How do we Measure Pain?


Whether pain is acute or chronic, injury or disease-related, located in the back or the head or somewhere else in the body, doctors will often ask their patients to quantify their pain using a pain rating scale.

This can be difficult for patients, and the fact that pain is complex, subjective and affected by numerous individual factors, such as mood and thought patterns, may make this seem like a pointless idea to some, but the use of these tools is an invaluable and important component of effective pain management.

Pain assessment tools allow doctors to assess the effectiveness of a treatment in a patient, be it pharmaceutical, a device or physical or psychological therapy. Of course, effective pain management is most often achieved with combination therapy and/or a multidisciplinary approach, in which case numerous assessment tools may be used in order to track the patient’s progress. Pain assessment tools are also fundamental to clinical trials, in which a new drug or treatment is trialled in a population of patients with a very specific type of pain (i.e. osteoarthritis of the knee, post-herpetic neuralgia or complex regional pain syndrome).

There are a many different pain assessment tools. Some of the most commonly used pain rating scales are described below:

Visual Analogue Scale (VAS)

Pain scale2

This is a very simple but effective tool. It consists of a 100mm line, usually with numerical or descriptive labels at each end, such as that pictured above. The patient simply has to put a mark on the line at the point where they feel their level of pain exists. A clinician or researcher quantifies this by measuring the distance from the mark to the start of the line with a ruler, therefore scoring the pain out of 100. This scale is commonly used in clinical trials because it is well-validated and more sensitive than other scales.

Numerical Rating Scale (NRS)

This is an 11-point scale in which the patient is asked to rate their pain on a scale of 0 to 10, where 0 = no pain and 10 = the worst pain imaginable. This tool is quick and simple for clinicians as it can be administered verbally (i.e. in consultation or via telephone) and has also been validated.

Verbal Rating Scale (VRS)

This scale consists of a ranked list of pain intensity descriptors. For example: 0 = no pain, 1 = mild pain, 2 = moderate pain, 3 = severe pain, 4 = very severe pain, 5 = worst pain. Though it seems simple, some patients have difficulty with this scale if they feel that their pain cannot be described by any of the list items or fits somewhere in-between descriptors.

Face Pain Scales

Pain scale

Pain rating scales using pictures of emotive faces corresponding to varying pain intensities are particularly useful when dealing with children or illiterate patients. The scale must be explained to the patient in a way that minimises associating the faces with emotion (i.e. happy or sad). Two popular examples are the Wong-Baker FACES® Pain Rating Scale and the Faces Pain Scale – Revisited.

Brief Pain Inventory (BPI)

This is a questionnaire that assesses multiple dimensions of a patient’s pain. The short-form is most commonly used - it consists of 9 sections and should only take 5 minutes to complete. The BPI includes a body diagram for the patient to illustrate the distribution of their pain, numerical pain rating scales, a section to list current treatments and the level of relief that they are providing, and a series of numerical rating scales to describe how pain is interfering with various aspects of the patient’s life.

Other Pain Assessment Tools

Because pain is such a complex symptom, varies depending on the underlying diagnosis or disease, and is often associated with other symptoms, these simple pain assessment tools are often used in combination with other assessment tools. Some examples include:

  • Disability questionnaires: i.e. the Oswestry Disability Index (ODI) and the Roland Morris Disability Questionnaire (RM).
  • Psychometric questionnaires: i.e. the Depression Anxiety Stress Scale (DASS), the Tampa Scale for Kinesiophobia (TSK) and the Pain Catastrophizing Scale (PCS).
  • Lifestyle assessment tools: i.e. the Quality of Life Scale (QOLS) and the Pain Self Efficacy Questionnaire (PSEQ).

References & Further Reading

  1. Pain Management Network. Assessment.
  2. PainFocus. Pain assessment scales.
  3. Pain Community Centre. Pain Assessment Tools.
  4. International Association for the Study of Pain. Faces Pain Scale – Revised. 2001.
  5. MD Anderson Cancer Center. The Brief Pain Inventory (BPI).
  6. Pain Australia. Clinical Assessment of Pain (Fact Sheet 3).
  7. Williamson A and Hoggart B. Pain: a review of three commonly used pain rating scales. Journal of Clinical Nursing. 2005;14:798-804.
  8. Image by Robert Weis (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons

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