Chronic Pain Assessment Scales

“Please rate your pain from one to ten,” the doctor says. That statement is the bane of every chronic pain patient’s existence. Pain, regardless of the type or location in the body, is a subjective experience. Some have higher thresholds for pain than others. Chronic pain assessment scales are used by medical professionals, parents, and caregivers to assess pain.

Chronic Pain Assessment

What is Chronic Pain?

Pain is the body’s natural response to illness or injury. Spinal nerves within the central nervous system deliver messages to the brain that warn the body of damage. This creates a pain response that can be felt as burning, sharp, dull, or aching sensations. Once the body heals, the pain dissipates.

In some cases, pain occurs without trauma or persists after the body heals. Chronic pain is pain that lasts longer than twelve weeks. It continues for months to years. The CDC reports that approximately one and five adults in the United States experience chronic pain. It can result from work-related injuries, fibromyalgia, arthritis, multiple sclerosis (M.S.), endometriosis in females, interstitial cystitis, and more.

What is a Pain Scale?

Pain is a subjective experience. No two patients feel identical sensations. Pain assessment scales help give physicians, parents, and caregivers an objective measurement of pain, its type, and severity. The scales are often applied in medical settings. They assist in diagnosing medical conditions, tailoring treatment plans, and monitoring the effectiveness of therapies (i.e. medications, physical therapy, etc.).

There are a variety of pain scales for specific purposes and patient populations. For example, infants and nonverbal adults do not rate their pain on the same scale as the typical verbal adult or adolescent.

Chronic Pain Assessment Scales: Numerical Rating Scale (NRS)

The Numerical Rating Scale (NRS) requires the patient rate their pain on a 0 to 10 scale where “0” is no pain and “10” is the worst pain imaginable. Although still subjective, numbers are the easiest assessment tool that saves time. This unidimensional scale does not consider emotional factors that worsen a patient’s pain, nor does it offer descriptions.

For patients to visualize the scale, it is presented as a horizontal segmented bar including the numbers 0 to 10. Only “0,” “5,” and “10” have labels ranging from no pain, moderate pain, and worst possible pain.

Chronic Pain Assessment Scales: Visual Analog Scale

The Visual Analog Scale is similar to the Numerical Rating Scale excluding the numbers. Patients rate their pain by making a mark on a horizontal line. The beginning of the continuum represents “no pain” and the end “worst pain.” There are no images or descriptions. It provides a visual depiction in which to rate pain.  

Chronic Pain Assessment Scales: Stanford Pain Scale

The Stanford Pain Scale is a more thorough version of the Numerical Rating Scale. Like the Numerical Rating Scale, the Stanford Pain Scale ranges from 0 to 10. However, the ratings are also categorized by color and descriptions. The descriptions are very detailed.

A pain rating between 1 and 3 is in green and classified as minor. Minor pain “does not interfere with most activities. The patient is able to adapt to pain psychologically and with medication devices such as cushions.”

  • 1: Very Mild—Vert light barely noticeable pain, like a mosquito bite or a poison ivy itch. Most of the time you never think about the pain.
  • 2 Discomforting—Minor pain, like lightly pinching the fold of skin between the thumb and first finger with the other hand, using the fingernails. Note that people react differently to this self-test.
  • 3 Tolerable—Very noticeable pain, like an accidental cut, a blow to the nose causing a blood nose, or a doctor giving you an injection. The pain is not so strong that you cannot get used to it. Eventually, most of the time you don’t notice the pain. You have adapted to it.

A pain rating falling between 4 and 6 is yellow and classified as moderate. Moderate pain “interferes with many activities. Requires lifestyle changes but patient remains independent. Unable to adapt to pain.”

  • 4: Distressing—Strong, deep pain, like an average toothache, the initial pain from a bee sting, or a minor trauma to part of the body such as stubbing your toe. You notice the pain all of the time and cannot completely adapt. This pain level can be stimulated by pinching the fold of the skin between the thumb and first finer with the other hand, using the fingernails, and squeezing hard. Note how the stimulated pain is initially piercing but becomes dull after that.
  • 5: Very Distressing—Strong, deep, piercing pain such as a sprained ankle when you stand on it wrong or mild back pain. Not only do you notice the pain all of the time, you are now so preoccupied with managing it that your normal lifestyle is curtailed. Temporary personality disorders are frequent.
  • 6: Intense—Strong, deep, piercing pain so strong it seems to partially dominate your senses causing you to think somewhat unclearly. At this point, you begin to have trouble holding a job or maintaining normal social relationships. Comparable to a bad non-migraine headache combined with several bee stings, or bad back pain.

A pain rating falling between 7 and 10 is red and classified as severe. Severe pain is described as “unable to engage in normal activities. Patient is disabled and unable to function independently.”

  • 7: Very Intense—Same as 6 except the pain completely dominates your senses, causing you to think unclearly about half of the time. At this point, you are effectively disabled and frequently cannot live alone. Comparable to an average migraine headache.
  • 8: Utterly Horrible— Pain so intense you can no longer think clearly and have often undergone severe personality change if the pain has been present for a long time. Suicide is frequently contemplated and sometimes attempted. Comparable to childbirth or a migraine headache.
  • 9: Excruciating Unbearable—Pain so intense you cannot tolerate it and demand pain killers or surgery, no matter the side effects or risk. If this doesn’t work, suicide is frequent since there is no more joy in life whatsoever. Comparable to throat cancer.
  • 10: Unimaginable Unspeakable—Pain so intense you will go unconscious shortly. Most people have never experienced this level of pain. Those who have suffered a severe accident, such as. Crushed hand, and lost consciousness as a result of the pain and not blood loss, have experienced level 10.

Chronic Pain Assessment Scales: Brief Pain Inventory

The Brief Pain Inventory is a self-report pain scale offered in both a long and short form. The scale is in an interview format. Patients evaluate the severity of their pain, how pain effects daily activities, the location of pain, and monitoring of pain medications. On average, the Brief Pain Inventory takes 5 to 10 minutes to administer. It is optimal for adults.

The survey contains a series of “yes” or “no” questions, as well as rating various factors of pain on a 0 to 10 scale. Patients are directed to shade the areas of the body they feel pain on a diagram of the human body.

Chronic Pain Assessment Scales: Global Pain Scale

The Global Pain Scale assesses physical, sociocultural, and psychological aspects of pain. Also in a survey format, the Global Pain Scale is divided into multiple parts.

The first section is Pain. Patients must rate the following statements from 0 to 10—“0” being no pain and “10” being extreme pain.

  • My current pain is…
  • During the past week, the best my pain has been is…
  • During the past week, the worst my pain has been is…
  • During the past week, my average pain has been…
  • During the past 3 months, my average pain has been…

Patients then rate how frequently they have felt certain emotions within the past week on a 0 to 10 scale. In this instance, “0” means strongly disagree and “10” means strongly agree. The emotions are: Afraid, Depressed, Tired, Anxious, and Stressed.

Since pain interferes with daily functioning, patients also rate functions and activities impacted by their pain on the same 0 to 10/strongly disagree and/or strongly agree scale:

  • I had trouble sleeping…
  • I had trouble feeling comfortable…
  • I was less independent…
  • I was unable to work…
  • I needed to take more medication…
  • Go to the store…
  • Do chores in my home…
  • Enjoy my friends and family…
  • Exercises (including walking)…
  • Participate in my favorite hobbies…

To calculate the pain reading, add the total score and divide it by 2. Each of these four areas is a total of 25 points with a maximum score of 100.  

Chronic Pain Assessment Scales: McGill Pain Index

The McGill Pain Index originated in 1971. It was developed by Melzack and Torgerson at McGill University. The scale is visually represented as a vertical bar that begins at 0 and increases to 50 in increments of 10. The higher the number, the more severe the pain. Pain levels are compared to various injuries assigned by numbers of the scale:

  • Fracture
  • Phantom limb pain
  • Nonterminal cancer
  • Chronic back pain
  • Prepared childbirth
  • Unprepared childbirth
  • Amputation of digit
  • Complex Regional Pain Syndrome (RSD/CRPS)

Chronic Pain Assessment Scales For the Critically Ill and Non-Verbal

Adult patients who are critically ill and/or non-verbal cannot depend on traditional pain rating scales which rely on patient-reports. In these instances, medical professionals and caregivers have to perform the pain assessment without the patient’s input. Patients are non-verbal for numerous reasons like an intellectual disability, dementia, or a severe illness requiring mechanical ventilation. Regardless of the cause, researchers have developed chronic pain scales for non-verbal cases specifically.

Behavioral Pain Scale

The Behavioral Pain Scale was developed to evaluate intubated patients. Assessments are based on the patient’s body language. For professionals to use the Behavioral Pain Scale, they judge the patient’s facial expressions, limb movements, and how well they are tolerating ventilation. The sum of the scores determine the patient’s pain level.

  • Facial expressions—Relaxed (1 point), Partially tightened (2 points), Fully tightened (3 points), Grimacing (4 points)
  • Upper lib movements—No movement (1 points), Partially bent (2 points), Fully bent with finger flexion (3 points), Permanently retracted (4 points)
  • Compliance of mechanical ventilation—Tolerating movement (1 point), Coughing but tolerating ventilation for most of the time (2 points), Fighting ventilator (3 points), Unable to control ventilation (4 points)

Experts tested the accuracy of the scale by documenting patient responses after performing procedures that are generally not painful like a central line dressing change, as well as painful procedures.

Adult Non-Verbal Pain Scale

The adult Nonverbal Pain Scale is warranted in situations where the patient is unable to speak. It is primarily used in patients with mechanical ventilation or in advanced dementia. Pain is measured by body language like in the Behavioral Pain Scale. The sum of points equals the patient’s pain level. Any score above 3 suggests the need for pain control.

The American Journal of Critical Care proposes the assessment criteria:

  • Face—No expression or smile (0 points), Occasional grimace, tearing, frowning, or wrinkled forehead (1 point), Frequent grimace, tearing, frowning, or wrinkled forehead (2 points)
  • Activity—Lying quietly, normal position (0 points), Seeking attention through movement or slow, cautious movement (1 point), Restless excessive activity and/or withdrawal reflexes (2 points)
  • Guarding—Lying quietly, no positioning of hands over areas of the body (0 points), Splinting areas of the body, tense (1 point), Rigid, stiff (2 points)
  • Vital signs—Baseline vital signs unchanged (0 points), Change in systolic blood pressure greater than 20 or an increase in heart rate greater than 20 beats per minute (1 point), Change in systolic blood pressure greater than 30, or an increase in heart rate greater than 25 beats per minute (2 points)
  • Respiratory—Baseline respiration rate synchronous with ventilator (0 points), Increase in respiratory rate greater than 10 breaths per minute over baseline, 5% decreases of SpO or mild ventilator asynchrony (1 point), Increase in respiratory rate greater than 20 breaths per minute over baseline, 10% decreases of SpO or severe ventilator asynchrony

Critical Care Observation Tool

Comparable to the other pain scales used for non-verbal patients, the Critical Care Observation Tool evaluates facial expressions, body movement, ventilator compliance, vocalization, and muscle tension. Medical professionals or caregivers monitor the patient for at least one minute to determine the patient’s baseline pain levels. According to McGill University, the patient should be evaluated during procedures, and before and after treatment. Muscle tension is best evaluated last, as movement of the muscles can provoke behavioral changes.

Chronic Pain Assessment Scales For Pediatric Patients

Pediatric patients have a limited understanding of pain. While pain scales for young children and adolescents contain some elements of adult pain-rating scales, the explanations are simplified. Additionally, infants and toddlers are mostly non-verbal and are unable to vocalize their pain to their doctors or caregivers. Creating pain scales specifically for pediatric patients overcomes this barrier. The pain scales for infants mainly rely on observing physiological and behavioral responses.

Wong-Baker Faces Scale

The Wong-Baker Faces Scale is intended for those aged 3 or older. The scale includes 6 images of faces. The first face is depicted to have a wide smile and represents a pain level of 0. Each face is altered in expression. The second face is a pain level of “2”  “hurts a little bit.” The third face is a pain level of “4” that “hurts a little more.” The fourth face is a pain level of “6” and indicates “hurts even more.” The fifth and sixth faces are severe pain with levels of “8” and “10” and describe the pain as “hurts a whole lot” and “hurts worse.”

Although it was created for children because the cartoon faces are kid-friendly and easy to understand, adults can use this scale.

Neonatal/Infant Pain Scale

The Neonatal Infant Pain Scale (NIPS) records behaviors, expressions, and physiological responses of infants less than one year of age to judge their pain levels. The score serves as guidelines for administering medication. Mild pain may only indicate non-pharmacologic options such as repositioning or swaddling, but moderate to severe pain can require narcotic pain medications. The behaviors observed for one minute and consist of facial expressions, cry (i.e. no cry, whimper, vigorous cry), breathing patterns, arms, legs, and state of arousal (i.e. sleeping/awake, fussy). These behaviors are rated with 0 or 1. However, the rating options for “cry” go up to 2.

Chronic Pain Assessment Scales

Neonatal Facial Coding System

The Neonatal Facial Coding System is a pain scale for both preterm and full term infants. It seeks to evaluate an infant’s pain by observing signs of distress or discomfort in their facial expressions. Whether an expression occurred or not is given a score of 0 to 1.

A study by Kohut and Riddel (2008) confirmed the accuracy of the pain scale. The Neonatal Facial Coding System successfully determined which expressions were related to pain in the group of infants who were distressed prior to receiving an injection from the group who were not distressed prior to the injection.

CRIES

The CRIES pain scale stands for Crying, Requires O2, Increased vital signs, Expression, and Sleepless. It is a pain scale designed for neonates specifically. Each area of assessment is assigned a number from 0 to 2. A score of 4 or greater suggests the neonate needs medication.

Non-Communicating Children’s Pain Checklist

Some children are unable to speak due to mechanical ventilation or intellectual disabilities. The Non-communicating Children’s Pain Checklist helps assess pain in patients aged 3 to 18. It relies heavily on behavior. While it is most frequency used for non-verbal children, it can apply to non-disabled children.

Observations of the child are recorded with a number system. The advised observation time is two hours. Medical professionals or caregivers rate the frequency of behaviors using a 0 to 3 point system. “0” means the behavior was not present, “1” is rarely seen, “2” indicates the behavior was seen or heard multiple times, and “3” is when the behavior was seen or heard “often.” A score of 7 or more indicates the child is in pain.

Oxford Medicine has provided an outline for the checklist:

  • Vocal—(1) Moaning, whining, whimpering (fairly soft); (2) Crying (moderately loud); (3) Screaming/yelling (very loud); (4) A specific sound or word for pain
  • Social—(5) Not cooperating, cranky, irritable, unhappy; (6) Less interaction with others, withdrawn; (7) Seeking comfort or physical closeness; (8) Being difficult to distract, not able to satisfy or pacify
  • Facial—(9) A furrowed brow; (10) A change in eyes, squinching, wide, frowning; (11) Turning down of mouth, not smiling; (12) Lips puckering up, tight, pouting, or quivering; (13) Clenching or grinding of teeth, chewing or thrusting tongue out
  • Activity—(14) Not moving, less active, quiet; (15) Jumping around, agitated, fidgety
  • Body and limbs—(16) Floppy; (17) Stiff, spastic, rigid, tense; (18) Gesturing to or touching part of the body that hurts; (19) Protecting, favoring, or guarding a part of the body that hurts; (20) Flinching or moving the body part away, being sensitive to touch; (21) Moving the body in a specific way to show pain
  • Physiological—(22) Shivering; (23) Change in color, pallor; (24) Sweating, perspiring; (25) Tears; (26) Sharp intake of breath, gasping; (27) Breath holding
  • Eating/Sleeping—(28) Eating less, not interested in food; (29) Increase in sleep; (30) Decrease in sleep

Which Chronic Pain Assessment Scale is the Most Accurate?

Some argue that chronic pain assessment scales are unreliable. The Wong-Baker Pain Scale and Numerical Pain Scale are the most frequently used in medical facilities. However, there is not necessarily one scale that is more accurate than another. Chronic pain is complex, so the assessment of pain will be too. The chronic pain scale used depends on the situation, diagnosis, and age of the patient.

Before deciding which chronic pain scale is best, consider the following questions:

  • Is this chronic or acute pain?
  • How old is the patient?
  • Are they cognitively coherent?
  • Are they non0verbal? Can they speak?
  • Are they currently diagnosed with a medical condition?
  • Is this intended to monitor long-term treatment?
  • Are there psychological disorders present?

References

Dansie, E. J., & Turk, D. C. (2013). Assessment of patients with chronic pain. British journal of anaesthesia111(1), 19–25. https://doi.org/10.1093/bja/aet124

Kohnut, S.A., & Riddell, R.P. (2008). Does the Neonatal Facial Coding System Differentiate Between Infants Experiencing Pain-Related and Non Pain-Related Distress. The Journal of Pain, 10(2). DOI:https://doi.org/10.1016/j.jpain.2008.08.010

Mary Pat Aust; Pain Assessment in Nonverbal Patients. Am J Crit Care 1 May 2013; 22 (3): 256. doi: https://doi.org/10.4037/ajcc2013701