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9 Articles in Volume 15, Issue #3
Abuse-Deterrent Formulations
Ask The Expert: False-Positive Screen for Benzodiazepines
Clinical Diagnosis of Centralized Pain in the Age of ICD 10
Editor's Memo: The WHO Pain Treatment 3-Step Ladder
Letters to the Editor: Hormone Dosing, Adhesive Arachnoiditis
Pain in Women
PROMIS Pain-Related Measures: An Overview
Selective Interventional Spinal Techniques: Injections and Ablations
Transcranial Direct Current Stimulation (tDCS): What Pain Practitioners Need to Know

PROMIS Pain-Related Measures: An Overview

The National Institute of Health created PROMIS to develop and evaluate measures to target important health outcomes across various chronic diseases. The pain-related domains include items for pain intensity, interference, behavior, and quality.

The National Institutes of Health (NIH) implemented the Patient Reported Outcomes Measurement Information System (PROMIS) more than 10 years ago. NIH created PROMIS to develop and evaluate measures to target important health outcomes across various chronic diseases.1,2 The PROMIS project combines systematic state-of-the-science instrument development with modern measurement theory to develop health outcome assessments that provide flexibility, precision, and validity for clinical trials and clinical practice settings. PROMIS measures are based on “item banks,” sets of items that represent symptom or functional domains.

PROMIS initially focused on item banks to assess physical functioning, fatigue, social activities, depression, anxiety, and other domains, including pain-related domains. The pain-related domains include item banks for pain interference and pain behavior,3,4 and measures of pain intensity and pain quality.5,6 The PROMIS pain-related item banks and measures were developed based on systematic qualitative and psychometric research methods.3,4,7,8 Figure 1 provides a summary of the PROMIS conceptual framework.

Item-response parameter estimates enable the development of static short-forms and computerized adaptive tests (CATs).8 In addition, researchers can review the content of these item banks and relevant item location and threshold parameters, and use this information in the intelligent design of study-specific or disease-targeted measures that can be used to assess outcomes. Each CAT is unique, in that it represents an assessment approach that tailors the measurement to individual patients, allowing for very precise assessment with few items (4 to 6 items for many applications). Items are selected for individual patients based on their answers to previous items. Thus, individuals receive different sets of items depending on their locations along the health domain continuum. For example, when assessing physical functioning, if a patient responds that she cannot walk up one flight of stairs, then she is not asked questions about walking up two flights of stairs or about the performance of more strenuous activities.

This report provides an overview for clinicians of the PROMIS pain-related item banks and measures, and briefly summarizes some of the psychometric results for these measures.

Pain Intensity

Clearly, any assessment package for pain-related outcomes needs to include measures of pain intensity or severity. The PROMIS measure includes the typical 0-to-10 numeric rating scale (NRS) for pain intensity. The pain intensity NRS can be used as measure of pain severity, or can be used as part of the PROMIS Global Scale.9 In addition, there is a small set of pain severity items that cover average pain (1 item), worst pain (1 item), and pain right now
(1 item).10 These 3 items cover a broad range of the pain intensity continuum that is comparable to the pain intensity NRS (Figure 2).

Pain Interference

Pain interference refers to the degree to which pain limits or interferes with an individual’s physical, mental, and social activities. PROMIS network investigators developed a pain interference item bank based on reviews of the pain literature and existing published measures, clinical expert input, and qualitative research with patients who reported having chronic pain conditions.4 The resulting item bank contains 41 items covering the negative impact of pain on functioning. Example questions are summarized in Table 1. A 7-day recall is used, and 3 sets of response options are included (never to always; not at all to very much; never to every few hours). The PROMIS investigators have developed 4-item, 6-item and 8-item short-form pain interference scales.

Amtmann et al showed that the PROMIS pain interference item bank provides precise measurement across a broad range of the pain interference continuum.4 Scores are correlated with those of other pain-related measures, and vary significantly by pain intensity levels, number of chronic conditions, disabling conditions, and general health status. For example, pain interference scores increased with lower levels of reported health status (P<0.0001; Figure 3). Pain interference scores also varied significantly by pain intensity categories (P<0.0001; Figure 4).

 

The PROMIS pain interference item bank can be used to generate various static scales (short-forms), as well as for computerized adaptive tests. Research demonstrates that with CAT, 4 to 6 items are sufficient to assess pain interference, given the tailoring of the specific items to the functioning of the individual respondent. In addition, the PROMIS pain interference short-form and CAT scores have comparable responsiveness compared with the Brief Pain Inventory interference scale in patients with low back pain.11

Pain Behavior

Pain behaviors communicate to others that a person is experiencing pain.12,13 Pain behaviors can include verbal complaints of pain and suffering, non-language sounds, facial expressions, body posturing and gesturing, and limitations in activities. There is growing recognition that pain behavior is a key outcome of persons suffering from chronic pain.14 Direct observation provides the most objective approach to assessing pain behavior, however, self-report provides an alternative method.12 The PROMIS investigators developed a comprehensive pain behavior item bank based on self-reports that can reliably assesses the full array of pain behaviors for clinical studies.

The original PROMIS pain behavior item bank consists of 39 items covering movement (eg, move slowly, stiffness), affect (eg, irritable, angry), social interactions (eg, ask for help, withdraw), and facial/verbal expressions (eg, groan, grimace) (see Table 2, page 36). The initial pain behavior item bank was developed based on the published literature, review of existing observer-rated and self-report pain behavior instruments, clinician review, and qualitative research with patients experiencing various kinds of pain. The items cover a wide range of pain behaviors. The response scales focus on how frequently patients engage in each pain behavior using a 6-point Likert-type scale, ranging from 1 (had no pain) to 6 (always), with responses reflecting the 7-day recall period. The PROMIS investigators also have developed a 7-item short-form pain behavior scale.

Empirical evidence has supported the validity of PROMIS pain behavior scores.3 For example, pain behavior scores vary significantly by level of pain intensity, with increasing higher scores associated with increased pain intensity (see Figure 5, page 36).

More recently, Cook et al revised the PROMIS pain behavior item bank and developed the Pain Behaviors Self report (PaB-SR), a static 20-item measure of pain behaviors.15 Additional items supplement and extend the PROMIS items, and several of the existing items were revised. The recall period remains the past 7 days and the PaB-SR response options range from “never” to “always.” The PaB-SR scores also were linked to the original PROMIS T-score metric, allowing a connection between the 2 pain behavior measurement systems. Cook et al demonstrated that the PaB-SR scores were correlated with observer ratings and provided evidence supporting the validity of the PaB-SR.15

Pain Quality

There is increasing recognition that pain is a complex experience with affective, sensory, and other qualitative dimensions. Because pain has varied sensory and affective qualities, measures that target specific facets of pain might more fully describe the pain experience.16 Assessments of different pain-related sensory and quality components might assist in identifying treatments that impact pain intensity and other facets of the pain experience.16

The PROMIS network developed an initial pain quality item bank based on existing instruments, clinician review, and qualitative research in patients with various kinds of pain.5 The items covered diverse qualities of the pain experience, including items assessing piercing, stabbing, throbbing, crushing, cold, numb, pulling, dull, and aching pain. Content of the final set of pain quality items was revised based on the results of interviews. The final set of pain quality items consisted of 37 items, with frequency (never to always) and severity (none to very severe) Likert-type response scales. The recall period for all pain quality items was the past 7 days.

Based on the psychometric findings, the PROMIS developers retained a pool of 37 items for further study. Exploratory and confirmatory factor analyses demonstrated 6 distinct factors: 1) pulling/tugging pain, 2) tingling/numbness pain, 3) sharp/stabbing pain, 4) dull/aching pain, 5) pounding/pulsing pain, and 6) affective pain.5 These pain quality factors may prove useful for describing and evaluating the pain experience of patients with different kinds of pain.

Recently, a team of clinicians and measurement experts reviewed and re-evaluated the PROMIS pain quality items, which resulted in the development of a second version of the PROMIS pain quality items. The affective items were revised to simplify the question stems and response scales. The new response scales for the affective-type items are now dichotomous (ie, yes/no). Revicki et al conducted exploratory and confirmatory factor analyses on these affective items; these analyses supported the following 4 pain quality factors: 1) intolerable/unbearable, 2) worrying/horrible, 3) annoying/uncomfortable, and 4) nauseating.17

The other pain quality items also were reviewed and a number of revisions were made to the original set of pain quality items. Psychometric analyses are continuing on the revised PROMIS pain quality items, including deriving scales for assessing neuropathic pain6 and other pain quality concepts in adults and children with pain conditions.

Discussion

The PROMIS initiative focused on the development and psychometric evaluation of multiple item banks for assessing health domains, including pain-related outcomes. The PROMIS network investigators developed item banks and measures for pain interference, pain behavior, pain quality, and pain intensity. Although broad item banks were developed to assess pain interference and behavior, sets of relevant items were developed for assessing pain intensity and pain quality. Recently, the pain behavior and pain quality item banks have been revised,15,17 and psychometric analyses are continuing to evaluate these new pain-related measures.

The PROMIS pain interference item bank allows researchers to use either the established short-form scales or computerized adaptive tests to evaluate impact of pain or treatment on pain interference. In addition, researchers can develop study-specific or disease-targeted short-form measures based on the content of the questions and the available item parameters from the item response theory analyses. A PROMIS pain behavior short-form scale is available, but there may be limitations to using the short-form because of restricted coverage of pain behaviors. Although content balanced, the short-from scale may not comprehensively measure the full range of pain behaviors. The more recently developed PaB-SR may provide more comprehensive assessment of pain behaviors.15

Pain quality measures are available, and may provide important information on understanding the pain experience in patients with acute and chronic pain conditions. Askew et al identified 5 items that were associated with neuropathic pain conditions, and this scale may be useful for screening for neuropathic pain and for monitoring pain outcomes.6 Additional research is needed on the pain quality factors to determine their value in clinical research and practice settings.

Conclusion

The PROMIS pain-related measures are available for use in clinical research and clinical practice settings. A number of language translations have been completed for the PROMIS measures, including English, Spanish and other languages. Further information may be found by accessing the PROMIS website (see www.nihpromis.org). The pain-related measures and other PROMIS measures (eg, fatigue, physical function, social function, depression, etc.) also might be applicable for pain studies. The PROMIS pain-related pain measures have the potential to improve measurement of pain interference and behavior, and other outcomes, and to increase our understanding of the effects of pain on patients’ lives and function, and of the effects of treatment interventions.

 

Last updated on: April 15, 2015
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Assessment and Treatment of Chronic Pain

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