Chronic pain presents two broad challenges to proper assessment: the inherently subjective nature of pain complaints and the wide-ranging influence of chronic pain on patients’ functioning. These challenges necessitate a systematic approach that involves standardized assessment of multiple domains of functioning through the use of several assessment techniques, including questionnaires, behavioral observation, psychophysiologic measurement, diary data, and reports of significant others. This chapter begins with a brief discussion of the clinical goals of psychological and behavioral assessment of patients with persistent pain, provides a rationale and context for the use of psychological assessment in the practice of pain management, articulates recommendations for the core domains of assessment, and provides an overview of the psychological assessment process. The remainder of the chapter provides specific information about some of the most commonly used psychological and behavioral assessment strategies for general use across chronic pain conditions. Disease-specific measures may also be of interest to clinicians but are not specifically covered in this chapter. Examples include the Oswestry Disability Questionnaire (lower back pain), Western Ontario and McMaster Universities Osteoarthritis Index (osteoarthritis), and the Neuropathic Pain Scale (neuropathic pain).
Clinical Objectives
Psychological and behavioral assessment of pain serves several clinical goals. First, data gathered in the assessment process provide important information about a patient’s pain experiences, pain treatment history, current and past emotional and physical functioning, and beliefs about pain. Thorough assessment of the multidimensional nature of a patient’s pain experiences not only informs clinicians’ treatment planning by identifying problems and intervention targets but also reinforces the multidimensional nature of pain to the patient, which may enhance engagement in future treatment modalities. Second, assessment allows the clinician to identify a patient’s strengths and weaknesses and the factors that contribute to the development and maintenance of problems in physical, social, and emotional functioning. This information can direct selection of the treatment modality most likely to correspond to the patient’s strengths and the intervention targets most related to the patient’s specific functional deficits. Third, assessment allows the clinician to identify comorbid psychiatric or behavioral conditions that may interfere with pain coping and overall adjustment. Fourth, assessment can determine whether the patient is psychologically appropriate and likely to benefit from surgical or invasive procedure if medically indicated. Finally, thorough assessment of a patient’s pain complaint and functioning at baseline provides an important benchmark against which the efficacy of future treatments can be measured. Assessment should not stop after the initial visit but should be ongoing throughout the treatment process. This allows identification of new problems, quantifies progress across domains, and facilitates refinement or revision of treatment if necessary. Post-treatment assessment is imperative to evaluate the overall success of the treatment, as well as the differential success of the treatment across various domains of function such as pain intensity and social, emotional, and physical functioning.
Use of Psychological and Behavioral Assessment in the Practice of Pain Management
Multidimensional psychological and behavioral assessment of a patient with pain can assist a multidisciplinary pain team or treating clinician in several ways. Multidimensional assessment serves as a foundation for planning treatment and subsequent evaluation of treatment outcomes. Psychological and behavioral assessment may also reveal the need for adjunctive psychological treatment of preexisting or emerging psychosocial difficulties that may interfere with medical treatment of the patient’s painful condition. Psychological assessment can provide information about the patient’s motivation and readiness to engage in treatment, as well as treatment preferences. Finally, psychological assessment can provide data about a patient’s suitability for surgical or other invasive procedures under consideration.
When making a request for a psychological and behavioral assessment it is necessary to explicitly state the reasons for the request or pose a question to be answered about the patient or the patient’s treatment. It is helpful for the psychologist or behavioral specialist to understand the specific question that the clinician or team is trying to answer about a patient to perform a thorough evaluation and provide meaningful feedback. Although any psychological or behavioral assessment should be multidimensional and include all relevant domains of function, the specific measures used and the areas of most intense focus differ depending on the consultation question.
Overview of the Psychological and Behavioral Assessment Process
Ideally, psychological and behavioral assessment of a patient with chronic pain should follow an approach in which hypotheses are generated and tested. The assessment should begin broadly; as problems are identified, the clinician can hypothesize contributing and maintaining mechanisms. The assessment process will be increasingly focused and behaviorally oriented as the hypothesized mechanisms are investigated. Generally, the assessment process begins with a standardized interview that assesses the pain complaint, as well as the patient’s physical, emotional, social, and occupational functioning. This allows assessment of the patient’s past and present level of functioning and the temporal association of any changes in functioning to the pain complaint. In addition to the information gained in the interview, questionnaires, diaries, behavioral observations, reports by significant others, and medical record information may be used as adjunctive sources of information. Use of multiple adjunctive measures helps avoid the biases or error associated with reliance on a single assessment strategy. Hypotheses about the factors that initiated and maintain problems in adjustment and functioning are generated and refined throughout the assessment process. Ultimately, the validity of hypotheses is tested by examining the patient’s response to treatment.
For example, anxiety and fear of pain have been shown to contribute to unfavorable outcomes in persons with chronic pain complaints. Significant functional disability can be associated with fear of pain and further injury, such as behavioral avoidance, muscle deconditioning as a result of reduced activity, muscle hyperreactivity in response to stress, negative and distorted cognitions about the adverse effects of activity, and psychological distress secondary to restricted access to pleasant and rewarding activities. Thus, when an initial interview provides evidence of a significant decline in physical functioning and the presence of anxiety, the process just described becomes a reasonable hypothesis and avenue for more targeted assessment through the use of specific questionnaires, diaries, or reports by significant others. Ultimately, the assessment process should result in a model that describes the patient’s specific pain experience; explicate how that patient’s beliefs, experiences, strengths, and weaknesses have resulted in the current level of functioning across domains; and provide an individualized treatment plan that uses these hypotheses to target specific factors for intervention.
Overview of the Psychological and Behavioral Assessment Process
Ideally, psychological and behavioral assessment of a patient with chronic pain should follow an approach in which hypotheses are generated and tested. The assessment should begin broadly; as problems are identified, the clinician can hypothesize contributing and maintaining mechanisms. The assessment process will be increasingly focused and behaviorally oriented as the hypothesized mechanisms are investigated. Generally, the assessment process begins with a standardized interview that assesses the pain complaint, as well as the patient’s physical, emotional, social, and occupational functioning. This allows assessment of the patient’s past and present level of functioning and the temporal association of any changes in functioning to the pain complaint. In addition to the information gained in the interview, questionnaires, diaries, behavioral observations, reports by significant others, and medical record information may be used as adjunctive sources of information. Use of multiple adjunctive measures helps avoid the biases or error associated with reliance on a single assessment strategy. Hypotheses about the factors that initiated and maintain problems in adjustment and functioning are generated and refined throughout the assessment process. Ultimately, the validity of hypotheses is tested by examining the patient’s response to treatment.
For example, anxiety and fear of pain have been shown to contribute to unfavorable outcomes in persons with chronic pain complaints. Significant functional disability can be associated with fear of pain and further injury, such as behavioral avoidance, muscle deconditioning as a result of reduced activity, muscle hyperreactivity in response to stress, negative and distorted cognitions about the adverse effects of activity, and psychological distress secondary to restricted access to pleasant and rewarding activities. Thus, when an initial interview provides evidence of a significant decline in physical functioning and the presence of anxiety, the process just described becomes a reasonable hypothesis and avenue for more targeted assessment through the use of specific questionnaires, diaries, or reports by significant others. Ultimately, the assessment process should result in a model that describes the patient’s specific pain experience; explicate how that patient’s beliefs, experiences, strengths, and weaknesses have resulted in the current level of functioning across domains; and provide an individualized treatment plan that uses these hypotheses to target specific factors for intervention.
Domains of Functioning
The multidimensional nature of chronic pain necessitates a broad assessment of multiple domains of functioning to provide a valid snapshot of the patient’s unique pain experience and meaningfully guide intervention strategies. A useful guide for the assessment process is the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) group consensus statement regarding the core outcome domains that should be assessed, as well as recommended instruments for measuring these domains, when evaluating the efficacy of a pain treatment.
These recommendations, though originally generated to aid researchers in increasing comparability across randomized controlled studies of pain treatments, can be useful to the clinician in guiding assessment. The IMMPACT group, which consists of recognized experts drawn from academia, government agencies, and the pharmaceutical industry, recommends assessing the following chronic pain domains: pain, physical functioning, emotional functioning, patient ratings of improvement and satisfaction with treatment, treatment-related symptoms and adverse events, and patient disposition. Additionally, through literature review and expert consensus the group has provided recommendations regarding specific assessment instruments within each domain that are applicable across a diverse range of pain complaints. Most recently, this same group has provided recommendations for the future development of patient-oriented outcome measures that may provide more sensitive and efficient assessment of the key outcome domains relevant to a comprehensive assessment of patients with pain. To date, however, there are no prospective data to support the routine application of such measures in clinical care settings.
Overview of Assessment Strategies
Multiple assessment strategies such as interviews, standardized questionnaires, diaries, behavioral observation, psychophysiologic evaluation, and assessment of family members and significant others are commonly used to investigate and quantify the pain experience and concomitant physical and emotional functioning. The use of multiple, standardized assessment measures is encouraged to obtain comprehensive, valid, and reliable information.
A well-conducted clinical interview can be a rich source of information on a patient’s pain and pain treatment history, as well as the resulting physical, emotional, behavioral, and cognitive responses. The interview also provides an opportunity for clinicians to interact with the patient, establish rapport, and develop an impression of the patient’s receptivity to rehabilitation and treatment efforts. Interviews may be standardized or unstandardized. Even when conducting an unstandardized interview it is useful to systematically investigate a prespecified set of domains ( Box 16.1 is an example of an interview structure used in the author’s [RK] comprehensive pain management clinic).
Demographics
Age, marital status, race, etc.
Referral Source
Referring MD and service, reason for referral
Behavioral Observations
Noteworthy pain behavior indicative of psychiatric disturbance; otherwise, state “unremarkable”
Pain Complaints and Treatment History
Please ask the patient the location of the pain sites, and then copy and paste questions 1 through 7 for each pain site. If the patient describes a pain site as running through the leg, knee, and foot, check all sites below but evaluate as one pain site. Thus, for a patient who identifies 3 pain sites: lower back region, right hip and leg, and hands, record 3 pain sites here and then complete questions 1 to 7 three times, each time identifying a different pain location “lower back,” “hip and leg,” and “hand.” Qualify when necessary (e.g., left leg only; write this in).
- 1.
LOCATION OF PAIN
[ ] Head/face, [ ] neck, [ ] shoulder, [ ] arm, [ ] hands
[ ] Stomach/abdomen, [ ] upper back, [ ] lower back, [ ] hip, [ ] leg
[ ] Knee, [ ] foot, [ ] anal, [ ] genital
[ ] Whole body, [ ] other sites (specify)
- 2.
INTENSITY OF PAIN
Patients rate their average level of pain over the past week as follows:
0—–1—–2—–3—–4—–5—–6—–7—–8—–9—–10
No Pain
Worst Possible Pain
Worst pain gets:
Best pain gets:
Average pain rating:
- 3.
QUALITY OF PAIN (Do not prompt; use the patient’s own words when possible.)
[ ] Dull, [ ] stabbing, [ ] hot-burning, [ ] shooting, [ ] aching
[ ] Piercing, [ ] tingling, [ ] numb, [ ] squeezing, [ ] throbbing
[ ] Pulling, [ ] sharp, [ ] cramping, [ ] gnawing, [ ] heavy
[ ] Tender, [ ] radiating, [ ] deep
[ ] Other (specify)
- 4.
ONSET/DURATION
Approximate time the pain started:
- 5.
VARIATIONS/PATTERNS/RHYTHMS
The pain is [ ] constant, [ ] intermittent, [ ] episodic/recurring, [ ] other (specify)
- 6.
WHAT RELIEVES THE PAIN?
[ ] Sitting, [ ] lying down, [ ] standing, [ ] heat, [ ] cold, [ ] rest
[ ] Distraction, [ ] exercises, [ ] movement
[ ] Other (specify)
- 7.
WHAT CAUSES OR INCREASES THE PAIN?
[ ] Sitting, [ ] lying down, [ ] standing, [ ] heat, [ ] cold, [ ] rest, [ ] exercises
[ ] Movement
[ ] Other (specify)
- 8.
EFFECTS OF PAIN
Other associated symptoms: [ ] nausea, [ ] vomiting, [ ] dyspnea
[ ] Confusion, [ ] weakness, [ ] numbness
[ ] Other (specify)
The pain affect the patient’s
[ ] Sleep, [ ] movement, [ ] energy
[ ] Lifestyle, [ ] personal relationships, [ ] work, [ ] emotions
[ ] Concentration, [ ] appetite, [ ] motivation, [ ] ADLs, [ ] IADLs
[ ] Other (specify)
- 9.
PATIENT’S PAIN GOAL (Check any appropriate boxes, if appropriate, and add brief descriptors of the patient’s goals regarding reduced level of pain intensity and goals related to function, ADLs, quality of life, etc.)
[ ] Sleep comfortably, [ ] comfort at rest, [ ] comfort with movement
[ ] Stay alert, [ ] perform activity (specify)
[ ] Other (specify)
Acceptable level of pain (0 to 10 scale):
- 10.
PAIN MEDICATIONS (During the interview, determine the current use, dosage, and general effectiveness of pain medications to determine the patient’s perception of effectiveness.)
- 11.
NONPHARMACOLOGIC METHODS OF PAIN RELIEF AND EFFECTIVENESS (For each method that the patient has used, note which pain sites are involved, past or present use, and effectiveness [yes/no].)
[ ] Physical therapy
[ ] Surgical interventions
[ ] Psychotherapy
[ ] Relaxation
[ ] Biofeedback
[ ] Manual treatments
[ ] TENS
[ ] Heat application
[ ] Cold application
[ ] Occupational therapy
[ ] Distraction
[ ] Exercises, [ ] stretching
[ ] Other (specify)
Relevant Medical History
Significant recent medical history
Psychosocial History and Present Status
Significant mental health and substance abuse history
Current employment status, current living arrangements
ADLs, activities of daily living; CPMC, Chronic Pain Management Clinic; IADLs, instrumental activities of daily living; TENS, transcutaneous electrical nerve stimulation.
Questionnaires and inventories provide opportunities for focused assessment of specific domains of functioning and quantifying patient responses. Because published questionnaires have typically met standards for reliability and validity, greater confidence can be placed in the information provided by these measures. Questionnaires typically permit quantification of important dimensions of the experience of pain and allow evaluation of within-person change over time. Concurrent administration of measures of multiple domains of functioning can assist in the identification of a patient’s relative strengths and weaknesses across these domains, such as identification of patients who report low levels of disability and distress despite an apparently severe level of pain intensity. Questionnaires with normative data offer the added benefit of providing a comparison point for evaluating the status of the respondent relative to others with similar painful conditions or within similar demographic groups (i.e., age, race/ethnicity, gender). Ultimately, they may provide a more efficient and cost-effective option to more intensive and time-consuming interviews. Following this brief overview of psychological and behavioral assessment strategies, a number of questionnaires and inventories that are frequently used for the assessment of patients with pain in the clinical setting are reviewed.
Diaries offer two advantages over other assessment methods. They allow recording of prospective, day-to-day, or even more frequent information about pain, sleep, and physical and emotional function, thereby eliminating the distortion associated with memory and retrospective recall. Additionally, diaries allow recording of the temporal association between pain and other factors. For example, many sleep diaries collect information about pain intensity scores before sleep, as well as sleep quality and duration. This allows investigation of the relationship between pain and functioning as opposed to examining either factor in isolation. The composition of diaries can vary from those designed to assess a single domain, such as pain intensity, to those that are much more comprehensive and multidimensional. The use of innovative technologies such mobile telephone applications, web-based diaries, and interactive voice response systems is increasingly being promoted as a more efficient strategy for collection of prospective information.
Although pain is a private, subjective experience, it is possible to observe signs that a patient is experiencing pain by direct behavioral observation . Patients can communicate that they are experiencing pain and the intensity of their pain through facial expressions, crying, moaning, limping, guarding, and rubbing affected areas. Behavioral observation of patients with chronic pain can provide valuable adjunctive information beyond that gathered with a self-report format and is crucial to the evaluation of those with cognitive or physical limitations that interfere with verbal communication. Behavioral observation methods have been developed for the assessment of patients with a range of painful medical conditions, including cancer pain, rheumatoid arthritis, osteoarthritis, and low back pain. Prkachin and colleagues reported on a method for assessment of pain behavior in the context of clinical evaluation of patients with low back pain. These methods have also been developed and used in studies of pain-relevant communication in partner dyads. To obtain reliable and valid behavioral observation data it is necessary to have a systematic plan for behavioral observation, coding, and interpretation of the data; accordingly, use of these methods requires considerable technological sophistication and expense. The use of behavioral observation methods is commonly limited to the clinical research setting because of the time-intensive and costly nature of these methods.
Reports of families and significant others in the assessment of pain have been strongly encouraged in contemporary models of pain, particularly Fordyce’s operant conditioning model and Turk’s cognitive-behavioral model, which have specifically encouraged this focus given the hypothesized roles of social contingencies in the perpetuation, if not etiology, of persistent pain and disability and awareness of the frequent negative impact of persistent pain on significant others. In particular, the role of solicitousness in the development and maintenance of pain-related disability has been a topic of a great deal of research. Operant principles specify that when spouses provide solicitous responses to pain behavior, the pain behavior is more likely to occur in the future, even in the absence of continued nociception. Positive or solicitous responses from spouses and family members, contingent on pain behavior, may serve to reinforce the maladaptive behavior and encourage the development and maintenance of pain and pain-related disability. Examples of solicitous behavior examined in the literature include expressions of sympathy or concern for the spouse, physical assistance or performance of a task, and encouraging rest and discouraging activity. A 2006 review summarized the evidence for relationships between marital functioning and chronic pain. In general, spouse solicitousness is significantly related to greater pain intensity, greater frequency of pain behavior, higher levels of disability, and increased help-seeking behavior. Distracting responses from significant others, meaning responses that are intended to cue engagement in other behavior in an effort to distract from pain, have been found to be positively related to poor outcomes despite the probable intent of these responses to encourage adaptive coping with pain. In addition to global measures of family and marital relationships, numerous questionnaires and inventories, diaries, and behavioral observation methods have been developed specifically for the assessment of pain-relevant communication and the impact of pain on family members and significant others.
Psychophysical measures are used primarily to demonstrate the influence of psychological factors on the initiation and maintenance of pain symptoms. For clinicians, psychophysical measures provide evidence that psychological factors are influencing biologic reactions in an individual patient and provide information on the utility of certain types of interventions (e.g., biofeedback). For the patient, evidence that psychological factors are influencing physical responses related to pain can provide direct feedback regarding the successful use of behavioral strategies to manage a pain disorder and increase confidence to engage in these behavioral strategies.
The most common clinical use of psychophysical measures in the treatment of pain occurs primarily during biofeedback treatments. Biofeedback treatments use psychophysical measures to train patients in voluntary modifications of bodily reactions through provision of feedback of physiologic processes. Surface electromyographic (EMG) recordings are the most widely used psychophysical measure in biofeedback for pain disorders because muscle tension is implicated in the majority of musculoskeletal pain disorders. EMG readings typically target specific muscle groups associated with the patient’s pain disorder (e.g., trapezius muscle for patients with upper back pain and the erector spinae muscle for patients with lower back pain). Additionally, blood flow is linked to several chronically painful conditions, including migraine headaches and Raynaud’s disease. For these conditions, measures of blood flow and peripheral skin temperature (a proxy for peripheral circulation) can be used in biofeedback treatments. Other types of biofeedback include heart rate variability and skin conductance, but more research is required to determine the relationship of these measures to chronic pain disorders and their utility in biofeedback treatment of chronic pain.
Specific Psychological and Behavioral Assessment Strategies
Standardized assessment instruments, often in the form of questionnaires or inventories, are used frequently in the assessment of patients with pain ( Table 16.1 ). Questionnaires allow a focused examination of a specific domain such as pain intensity, physical and emotional functioning, or coping beliefs and provide quantitative data that can be used to understand the patient’s functioning relative to the general population or other patients experiencing pain.
| Measure | Domain | Measure Details | Advantage/Disadvantages |
|---|---|---|---|
| Numerical rating scale (NRS) 31 ∗ | Pain intensity | Single item, written or oral | Demonstrated validity, easy to administer, high completion rate; use of a single item hinders reliability |
| Verbal rating scale (VRS) | Collection of pain descriptors | Demonstrated validity, easy to administer, high completion rate; may be difficult for persons with poor command of English | |
| Visual analog scale (VAS) | 10-cm line with descriptive end points | Demonstrated validity, easy to administer; more likely to be incomplete than the NRS or VRS, and use of a single item hinders reliability | |
| McGill Pain Questionnaire (MPQ) 32 ∗ | Pain quality | Collection of pain descriptors; also assesses location of pain and exacerbating and ameliorating factors | Demonstrated validity; not consistently associated with pain intensity but more consistently associated with psychological distress |
| Minnesota Multiphasic Personality Inventory, recently revised version (MMPI-2-RF) | Personality | 567 true-false items | Most widely used personality measure, uses normative data in scoring; high response burden, difficult to score, requires training to interpret, more information needed regarding validity for chronic pain |
| Millon Behavioral Health Inventory (MBHI) | 150 true-false items | Developed specifically for use in persons with medical conditions, demonstrated validity and reliability; high response burden, scoring time-consuming, not predictive of outcomes in treatment studies of persons with chronic pain | |
| West Haven–Yale Multidimensional Pain Inventory (WHYMPI) 35 ∗ (interference subscale) | Psychosocial impact | 52 items, assesses multiple domains | Demonstrated validity and reliability, useful for a variety of pain complaints, widely used; relatively high response burden, scoring time-consuming |
| Patient-Reported Outcomes Measurement Information System (PROMIS) (pain-interference and pain-behaviors item banks) | Item banks (interference = 41 items; behaviors = 39 items) | Standardized bank of items developed by the NIH, demonstrated reliability and initial validity, available in short forms; more information regarding validity needed | |
| Sickness Impact Profile (SIP) | 136 items and 24-item brief version for persons with chronic back pain | Demonstrated validity and reliability, responsive to change; full version has high response burden | |
| Pain Disability Index (PDI) | Physical/social role function | 49 items, assesses perceived disability in 7 areas | Demonstrated validity and reliability, can identify specific areas of perceived disability; relatively high response burden, scoring time-consuming |
| Brief Pain Inventory (BPI) 40 ∗ | 32-items, short form has 15 items, ultra-brief version (PEG) has 3 items | Widely used, demonstrated validity and reliability, easy to administer, brief versions appropriate for multiple clinical settings; further validity information for PEG warranted | |
| Beck Depression Inventory (BDI) 41 ∗ | Emotional function | 21 items, measures depression | Demonstrated reliability and reliability, sensitive to change; somatic items may be associated with pain rather than mood, possible bias in certain populations |
| Center for Epidemiologic Studies Depression Scale (CES-D) | 20 items, measures depression | Demonstrated reliability and validity in a wide variety of ethnic populations, non-English version available; lacks sensitivity and specificity without psychiatric interview | |
| Geriatric Depression Scale (GDS) | 30 yes-no questions, measures depression in older adults | Demonstrated reliability and validity, good sensitivity and specificity; has not yet been widely used in chronic pain samples | |
| Pain Anxiety Symptoms Scale (PASS) | 53 items, assesses pain-related fear | Demonstrated validity; poor prediction of pain-related disability, relatively high response burden | |
| State-Trait Anxiety Inventory (STAI) | Two 20-item measures of state and trait anxiety | Acceptable psychometric properties, widely used, sensitive to change | |
| Profile of Mood States (POMS) | 65-item measure of several dimensions of emotional functioning | Strong psychometric properties, sensitive to change, captures negative and positive dimensions of emotional functioning; high response burden | |
| Symptom Checklist—90 Revised (SCL-90R) | 90-item measure of numerous areas of psychological functioning | Demonstrated reliability and validity; normed on psychiatric patients and may not be valid for use in persons with chronic pain, high response burden | |
| Medical Outcomes Study Short Form Health Survey (SF-36) | 36-item measure of perceived physical and emotional health | Psychometrically sound, widely used; has not yet been widely used in chronic pain samples | |
| Survey of Pain Attitudes (SOPA) | Pain beliefs and coping | 57-item measure of pain-related beliefs; brief forms also available | Psychometrically sound, scores correlated with treatment outcomes and physical and emotional functioning |
| Pain Stages of Change Questionnaire (PSOCQ) | 30-item measure of readiness to change | Demonstrated reliability and validity, predicts completion of treatment, changes in PSOCQ predict changes in “readiness”; may not be predictive of treatment outcomes | |
| Chronic Pain Coping Inventory (CPCI) | 64-item measure of use of pain-coping strategies | Psychometrically sound, patient coping strategies found to be associated with outcomes; high response burden | |
| Pain Catastrophizing Scale (PCS) | 13-item measure of pain-related catastrophic thoughts | Psychometrically sound, associated with treatment outcomes; further evaluation in clinical samples warranted | |
| Chronic Pain Acceptance Questionnaire (CPAQ) | 20-item measure of pain acceptance; 8-item brief form also available | Demonstrated reliability and cross-sectional validity; associated with treatment outcomes, measure is specific to a single type of pain treatment, and further information regarding predictive validity is warranted | |
| Patient Outcome Questionnaire (POQ) | Quality of care | 12-item measure of perceived quality of pain treatment | Commissioned by the American Pain Society, demonstrated reliability and internal validity; additional validity studies are needed |
∗ Measure was selected by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) panel as the preferred measure within a domain.
Pain Intensity
A primary objective in assessing patients experiencing pain is to determine their level of pain intensity. Change in pain intensity from baseline to after treatment is often the primary outcome measure used in evaluating the efficacy of a given pain treatment. The following measures attempt to quantify the private experience of perceived pain. The numerical rating scale (NRS), the verbal rating scale (VRS), and the visual analog scale (VAS) are the most frequently used measures of pain intensity .
The NRS is a single-item rating scale of pain intensity that can be administered in an oral or written format. Patients are asked to specify their pain on a scale from 0 to 10, with 0 representing “no pain” and 10 representing “the worst pain imaginable” or extreme pain. Although a 0 to 10 scale is most commonly used, ranges of 0 to 20 or 0 to 100 are also used. Farrar and colleagues suggested that a 2-point decrease in the 0 to 10 NRS may be indicative of a clinically important change in pain intensity. Advantages of the NRS include ease of administration and scoring and high rates of completion by respondents.
The VRS contains a list of pain descriptors that typically range in intensity from “no pain” to “severe pain.” Patients select the descriptor that best characterizes their level of pain from a list that ranges from 4 to 15 descriptors. The descriptors are then assigned a number value based on the intensity level (i.e., no pain = 0, mild = 1, moderate = 2, and severe = 3). Like the NRS, the VRS has demonstrated validity through significant correlations with other measures of pain intensity. Although the VRS is an attractive option because it is easy to administer, patients with limited vocabulary or command of English may have difficulty discriminating among the descriptor words, and the selection of descriptors may not adequately describe a respondent’s pain, especially when a four-descriptor format is used.
The VAS uses a 10-cm-long line with end points denoting the absence of pain (e.g., “no pain”) at one end and extreme pain at the other. Respondents place a mark on the line at the point that best characterizes their pain intensity relative to the end points. Calculation of a pain intensity score is based on the distance from the “no pain” end point to the respondent’s mark.
A review by Jensen and Karoly found that all the aforementioned measures demonstrated validity through significant correlations with other pain intensity measures and have comparable responsiveness to changes in pain in the context of pain treatment. Evidence suggests that respondents may prefer VRS and NRS instruments over the VAS and that VAS instruments are more likely than NRS measures to result in missing or incomplete data, possibly because of cognitive or motor disabilities. For these reasons, the consensus statement of the IMMPACT committee’s review of core measures for chronic pain clinical trials recommends using an 11-point NRS scale to assess pain intensity and the VRS as an adjunct. Although these recommendations were developed for use by clinical researchers, the importance of consistent use of valid, reliable, and understandable measures in clinical practice should not be ignored, and the guidelines provide valuable information for all users of these measures.
The McGill Pain Questionnaire (MPQ) is a more lengthy measure designed to assess the quality and affective component of the pain experience, not simply pain intensity. Respondents choose pain descriptors from a list of 78 potential descriptors that fall into 20 pain categories. These descriptors assess four pain domains: sensory, affective, evaluative, and miscellaneous. Within each category the individual descriptors reflect varying degrees of intensity and are assigned corresponding numerical values that reflect this difference. Respondents also highlight the location of their pain on a figure drawing and provide information about the factors that alleviate and aggravate their pain intensity. The MPQ generates three scores: (1) the Pain Rating Index, which is the sum of all words chosen in the available categories (the sum of the value of each subclass can also be obtained); (2) the number of words chosen, a score that reflects the number of words chosen from each of the four categories; and (3) the present pain intensity, a rating of current pain on a scale from 0 (no pain) to 5 (excruciating). The MPQ has been widely used in a variety of pain-focused research and has been translated into several languages, although not all new versions of the scale have been subjected to adequate clinimetric or psychometric testing. A 15-item short-version of the MPQ (SF-MPQ) is also available.
Strengths of the MPQ include demonstrated validity of its subscales through their association with perceived quality of life, ability to discriminate among pain conditions, pain medication use, and sensitivity to the effects of pain treatment. The MPQ scale scores have not shown a consistent association with pain intensity ratings, and a review concluded that the MPQ scales may not measure the same construct as other pain intensity measures do and may be less sensitive than “pure” measures of pain intensity such as the NRS and VRS. The SF-MPQ demonstrated high correlation with the Pain Rating Index of the MPQ and was sensitive to changes produced by pain medications in patients with pain. The IMMPACT committee recommended use of the SF-MPQ as a measure of pain quality and the affective component of pain because these aspects of the pain experience may respond differently to treatment than pain intensity does.
Personality
The Minnesota Multiphasic Personality Inventory (MMPI) is by far the most commonly used objective measure of personality, and it is similarly the most commonly used measure for the evaluation of psychological functioning of patients with pain. A recently revised version, known as the MMPI-2-RF, consists of 338 true-false items that are used to derive scores on: 3 higher-order scales; 9 restructured clinical scales; 8 validity scales; 14 somatic/cognitive and internalizing scales; 11 externalizing, interpersonal, and interest scales; and 5 personality psychopathology scales. The most recent version of the MMPI has several advantages over previous versions: it is based on more modern views of psychopathology, it has fewer items and therefore lower patient burden, and its normative sample is more representative of the U.S. population. Additionally, the restructured clinical scales have reduced intercorrelations with respect to the original scales and have demonstrated validity in predicting pathology with more accuracy while using fewer items than the original scales. However, the MMPI-2-RF has not been examined in patients with chronic pain.
Significant concerns have been raised about the appropriateness of the previous versions of the MMPI (MMPI or MMPI-2) for use in the assessment of patients with chronic pain. Differences observed on the clinical scales between pain and nonpain samples have been demonstrated to more likely reflect disease status than psychological functioning. An extensive research effort has focused on the identification of reliable subgroups of patients with chronic pain based on their MMPI profiles. The sum of this literature suggests that even though reliable subgroups can be identified despite evidence that the subgroups differ in terms of behavioral correlates of the experience of pain, it has yet to be demonstrated in a compelling fashion that the MMPI has value in characterizing patterns of coping with chronic pain over and above data derived from pain-specific measures. No information is available to indicate whether these issues have been alleviated (or exacerbated) by the significant revisions of the MMPI-2-RF. Results in patients with chronic pain should be interpreted with caution until further studies are able to validate the MMPI-2-RF in chronic pain populations.
The Millon Behavioral Health Inventory (MBHI) was developed to assess the psychological functioning of patients with medical conditions. This 150-item measure contains eight scales designed to assess the respondent’s interaction style (e.g., cooperation), six scales that assess the respondent’s response to illness (e.g., pain treatment responsivity), and six scales that assess the presence of psychosocial stressors (e.g., social alienation). Questions are posed in a true/false format. A respondent’s answers are scored by comparison with the base rate in the normative sample, which consisted of patients with a variety of medical illnesses.
The MBHI has been demonstrated to have substantial reliability and validity indices. It may have advantages relative to the MMPI-2-RF for use in the assessment of patients with pain conditions as a function of its relative brevity and the fact that it was developed and normed on medical as opposed to psychiatric populations. However, to date, studies have failed to demonstrate the predictive validity of the scale in studies of psychological interventions, surgical interventions, or multidisciplinary treatment of patients with chronic pain.
Assessment of Psychosocial Impact
The West Haven–Yale Multidimensional Pain Inventory (WHYMPI) is designed to measure the psychosocial and behavioral aspects of chronic pain and is useful across a variety of pain complaints. It is a 52-item multidimensional self-report instrument that uses 7-point Likert scales. The instrument consists of three sections. Section one includes six scales measuring pain-related interference across several domains, including work and leisure activities, as well as interpersonal relationships, perceived support from spouse or significant other, pain severity and suffering, perceived life control, and negative mood. Section two assesses patient perception of significant others’ responses to overt expressions of pain by classifying responses as solicitous, distracting, or negative. Section three measures the frequency with which the patient engages in four clusters of everyday activities, including household chores, social activities, outdoor work, and activities away from home. The WHYMPI takes approximately 10 to 15 minutes to complete and is written at a fifth-grade reading level. Test-retest reliability over 2 weeks ranges from 0.62 to 0.91, and internal reliability coefficients range from 0.70 to 0.90. Several investigative teams have generally replicated the factor structure and psychometric properties of the WHYMPI. Turk and colleagues proposed an empirically derived taxonomy of the WHYMPI that includes three reliable profiles of patients with persistent pain labeled as dysfunctional, interpersonally distressed, and adaptive copers, and these investigators and several other groups have replicated these findings in numerous samples of patients with various pain conditions. The measure has been used in many empirical studies, including clinical trials of psychological and pharmacologic interventions, studies of the psychosocial impact of pain, and studies examining the role of psychosocial factors as contributors to the development and maintenance of persistent pain. The IMMPACT group recommended use of the interference scale of the WHYMPI as an outcome measure in pain clinical trials. The second section of the measures that focus on responses of significant others has been particularly valuable in evaluating the role of such responses as predictors of the severity of pain and pain-related disability and distress.
Three additions to the original version of the scale have enhanced its overall reliability, validity, and clinical utility. Rudy added two items to the life control and interference scales, Okifuji and colleagues proposed alternative instructions for the significant other response section to reduce missing observations, and Bruehl and colleagues developed a scale to detect random responding and malingering. A significant other version of the measure has also been published.
The National Institutes of Health Patient-Reported Outcomes Measurement Information System (PROMIS) is a standardized item bank developed by a cooperative group for the purpose of developing psychometrically sound standardized measures to assess patient-reported outcomes. These measures provide information on the domains of physical, mental, and social health across a variety of medical illnesses. Measures for pain currently available in the PROMIS assessment center ( www.assessmentcenter.net ) include “pain-interference” and “pain-behaviors.” The pain-interference item bank includes 41 items, with 4 short forms consisting of 4 to 8 items. The pain-behaviors item bank includes 39 items with a single short form consisting of 7 items. Both measures have demonstrated reliability and validity in psychometric evaluation, were related to other measures of pain-related outcomes, and discriminated among groups of patients with different self-reported health, number of chronic conditions, and number of disabling conditions. Further studies have demonstrated that pain-related measures are higher and global scores of quality of life are lower in clinical pain samples than in samples from the general population. The PROMIS pain-interference and pain-behaviors scales have recently been developed and therefore have only a small body of evidence regarding reliability and validity. Available studies suggest that these scales provide comprehensive, sophisticated, and psychometrically sound measures for pain-related patient-reported outcomes.
The Sickness Impact Profile (SIP) measures the degree of disability across 12 domains of functioning. One hundred thirty-six items are used to derive measures of sleep and rest, eating, work, home management, recreation and pastimes, ambulation, mobility, body care and movement, social interaction, alertness behavior, emotional behavior, and communication. These domain scores are combined to produce physical, psychosocial, and total disability scores. The SIP can be self-administered or administered by an interviewer in about 20 to 30 minutes.
An extensive period of development and testing and reports on these efforts support the reliability and validity of the measure. The SIP has been found to be responsive to change during treatment of chronic pain. A brief version consisting of 24 items, called the Roland-Morris Disability Questionnaire, has been developed specifically for use in patients with chronic low back pain. This measure has also been shown to have strong evidence of reliability, validity, and responsiveness to change as a function of psychological interventions and is recommended by the IMMPACT group as the preferred measure of physical functioning for evaluating persons with back pain.
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