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The Need of Validated Disease-Specific Outcome Instruments for Spine Trauma

Oner, Cumhur MD, PhD*; Sadiqi, Said MD*; Lehr, Anne Mechteld MSc*; Schroeder, Gregory D. MD; Vaccaro, Alexander R. MD, PhD, MBA

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Journal of Orthopaedic Trauma: September 2017 - Volume 31 - Issue - p S33-S37
doi: 10.1097/BOT.0000000000000945
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As a greater number of individuals survive serious trauma and their life expectancies have increased substantially, the measurement of the quality of care and functional and health-related quality of life outcomes of this group becomes increasingly important. Among survivors of major trauma, those with spinal trauma comprise a significant fraction, both in numbers and in the amount of care they require. At this moment, there are no tools that are specifically designed and validated for the outcomes measurement of traumatic spinal column injury patients. Measurement of the results of interventions on the individuals' health-related quality of life is not only relevant for optimal treatment strategies but also important from the standpoint of cost-effectiveness. The outcomes of spine trauma patients have traditionally been measured either in mortality and neurologic deficits or by instruments designed for chronic conditions. Issues specific to spinal trauma patients may not be adequately addressed by these generic outcome measures or instruments designed for dissimilar patient populations. There is also a growing realization that there is not a single “objective” outcome of a traumatic incident, and that the outcome instruments should reflect the different and potentially conflicting standpoints such as the trauma survivor's, treating physician's, and care-payer's perspectives.

Existing Instruments

Review of existing literature shows that there is no outcomes measurement instrument specifically designed, validated, or universally adapted for spinal trauma patients. A review by Stadhouder et al1 identified a total of 21 different outcome measures used in spine trauma research. They concluded that there remains disagreement on the preferred outcome measures, and they found discontinuity in the evaluation of spine trauma patients in the acute/subacute and the chronic setting. Acutely, spinal trauma patients are seen as a subset of polytrauma patients; however, after the first few months, these are often treated as chronic degenerative back or neck pain patients in the long-term rehabilitation setting. Comparable results were retrieved from a recently published systematic review.2 The main focus of this review was to identify outcome measures most frequently used to evaluate the function and health of patients with traumatic injuries to their spinal column, rather than spinal cord injury (SCI). A total of 17 different frequently used outcome measures were identified, which ranged from generic outcome measures to disease- or dimension-specific instruments. Seven spine-specific questionnaires were identified, including 5 questionnaires developed for the thoracic and lumbar (TL) spine [Oswestry Disability Index (ODI), Visual Analogue Scale Spine Score (VASSS), Roland–Morris Disability Questionnaire (RMDQ), Low Back Outcome Scale (LBOS), and Prolo Scale (PS)] and 2 measuring neck-specific disability [Cervical Spine Outcome Questionnaire (CSOQ) and Neck Disability Index (NDI)]. In total, 6 dimension-specific outcomes were found, including Denis pain scale, Denis work scale, and various single item scales to assess pain, satisfaction, ability to participate in recreational activities, and return to work. In addition, 3 clinician-based outcome instruments were identified: 2 neurological function classifications represented by the Frankel scale and ASIA impairment scale and the back disability-specific Hannover spine score. Finally, the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) was identified as the commonly used generic outcome measure. An investigation of the clinimetric properties of these instruments for patients with traumatic spinal column injuries showed that all measures had a near absence of evidence for content validity, criterion validity, floor and ceiling effects, reliability, and interpretability. Overall, the findings from both reviews indicate that a wide range of patient- and clinician-reported instruments, which were not specifically designed and validated for this specific patient population, are used to assess spine trauma outcomes, and that pain and neurological status are the most frequently measured items.

To address this void, the AOSpine Knowledge Forum Trauma initiated a project to develop and validate disease-specific outcome instruments for spine trauma patients. To reflect the different perspectives of patients and the treating surgeons, 2 separate tools are being developed: the Patient Reported Outcome Spine Trauma (AOSpine PROST), and Clinician Reported Outcome Spine Trauma (AOSpine CROST).

Patient's Perspective

Patient-reported outcome measures (PROMs) have become very popular in health care. These instruments are meant to reflect purely the patient's perspective on the impact of disease and its treatment on health status and daily functioning.3 The formal definition according to the Final Patient-Reported Outcome Guidance (2009) of the United States' Food and Drug Administration (FDA) is “any report of the status of a patient's health condition that comes directly from the patient, without interpretation of the patient's response by a clinician or anyone else.” To develop a disease-specific PROM for spinal trauma patients, the AOSpine Knowledge Forum Trauma decided to use the systematic approach and methodology of the International Classification of Functioning, Disability, and Health (ICF) of the World Health Organization (WHO).4,5 The bio-psycho-social perspective of the ICF relies on a globally accepted framework to describe and classify functioning, disability, and health in people with a variety of diseases, conditions, or health states. The ICF recognizes that problems in functioning can be understood and described using different components that are hierarchically organized into different levels of detail. With 1454 categories, the ICF is comprehensive of all aspects of life and can be seen as a catalog from which appropriate items can be chosen. ICF also proposes certain procedures to make the appropriate choices toward the development of a core set for a specific condition.

This developmental process initially focused on patients sustaining injuries to their spinal column and excluded completely paralyzed and polytrauma patients, to identify specific problems related to spine trauma. In later phases of the project, this instrument will be combined or extended with measures used for paralytics or polytrauma. Four different studies were conducted in the preparatory phase of the project. Three studies aimed to identify ICF categories relevant to measure the outcomes of traumatic spinal column injuries from different perspectives. The research perspective was covered by a systematic literature review.2 Of 5117 references screened, 245 were included, and 17 different frequently used outcome measures used in spine trauma research were identified. The content of these measures were linked to 57 ICF categories using established linking rules.6,7 The expert perspective was explored through a web-based survey among 150 experienced spine trauma surgeons from all world regions and identified 13 ICF categories as most relevant.8 The patient perspective was investigated in an international empirical study including 187 patients from 9 trauma centers in 7 countries and yielded 38 ICF categories as the most important.9 Comparison of the results of these 3 preparatory studies yielded interesting findings. The systematic review showed that the most frequently used outcome measures in spine trauma research focused primarily on pain. The most relevant ICF categories identified in the expert survey related also to the same issues. However, the most relevant categories reported by the patients in the empirical study related to loss of function and limitations in activities of daily living (ADLs). Problems related to the perception of pain were much less prominent. These findings were valuable in the next phases of development. As the preinjury physical, psychological, and general health-related characteristics of patients with spinal column injury may very well deviate from those of the general population, there is an acknowledged lack of baseline or preinjury measurement.10 Therefore, the fourth preparatory study investigated various response scales for their potential use in the new PROM. The scales were not only tested for their validity and reliability but also the degree to which they are understandable for adult traumatic spinal column injury patients to accurately compare their current level of function and health with their preinjury state.11

In the next phase, a formal consensus process integrated evidence from the preparatory studies and expert opinion.12 Based on group discussions followed by voting, 25 of 159 relevant ICF categories were selected as “core categories” for patient-reported outcome measurement in adult traumatic spinal column injury patients. The adopted core ICF categories could also serve as a benchmark for assessing the content validity of existing and future outcome instruments used in spine trauma patients. The attendants of the consensus conference also selected 1 specific question format combined with the 0–100 Numeric Rating Scale (NRS-101) as the appropriate response scale. In this scale, 0 indicates no function at all, whereas 100 represents the preinjury level of function. The final instrument was named the “AOSpine PROST” (Patient Reported Outcome Spine Trauma). Subsequently, a draft version of the AOSpine PROST in the Dutch language was developed by clustering the identified 25 core ICF categories into 19 items and implementing those items into the selected response scale (Table 1). These items cover a wide range of domains, including and beyond the scope of ADLs, such as not only muscle strength and stiffness but also emotional function, urination, and defecation. A pilot study showed very good results and after only some minor adaptations a definitive Dutch version was developed.13 A careful translation into English followed and the linguistic equivalence of both versions was checked using established guidelines.14 Currently, both the Dutch and English versions of the AOSpine PROST are being subjected to further validation in a multicenter international study.

Items and Response Scale of the AOSpine Patient Reported Outcome Spine Trauma (AOSpine PROST)

Clinician's Perspective

Several outcome instruments are designed to be used by health professionals to assess the functional status of spinal trauma patients, especially with neurologic deficits. These include the spinal cord independence measure (SCIM), walking index for SCI (WISCI), and functional independence measure (FIM). The SCIM was specifically developed for SCI patients to evaluate their performance of ADLs and to make functional assessments sensitive to change.15 Three versions of the tool (SCIM I, II, III) have been developed since its first publication in 1997. The scale is composed of 19 items in 3 different areas of function, including self-care, respiration and sphincter management, and mobility. The score of independence ranges from 0 to 100, in which 0 is the worst score and indicates total dependence, whereas 100 indicates total independence. The assessment is performed by therapists and/or nurses and requires 30–45 minutes. Overall, the SCIM has shown good results for sensitivity, reliability, and validity to measure functional outcomes in individuals with severe SCI.1 The WISCI was also specifically designed for SCI patients and focuses on the measurement of mobility.16 It is a scale for walking limitation secondary to impairment and showed high sensitivity and good correlation of validity in spinal cord–injured patients.1 The FIM was developed as a basic measure of the severity of disability regardless of the underlying impairment.17 Nevertheless, it is the most widely used functional outcome measure in SCI patients.18 It evaluates a narrow set of 6 domains to reflect the impairments specific to SCI (self-care, sphincter management, transfers, locomotion, communication, and social cognition). The assessment is based on 18 tasks. Rating the FIM is quite complex and requires training. Several studies have shown the validity and reliability of the FIM, and that it is most useful in measuring burden of care.18

The SCIM, WISCI, and FIM are mainly used in the rehabilitation setting and focus on the impact of severe neurologic function loss only, which makes them not suitable for use in patients with mild, resolving, or no neurological deficits. Moreover, these are so-called “observer reported outcome measures” that are scored on the basis of patients' performance, and do not reflect the perspective of the treating surgeons. Most recently, AOSpine Knowledge Forum Trauma has developed a new concept of “clinician-reported outcome measurement” in spine trauma care, the “AOSpine CROST” (Clinician Reported Outcome Spine Trauma). There is no definition to date from the FDA for this certain type of outcome measurement instruments. It can be defined as “assessments performed by an observer with professional training relevant to the measurement, and requiring basic knowledge and training to perform the assessment successfully.” A similar concept is already known in several medical conditions that require the observations of trained clinicians. In central nervous system diseases such as Alzheimer, depression, and schizophrenia, patients are poor reporters of their symptoms because of diminished insight. The Clinical Global Impression–Schizophrenia (CGI-SCH) scale is an example of a clinician-reported outcome tool that was designed to assess positive, negative, depressive, and cognitive symptoms in schizophrenia.19 It helps clinicians differentiate manic from positive symptoms and depressive from negative symptoms. The clinician rates both the severity and degree of change of these 4 domains individually and provides an overall global subjective rating on a 7-point verbal rating scale. This instrument has shown to be valid and reliable to evaluate severity and treatment response in schizophrenia and is currently being used in observational studies and routine clinical practice. Another example of patient populations that are eligible for clinician-reported outcomes are patients with traumatic brain injury or stroke, who are not able to report on their health status.

In the case of the treatment of spinal trauma patients, several clinical and radiological parameters are generally used by treating surgeons to evaluate treatment results after traumatic spine injuries. To determine the further course of treatment, an estimation of any expected problems with respect to these outcomes on the short-term and long-term health of the patient is made by the treating surgeons. In this aspect, the surgeon's assessment may differ substantially from the patient's perception, the latter being reflected by PROMs.20,21 These discrepant views have also been addressed for a variety of other diseases, including metastatic breast and prostate cancer,22 multiple sclerosis,23 and rheumatoid arthritis.24

Therefore, besides the AOSpine PROST that reflects the patient's perspective, there is also a need for a tool that incorporates the most relevant clinical and radiological parameters to reflect the clinician's perspective adequately. The AOSpine CROST is a simple, reliable, and quick to administer tool that is completed by the treating surgeons and is able to predict the course and clinical outcomes of spine trauma patients. Together the AOSpine CROST and the AOSpine PROST provide a complete view of patients' function and health in relation to their spine injury. The developmental process of the AOSpine CROST started with the identification of relevant clinical and radiological parameters. In this context, 2 separate cross-sectional online surveys were conducted among a worldwide sample of experts with substantial experience in the clinical practice of spine trauma. One survey focused on the identification of relevant parameters for the TL (TL-survey)25 and another for the subaxial cervical spine (C-survey).26 Based on the previously discussed systematic review,2 the recently developed AOSpine TL- and C-classification systems27,28 and expert interviews, 16 parameters were included in the TL-survey and 21 in the C-survey as potentially relevant. The most relevant clinical and radiological parameters were identified by these surveys and formalized in a draft version of the AOSpine CROST. After discussing and pilot testing this draft version among clinical cases during an expert committee meeting, a definitive version to be validated was developed consisting of 10 parameters (Table 2). Various response formats are currently being tested in a reliability study. It is not possible to assign specific, more or less “objective,” values to these parameters. For example, a specific value for kyphosis that differentiates between “good” and “bad” sagittal alignment cannot be given. Partly because a wide range of values can be found in the literature that are indicated to be associated with the vaguely defined concept of “instability.” However, as shown by a recently conducted study, worldwide variations are seen in measurement techniques preferred by treating spine surgeons to assess different radiographic modalities.29

Parameters of the AOSpine Clinician Reported Outcome Spine Trauma (AOSpine CROST)

Recommendations and Future Perspectives

This article focused on PROMs and clinician-reported outcome measures in spine trauma care. In contrast to many instruments used in spine trauma care, which were not specifically designed for this patient population, the AOSpine PROST and CROST hold promise as useful instruments to measure the outcomes of spine trauma patients with and without neurological deficit, making it more feasible for clinical use as well. After the ongoing validation in patients sustaining injuries to their spinal column, the AOSpine PROST will be extended to severe spinal cord–injured patients. Concerning the AOSpine CROST, its content validity has been tested in expert meetings including a panel of internationally renowned experts on spine trauma. Currently, a study is being conducted to assess the inter and intrarater reliability of this tool, and further validation studies are in progress to assess its construct validity and responsiveness. We do recognize that also other categories of measurement should be taken into account when assessing treatment outcomes in the daily clinical practice or in comparative effectiveness analyses. Those include among others baseline patient factors (eg, basic sociodemographic factors or comorbidities), treatment factors (eg, surgical procedures), and perioperative events (eg, immediate postoperative complications).30

In the near future, the aim is to cross-culturally translate and adapt the AOSpine PROST in many languages. Treating surgeons around the world are encouraged to use these tools in daily clinical practice and for research purposes to create and contribute to evidence-based and patient-centered care. Using the same outcome measures that are specifically developed and validated for traumatic spine injuries will allow us to compare the outcomes of various treatments in a valid and reproducible fashion to reduce the ongoing controversies and provide the best treatments for our patients.


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spine trauma; outcome measurement; outcome instrument; patient-reported outcome measure; clinician-reported outcome measure

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