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Pain Assessment: Review of Current Tools

Health care professionals who treat pain require objective measures that incorporate both emotional and sensory aspects of a patient’s pain experience. This is far from an easy task.

Pain is inherently subjective and could be considered an emotional response to a personal experience. In fact, emotional suffering is an important and perhaps underappreciated aspect of persistent pain.1 At the same time, pain is ubiquitous and familiar to everyone and remains one of the most common reasons that Americans access the health care system.2

Acute pain tends to be more straightforward to quantify than chronic pain. Monitoring the time to reaction from various levels of noxious stimulation in the experimental setting can provide an objective measure for both humans and animals. In chronic pain, however, there is frequently no apparent noxious stimulus. It’s typically measured either based on the patient’s self-report or on observation of the patient’s behaviors, which may lead to unreliable results.3

Current Pain Metrics

Regular pain assessments are an important part of chronic pain therapy. The ideal pain assessment tool would produce a numeric score or other objective metric, be easy to administer, be readily understood by patients, and yield reproducible results with good specificity and sensitivity. A number of clinically tested and validated pain scales exist (click here for a full listing).4-28

Among the most frequently used pain scales in the US is the visual analog scale (VAS).29 When using the VAS, the patient is shown a 100 mm line and asked to point to the area of the line that describes his or her pain, with the left end of the scale meaning “no pain” and the right end “the worst pain imaginable.” The best-known pediatric pain scale is the Wong-Baker FACES scale, in which the child is shown 6 faces—from a smiling happy face to a vigorously crying face—and is asked which face best represents his or her current level of pain.20

Pain manifests itself in numerous ways (functional limitations, emotional symptoms, physical sensations, and behavioral changes), and the clinician should be careful to choose the pain assessment tool that most closely corresponds to the patient’s symptoms and conditions. This in itself can cause confusion as pain scales are not interchangeable—a rating of 10 on one scale may not be equivalent to the same score on another. What’s more, pain scales may not only measure pain intensity but factor in aspects that change over time, including functional limitations, emotional considerations, and behavior.

To establish these measures, pain scales rely on either patient self-report, a health care professional, or, in some cases, a parent, family member, or caregiver. Self-reports may or may not be consistent over time but have been validated in many studies of pain assessments.

The language of pain is crucial to its reliable evaluation. Longer, more comprehensive descriptions of pain may be easier for the patient to grasp and categorize than pain descriptors, such as “moderate pain” or “pain that is getting worse.”

It may also be clinically meaningful to evaluate pain not in terms of pain intensity but rather in terms of how much and in what ways that pain interferes with function. For instance, a chronic pain patient may find it more relevant to be able to sit through a movie comfortably than to drop 1 point on a numeric rating scale. Pain scales may further neglect emotional components of pain and symptoms of mental distress, such as depression, anxiety, and stress.

Despite laudable efforts to develop metrics that accurately and consistently measure pain levels over time, none of the many tools available achieve this task perfectly. For that reason, the Indiana Polyclinic Combined Pain Scale (IPCPS) was developed 15 years ago to offer the breadth required by certain chronic pain patients, the simplicity necessitated by a hectic clinical practice, and the versatility to accommodate a wide range of patients.

New Assessment Scales

The IPCPS consists of a combined pain scale, combined function scale, combined depression scale, and the combined anxiety scale (see Tables 1-4). The new assessment tools, which were developed by the authors, attempt to account for the full spectrum of the pain experience and may provide a more accurate way of assessing and documenting chronic pain.

Download Table 1 PDF

Download Table 2 PDF

Download Table 3 PDF

Download Table 4 PDF

How IPCPS Measures Pain Intensity

IPCPS rates pain intensity on the familiar 11-point scale with 0 meaning “no pain” and 10 “the worst possible pain imaginable.” However, more prominent than the numbers on the scale are clear definitions of various pain states. With these added descriptions, along with examples, pain patients may be better able to contextualize and evaluate their own pain intensity experiences.

The initial report is completed by the patient without assistance from the health care team. During the appointment, the clinician reviews the completed form with the patient (and any accompanying persons). Everyone is free to ask questions. With some discussion and clarification, the patient can gain an improved understanding of the pain intensity score and may revise his or her original report to eliminate unnecessary errors or inappropriately high or low reported scores.

Because pain intensity can fluctuate in chronic pain patients, it is important for clinicians to evaluate pain with IPCPS frequently and consistently.

How IPCPS Incorporates Functional Impairment

Chronic pain interferes with function and can, in turn, affect the patient’s well-being, independence, and ability to pursue the normal activities of daily living. One standard measurement of function has been the Functional Independence Measure (FIM), an 18-item questionnaire that describes 13 motor functions (including eating, grooming, and bathing) and 5 cognitive functions (including expression, social interaction, and memory), which patients rate individually on a scale of 0 to 7.30 The higher the score, the more independent the patient is in performing that task. The FIM scale requires that the clinician be trained in its use and observe the patient as he or she performs specific tasks.

The IPCPS uses a modified FIM scale, allowing it to work well for a wide range of conditions and remain consistent with the pain intensity portion of the IPCPS. The FIM scale was changed from the original 0 to 7 scale to an 11-point scale with 0 meaning “perfect function” and 10 “complete disability.” Patients are also allowed to self-report their ratings rather than have a health care professional evaluate their performance. As with the pain intensity scale, each number is described in words so that the patient can contextualize his or her functional limitations.

How IPCPS Incorporates Depression and Anxiety

Shame, guilt, humiliation, embarrassment, and mental defeat are categorized as “self-conscious emotions,” and are significantly more common among chronic pain patients compared to control patients.31 Such self-conscious emotions exacerbate pain intensity levels, and mental defeat is significantly related to disability.31 Catastrophizing can also worsen chronic pain conditions.32

Meanwhile, chronic pain patients who are asked to quantify their internal experiences can overestimate their depressive symptoms.33 In addition to items related to depression and anxiety in pain rating scales, there are validated assessment tools that can be used to specifically measure those symptoms. However, these rating systems are sometimes complex or require a specially trained clinician to conduct the test.34

Reporting depression and anxiety scores in a VAS format allows the patient to be evaluated frequently over a period of time, which allows for a series of scores that can provide insight into progression of symptomatology, pain, and treatment results.35 Because VAS scores are numerical, they avoid literacy, linguistic, or cultural barriers that may arise when clinicians attempt to get patients to describe their state of mind.36 Overall, VAS tests are simple, easy to administer, quick, inexpensive, and practical for real-world busy clinics with diverse patient populations.37

The Indiana Polyclinic team aimed to set the metric for the emotional component of the rating scale so that it could accurately classify depression and anxiety in a way that would allow the patient to correctly and objectively self-report his or her emotional status. Although anxiety and depression are both mental health conditions that can impact pain, they require separate scales as they are fundamentally different states.

It is important to recognize that the diagnosis of major depressive disorder (MDD) does not require that the patient feel depressed. Anhedonia along with other symptoms such as fatigue and decreased concentration suffice for an MDD diagnosis. For that reason, “joy of life” was added to the questionnaire to help better identify patients experiencing some degree of anhedonia.

The Use of IPCPS in Practice

The IPCPS consists of 4 test instruments of similar design, each offering both verbal descriptions and numeric ratings for patients. Based on experience at the Indiana Polyclinic over the past 15 years, it is most useful to administer all 4 tests to complex and chronic pain patients, even those who do not seem particularly depressed or who do not show noticeable degrees of functional impairment. While these test instruments may appear verbose at first glance, they become familiar to the patient after the first few uses. Patients can then rate these four aspects of their life (pain intensity, function, depression, and anxiety) in a matter of minutes. The textual descriptions of the various ratings may also serve as springboards for more in-depth discussions about the patient’s experiences.

Further study is needed to validate IPCPS and compare it with more established pain scales (All scales are available for download)

Addiction Monitoring Tool for Chronic Pain

The risks and benefits of long-term opioid therapy for chronic pain management can evolve over time. Personal or family history of addiction is a common continual risk associated with potential abuse and addiction, while psychosocial issues as well as comorbid medical and mental health conditions may be dynamic factors.38

The Screening Tool for Addiction Risk (STAR) was developed to assess for potential aberrant behaviors in patients starting long-term opioid therapy.39 The STAR is intended to be used prior to the initiation of long-term opioid treatment and does account for various psychosocial factors as well as other substance-related risks.39 Some of the questions in the original version of the STAR limit continual assessment of psychosocial factors. Other important questions pertaining to more serious aberrant behaviors are also missing.40

Thus, with permission of the developers of the STAR, the Indiana Polyclinic, in Indianapolis, created a modified version to account for potential changes that may occur during the course of long-term opioid therapy, as well as illegal behaviors. The STAR-IPC revision contains a total of 15 questions, is easy to score, and takes less than 5 minutes to complete (Table 5). When used in combination with other risk management strategies, it can help highlight potential risks, recommend changes in the level of monitoring practices, or justify referrals for addiction treatment or ceasing opioids altogether.

Download Table 5 PDF

There are several limitations to the STAR-IPC version. It is not intended to be a lie detector and should not be used without additional monitoring strategies, such as drug screens, communication with other providers and the patient’s relatives, inspection of medical records, and PDMPs. The revised version has not been validated and requires additional studies. It may be further improved by adding a question about the use of benzodiazepines.

Acknowledgements: The author wishes to thank Jo Ann LeQuang and Scott de Long of LeQ Medical in Angleton, Texas, who helped with editing and proofreading this manuscript. The author is also grateful to Teresa Hall, OT, for her crucial contributions in developing the scales presented in this article. Adam Goff, BA, analyzed available depression and anxiety scales with corresponding bibliography. Critiques from Bruce Durell, MD, and Linda Prokai, PA-C, helped in the shaping of the scales. He also thanks Paul Adams for his editorial assistance and John Wiedelman for making the scales presentable.

Last updated on: April 29, 2019
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