Introduction

Persistent and severe pain is common after a spinal cord injury (SCI),1, 2 and most individuals experience neuropathic and/or musculoskeletal pain at 1 year after injury.3 The persistence of pain after SCI often leads to higher levels of depression,4 significant psychosocial impact5, 6, 7, 8 and reduced quality of life9 by interfering with sleep, mood and daily activities including social activities and work.10

Pain in people with SCI is classified in the broad categories nociceptive, neuropathic (at or below level of injury), other or unknown.11 The neuropathic pains are often associated with various sensory abnormalities including allodynia and hyperalgesia,12, 13 and research suggests that assessment of these can help define phenotypes and/or predict pain development or treatment responses.3, 14, 15

The multidimensionality of pain is emphasized by the dynamic interaction between biological factors, psychological status, and social and cultural factors; this makes the pain experience highly individual and unique. Although biological factors may cause, maintain and modulate pain after SCI, psychological factors can exert a powerful influence on the perception and impact of pain, and social factors may modulate the impact and responses to these perceptions.16, 17 Thus, the interrelationships between persistent pain, psychosocial factors, and physical and functional impairments underscore the importance of a multimodal approach to the assessment, treatment and rehabilitation of individuals who experience chronic pain after their SCI.18, 19 The chronicity of pain associated with SCI also suggests that personal adaptation and coping skills are critical for achieving optimal quality of life after SCI.20, 21

The International Spinal Cord Injury Pain Data Sets (ISCIPDSs) consist of a basic (ISCIPBDS) and an extended (ISCIPEDS) data set. The information collected in the ISCIPEDS should be considered supplemental to the information collected in the ISCIPBDS. The ISCIPBDS v2.022 contains a minimal amount of clinically relevant information concerning pain (for example, pain interference, probable pain diagnosis, location, intensity and duration of pain) that can be collected in the daily practice of health-care professionals with expertise in SCI. The ISCIPBDS v2.0 was shortened from its original format23 to increase its clinical utility and to reflect the new SCI pain taxonomy.11 The ISCIPBDS was adopted by the National Institute of Health, National Institute of Neurological Disorders and Stroke (NINDS) and Common Data Elements (CDEs) as a supplemental/highly recommended data set to be collected in clinical SCI pain research (www.commondataelements.ninds.nih.gov/SCI.aspx#tab=Data_Standards).24

The organization of the extended data set is directly based on the pain problems identified in the basic data set and is intended to be used in research studies and be collected by researchers or health-care professionals familiar with SCI. Data should be collected by interview (or the recommended mode of administration for a specific instrument) and by clinical examination. The ISCIPEDS was designed to evaluate the following domains: (i) Pain symptoms (for example, temporal course, severity, unpleasantness, tolerability and pain type). Pain symptoms are particularly important to evaluate in populations such as SCI, where pain is typically heterogeneous, persistent and often severe; (ii) Sensory signs to detect and quantify common sensory abnormalities associated with clinical pain (for example, abnormal responses to light touch, pinprick and cold sensation). The sensory measures were intentionally selected to be appropriate for bedside examination to facilitate their use. Identification of symptoms and signs associated with neuropathic pain may not only facilitate a better understanding of the clinical condition but may also provide a foundation for subgroup analyses in clinical trials and thus facilitate future mechanism-based treatment interventions;25, 26 (iii) Treatments used currently or in the past 12 months (for example, dose (if appropriate), frequency, adverse effects and the person’s rating of global impression of change).27 Information regarding a person’s previous and current experience with various treatment interventions is vital for the planning of clinical studies and screening of potential participants for a clinical trial; (iv) Psychosocial domains and comorbid conditions including outcomes (for example, quality of life, satisfaction with life), mediating factors or comorbid conditions (for example, depression, anxiety).

Presently, the evidence base in the SCI pain research field does not strongly support the use of specific instruments above others. Therefore, the selection of specific instruments for a research study should primarily reflect a study’s purpose and aims. The ISCIPEDS includes multiple measures for each domain with similar purposes and equivalent psychometric properties. However, for future revisions and updates of the ISCIPEDS, the utility of specific domains and instruments will be reevaluated as new evidence becomes available.

The overall purpose of the ISCIPDSs is to standardize the collection and reporting of pain in the SCI population and to encourage investigators in this field to assess several critical pain-related domains in research studies. Moreover, the use of comparable sets of outcome measures in research studies will increase efficiency and facilitate collaborations, translation, interpretation and application of results.

Materials and methods

The members of the interdisciplinary ISCIPDS working group have extensive experience in both the clinical management and the clinical research of pain associated with SCI. Each member was appointed by one of the four major organizations with a significant interest in this area of research (that is, International Spinal Cord Society (ISCoS), American Spinal Injury Association (ASIA), American Pain Society (APS) and International Association for the Study of Pain (IASP)). For the ISCIPEDS, one additional psychologist (ER) specializing in medical/clinical psychology and public health was added to the group.

The recommendations of instruments and methods were based on the criteria including (i) their relevance to individuals with SCI and chronic pain, (ii) the existence of published findings supporting the utility of the measures selected in samples of individuals with SCI, and to the greatest extent possible (iii) their availability in the public domain. Consistent with the development of the ISCIPBDS,22 the guiding principle was to prepare a data set that could be used without added cost by clinicians in various settings and countries and without the need of advanced technical equipment. To ensure consistency in the data collection and facilitate interpretation, detailed information is provided in a syllabus for each specific variable and response category. The development process of the ISCIPEDS followed the steps briefly outlined in Table 1.

Table 1 Outline of the development of the final version of the International Spinal Cord Injury Pain Extended Data Set

Results

The ISCIPEDS includes several important assessment domains that are divided into four sections.

Pain symptoms

This section is intended to assess individual variables related to the temporal course, severity, unpleasantness, tolerability of pain, as well as questionnaires related to the pain type and symptom severity.

Overall pain

These measures are not only intended to provide an overall assessment of pain (including all pain problems) but can also be used for individual pain problems (previously identified by the ISCIPBDS), if appropriate (Appendix A). This section includes the following items:

Number of days with pain in the last 7 days including today. This variable evaluates the constancy of pain by specifying the total number of days with pain during the last 7 days, including today, and the response categories range from 0=none to 7=seven days. ‘Today’ is the day the individual answers the question regardless of the time of day. The duration of pain during the day is not relevant to this question.

Worst pain intensity in the last week. Pain intensity is the most common pain domain assessed in research and clinical settings. Although different rating scales have proven to be valid for assessing pain intensity, including the Numerical Rating Scale (NRS), the Verbal Rating Scale and the Visual Analog Scale, the 0–10 NRS has the most strengths and fewest weaknesses of available measures.28 Moreover, the 0–10 NRS has been recommended by the IMMPACT consensus group for the use in pain clinical trials29 and by the 2006 NIDRR SCI pain outcome measures consensus group.30

The 7-day time frame was selected to balance the need to assess pain over a long enough epoch to capture usual pain, against the need to keep the time frame short enough to maximize recall accuracy. The instruction and end points used were designed to differentiate between pain intensity and pain unpleasantness.31 For example, the intensity of pain is related to how strong the pain feels and the unpleasantness of pain is related to how disturbing the pain is. To better understand the difference between pain intensity and unpleasantness, one can substitute the word ‘sound’ for ‘pain’. Pain intensity is analogous to the loudness of a sound, whereas unpleasantness is analogous to the aversiveness of a sound not necessarily related to its loudness.

The worst pain intensity experienced during the last week is rated on a 0–10 NRS (ranging from 0= ‘No pain’ to a maximum of 10= ‘The most intense pain imaginable’). Please note that ‘last week’ specifically refers to the last 7 days including today.

Average pain unpleasantness in the last week. Pain is a result of sensory, cognitive and affective dimensions, and the emotional dimension can be evaluated separately from intensity.32 The average pain unpleasantness is rated on a 0–10 NRS (ranging from 0= ‘Not at all unpleasant’ to a maximum of 10= ‘The most unpleasant pain imaginable’). Please note that ‘last week’ specifically refers to the last 7 days including today.

Number of days with manageable/tolerable pain in the last 7 days including today. Manageable or tolerable pain is a construct reported by Zelman et al.33 and not specific to pain after SCI. Focus group methodology has suggested that manageable or tolerable pain is pain that permits concentration on something other than the pain, perhaps by using a treatment or self-remedy that ‘takes the edge off’ pain and allows performance of daily activities or ‘getting something done.’ Other factors associated with manageable pain are lower levels of negative mood, feeling well enough to socialize and not experiencing excessive adverse effects of ongoing treatments including medication.

This variable specifies the total number of days with pain during the last 7 days, including today, and the response categories ranges from 0=none to 7=seven days. ‘Today’ is the day the individual answers the question regardless of the time of day. The duration of manageable/tolerable pain during the day is not relevant to this question.

Individual pain problems

These measures are intended to be performed for each separate pain problem identified in the ISCIPBDS (Appendix A).

Pain intensity in present moment. The present pain intensity for (up to) three pain problems (the three worst pain problems respondents experience) is rated on a 0–10 NRS (ranging from 0= ‘No pain’ to a maximum of 10= ‘The most intense pain imaginable’). Please note that ‘present’ specifically refers to this moment.

How long does your pain usually last? This variable provides an estimate of the duration of pain. Some pain types are very brief and may be felt several times per day. This question refers to the duration of each separate pain event. Response categories are the following: 1 min or less; more than 1 min but less than 1 h; at least 1 h but less than 24 h; at least 24 h but not continuous; constant or continuous; and unknown. The duration of pain can be defined when a specific pain follows a predictable pattern. If no predictable pattern for a specific pain exists, the answer ‘unknown’ is given.

When during the day is the pain most intense? This variable identifies the diurnal peak in pain intensity. Response categories are the following: Morning, Afternoon, Evening, Night and Unpredictable; pain is not consistently more intense at any one time of day. ‘Morning’ is between 6.01 am and Noon (06.01 and 12.00); ‘Afternoon’ is between Noon and 6.00 pm (12.01 and 18.00); ‘Evening’ is between 6.01 pm and Midnight (18.01 and 24.00); ‘Night’ is between Midnight and 6.00 am (00.01 and 06.00).

Recommended questionnaires

These questionnaires are intended to provide supplemental information as appropriate for a specific purpose or interest (Table 2).

Table 2 Pain symptoms: recommended questionnaires for the assessment of pain type or pain symptom severity

Sensory signs

These assessments are intended to detect and quantify common sensory abnormalities in a painful area at or below the level of injury (Appendix B). The sensory bedside assessment includes abnormal responses to light touch, pinprick and cold sensation compared with a non-affected control area above the level of injury. The sensory measures were intentionally selected to be appropriate for bedside examination and to detect and quantify sensory abnormalities, that is, mechanical allodynia (pain in response to an innocuous mechanical stimuli), mechanical hyperalgesia (exaggerated response to a painful mechanical stimulus) and thermal allodynia (pain in response to an innocuous thermal stimuli) commonly associated with neuropathic pain types.

Dynamic light touch

Dynamic light touch can be assessed by light stroking the skin with an innocuous moving stimuli, for example, a cotton wisp, cotton wool tip or a brush (for example, Somedic standardized brush, Sweden), of approximately 2 cm with a speed of 1–2 cm s−1.34 Sensation is rated as normal (compared with a control area in a non-affected skin area), absent (no sensation felt), hypoesthesia (decreased sensation compared with control area), hyperesthesia (increased sensation compared with control area), allodynia (light touch provokes pain) or other (changed sensation that cannot be categorized otherwise). If allodynia is present, the pain is rated on a 0–10 NRS (ranging from 0= ‘No pain’ to a maximum of 10= ‘Pain as bad as you can imagine’).

Pinprick

Pinprick sensation can be assessed by pricking the skin with a disposable safety pin or calibrated monofilaments, for example, Semmes-Weinstein monofilaments or other custom-made weighted pinprick stimuli (Rolke et al.34). Pinprick is a nociceptive stimulus that normally evokes pain. Sensation is rated as normal when pain evoked in the painful area is no different than in the control area, absent when there is no evoked pain sensation, hypoalgesia when pain evoked in the painful area is less intense than in the control area, hyperalgesia when pain evoked in the painful area is more intense than in the control area, and other (changed sensation that cannot be categorized otherwise). If hyperalgesia is present, the pain is rated on a 0–10 NRS (ranging from 0= ‘No pain’ to a maximum of 10= ‘Pain as bad as you can imagine’).

Cold

Cold sensation can be assessed using a cold thermoroller (Somedic Sweden) of 20 or 25 °C, a piece of cold metal or an acetone droplet. For determination of cold detection and cold pain thresholds, thermal tests can be performed using thermodes (TSA, Medoc, Israel or MSA, Somedic, Sweden); see Rolke et al.34 Sensation rated as normal (compared with a control area in a non-affected skin area), absent (no sensation felt), hypoesthesia (decreased sensation compared with control area), hyperesthesia (increased sensation compared with control area), allodynia (an innocuous cold stimuli provokes pain) or other (changed sensation that cannot be categorized otherwise). If allodynia is present, the pain is rated on a 0–10 NRS (ranging from 0= ‘No pain’ to a maximum of 10= ‘Pain as bad as you can imagine’). Because environmental temperature may affect skin temperature and thus thermal testing it is important to record the room temperature when testing.

Treatments

Information regarding a person’s previous and current experience with various treatment interventions is important both for the planning of clinical studies and facilitates screening of potential participants for a clinical trial (Appendix C). The ISCIPEDS is designed to capture information regarding both past (last 12 months) and current treatments. Because of possible recall biases, the effectiveness of past treatments are not captured in detail but only whether a person has had the treatment in the past 12 months and if it was helpful or not, or unknown. For current, ongoing treatments, more details are captured, including the dose (if appropriate), frequency of treatment, any adverse effects and a rating of the person’s global impression of change.27

Past treatment

This variable specifies treatments for pain received in the past and treatment response. The respondent is to indicate (‘Check’) each treatment that they have received in the past for their pain. Where possible, the respondent also indicates whether it was helpful (‘Yes’) or not helpful (‘No’). If the respondent cannot remember or is uncertain about effectiveness, they indicate ‘Uncertain’. This section can be completed on one form to indicate treatments and responses for overall pain or on multiple forms for each specific pain type. Because of the fact that the management of pain in SCI is challenging with a wide range of treatments being tried that include pain medications—such as opioids, non-steroidal anti-inflammatory drugs, acetaminophen, tricyclic antidepressants and anticonvulsants—physical therapy and alternative treatment approaches—such as massage, marijuana, acupuncture and hypnosis,35, 36, 37 self-management,38 relaxation and psychotherapy—and procedural and surgical interventions, the list provided is very long to cover the most common options.

Current treatment

This variable specifies the current treatments for pain, timing of treatment, response and side effects. The respondent is to indicate current treatments for pain including dose (‘Dose’), if a medication, and frequency (‘How often’). Effectiveness is assessed using the Patient Global Impression of Change (‘PGIC’). 27, 30 Any side effects or adverse events (‘Side effects/adverse events’) related to the treatment are also to be noted. This section can be completed on one form to indicate treatments and responses for overall pain or on multiple forms for each specific pain.

Psychosocial domains and comorbid conditions

This section is intended to assess outcomes, mediating factors or comorbid conditions (for example, depression, anxiety, quality of life) (Table 3). The psychosocial domains that researchers should consider assessing in their studies of SCI pain include outcome variables, mediating variables and comorbid conditions that would be of interest to those seeking to develop, test or expand biopsychosocial models of SCI-related pain. The ISCIPEDS working group selected those domains and identified potential measures of those domains, as a function of (i) their relevance to individuals with SCI and chronic pain and (ii) the existence of published findings that support the utility of the measures selected in samples of individuals with SCI, and as much as possible (iii) their availability in the public domain.

Table 3 Psychosocial domains and comorbid conditions: recommended questionnaires

Discussion

There is a vast array of outcomes measures that have been recommended for use in neuropathic pain research39 and in SCI pain research specifically.30 A systematic review of all such measures is beyond the scope of the ISCIPEDS. Although not all of the recommended measures included in the ISCIPEDS were developed specifically for individuals with SCI, it was the consensus of the expert panel that the measures selected are those that would be most useful in SCI populations. More research will be needed to help establish their psychometric properties in individuals with SCI, and, pending the findings from this research, future recommendations may differ somewhat from our current ones. We recommend that researchers carefully examine the appropriateness of any measure they might consider using with respect to utility in the SCI chronic pain population. For example, standard measures for pain-related outcomes may have content that can be inappropriate for people with SCI (for example, pain intensity with walking) or that can be misleading if endorsed (for example, unusual sensory experiences). The instruments in the ISCIPEDS were selected in part to minimize that problem. The reader is also referred to the SCIRE (www.scireproject.com) and NINDS CDEs (www.commondataelements.ninds.nih.gov/SCI.aspx) websites where an extensive number of outcome measures are evaluated with respect to their applicability and psychometric properties. Although the measures reviewed in these loci are not focused only on pain per se, they offer other resources for SCI researchers who want to use the most valid scales, particularly those that are being proposed for adoption across studies.

Data archiving

There were no data to deposit.