Society based

ODI, VAS and SF-36

Patients older than 18 years with The pilot version of the registry will be lumbar degenerative disease are opened in July 2012 enrolled at multiple centers Initial participation will be limited Includes orthopedic and neurosurgery centers

WISPOS

UW-Madison Spine Surgery

VAS, ODI and SF-36

Adult patients with degenerative lumbar disease treated at UW Expansion throughout the state of Wisconsin is planned

Diagnosis Based

The database is focused on a relatively small homogenous population The registry is new so follow-up is limited

AANS: The American Association of Neurological Surgeons; EQ-5D: EuroQol questionnaire version 5D; N2QOD: National Neurosurgery Quality and Outcomes Database; NEUROPOINT SD: Neurosurgery Patient Outcomes IN Treating Patients with Spinal Disorders; ODI: Oswestry Disability Index; SF-36: Short form 36 questionnaire; SweSpine: Swedish Spine; UW: University of Wisconsin; VAS: Visual Analog Scale. Data taken from [3,23–25,102–107].

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numerous challenges exist. While some clinical dilemmas can be examined with RCTs, others will be best examined with thoughtful inclusive spine registries that provide high-quality data on large cohorts of patients who are treated with existing practice patterns and general patient populations. As mentioned by previous authors, there are several characteristics that are necessary at a minimum to make a registry successful, these include patient-based data collection, financial support for the registry and healthcare provider buy-in [21,23,28,29]. Patient-based data collection provides infor­ mation that has not been filtered through providers and, therefore, more accurately ref lects patient satisfaction and symptom trends. Obtaining the patient perspective directly is particularly important in evaluating outcomes for degenerative spine disease, since many aspects of the disease and outcomes are based on subjective experience. The challenges in patient-based data collection include building user-friendly interfaces to collect data and transfer the data in a secure and accurate fashion to the registry. Additional challenges of this mode of data collection include maintaining patient confidentiality and satisfaction, and addressing institutional review board requirements. The costs of studies using registries can be high and in some cases is similar to the cost of RCTs. In addition, most registry costs will not be finite and incurred over a narrowly defined period of time, as they are in the case of clinical trials. In the ideal circumstance many spine registries will be in operation either for a long period of time or in perpetuity. Therefore, sufficient financial resources must be provided for ongoing data collection storage and ana­ lysis. Long-term follow-up of patients and maintenance of a registry provides financial challenges and there are other practical concerns. If the time period is long, technology for both data collection and patient-treatment strategies may change. These changes may limit comparison with data collected previously and affect the utility of a registry. Finally, healthcare provider buy-in is crucial to the success of CER in spine disease. Providers must be willing to participate and also in some cases to critically appraise the data provided by registries. If the providers participating in the registry are not representative of the actual practice environment, the data provided by

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the registry may not be generalizable. Barriers to provider buy-in and participation include the lack of knowledge regarding CER and limited provider time as the modern healthcare environment continues to increase the clerical burdens placed on physicians and other providers. Unmet needs

The unmet needs are directly related to the ongoing challenges faced by CER in spine surgery. Financial support continues to be an area where improvement is needed. The money apportioned through the American Reinvestment and Recovery Act of 2009 will provide some initial funding, but ongoing funding will be needed since registry maintenance and ana­lysis are ongoing costs. In addition, institutional review boards and other administrative processes present in the medical research community need to recognize the trend toward patient registries and their value. These parties must then assist in the approval of these studies and provide streamlined and specific processes for their implementation given the low risk of these studies and the high utility of data obtained if quality patient registries can be rapidly implemented. Finally, construction of quality inclusive registries can be facilitated if all professional organizations in the spine community can work towards providing guidelines and standardization of registry design and either create larger unified registries that are highly inclusive of a multitude of practitioners and patients, or with the aide of standardized a priori questions and data collection methods, allow ease of pooling data from separate registries from the various professional organizations. If data are not pooled from separate registries, then comparison across registries may be possible. It will be important to use common validated outcomes measures to provide useful results when pooling data from registries or comparing data from different registries. Future perspective

Improvements in technology have already greatly facilitated communication and data storage. The continued advancement of technology will hasten the progress of CER in spine care as it will in other medical fields. Modern computer systems allow for the collection and ana­lysis of vast quantities of data through a user-friendly interface that can be relatively inexpensive. The

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major challenge in the future will be thoughtful experimental design, such that spine researchers ask appropriate questions and analyze the results in a useful fashion. Without careful oversight of data generation and ana­lysis, the vast quantity of information provided by clinical trials and registries has the prospect of being unhelpful or even obstructive, but thoughtful design and ana­lysis CER has the opportunity to greatly improve patient care.

Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.

Executive summary Researchers are beginning to emphasize comparative effectiveness research in spine care. Evaluation of therapeutic options has traditionally emphasized randomized controlled trials, but recognizing the limitations of this method, many researchers have recently moved towards the development of spine registries to evaluate patient outcomes for various therapeutic modalities. ■■ As the data collected by these spine registries increase, thoughtful design and ana­lysis is crucial. Patient-based data collection, financial funding and healthcare provider buy-in are necessary for registry success. ■■ Research from quality spine registries has improved patient care and may continue to do so in the future. ■■ ■■

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■■ Websites 101 Spine Tango Report International 2011.

www.eurospine.org/cm_data/SSE_2011_ annual_report_final_1.pdf 102 Swedish Society of Spinal Surgeons.

www.4s.nu/4s_eng/index.htm 103 Neurosurgery Patient Outcomes in Treating

Spinal Disorders (Neuropoint SD). www.clinicaltrials.gov/ct/show/ NCT01220921 104 The National Neurosurgery Quality and

Outcomes Database (N²QOD). www.neuropoint.org/NPA%20N2QOD.html 105 Scoliosis Research Society (SRS). An

International Organization Dedicated to the Education, Research and Treatment of Spinal Deformity. www.srs.org/research/research_topics.htm 106 NASS Blog. Latest updates for spine care

professionals. http://spineline.wordpress.com

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Degenerative spine disorders are a significant cause of patient morbidity and are a prominent factor in healthcare costs in many countries. Pressure f...
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