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.
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.