What is the Widespread Pain Index and how is it used?

The WPI was introduced in 2010 by the American College of Rheumatology as part of new diagnostic criteria for fibromyalgia. It enables a standardised assessment of the spread of pain in the body.

The Widespread Pain Index is based on a standardised questionnaire. In this questionnaire, patients indicate in which region of the body they have experienced pain in the past seven days. This information is binary, i.e. each body region is rated as 1 = pain or 0 = no pain.

In total, the WPI measures pain in 19 defined body regions or pain zones.

On the front of the body, the pain zones are

• Jaw,
• Neck,
• Chest (thorax),
• Abdomen.

On the back of the body they are

• Upper back,
• Lower back,
• Hips & buttocks.

On the shoulders Shoulders and extremities the pain zones are

• Shoulder or shoulder girdle
• Upper arm
• Lower arm
• Thigh
• Lower leg & foot

One point is awarded for each painful region. Accordingly, the total score can range from 0 to a maximum of 19 points.

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What does the Widespead Pain Index say?

The Widespread Pain Index records the spread of pain in the body. It indicates in which regions of the body pain has occurred. In doing so, it disregards the intensity and type of pain experienced.

Viewed on its own, the WPI therefore indicates how widespread pain is in the body.

When used regularly, the WPI also allows continuous measurement of the spread of pain. It shows whether pain has occurred in the same areas of the body or whether the spread of pain is changing.

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Benefits of the Widespread Pain Index

The WPI is an important tool in modern fibromyalgia diagnostics, which enables standardised recording of the spread of pain.

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Focus on the spread of pain

The WPI focuses specifically on the spread of pain in the body, not its intensity. It measures how many of 19 defined body regions pain occurs in. Unlike previous dichotomous definitions of ‘widespread pain’, the WPI provides a continuous measure of pain spread on a scale from 0 to 19.

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Subjective measure

The WPI is based entirely on patient-reported data. It does not require any additional medical examination of e.g. pain points. This distinguishes it from older methods such as the counting of pressure pain points (tender points or trigger points). The examination of trigger points can be associated with further pain for patients, as the treating doctor has to apply pressure to the defined points in order to assess the pain.

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Easy to use

The WPI is comparatively easy to use. Patients simply indicate in which parts of the body they have experienced pain in the last seven days. A physical examination is not necessary.

The defined body regions can also help patients to scan their body. For such a ‘scan’, one directs one's thoughts through the body in a structured way and can thus localise pain.

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Specific to fibromyalgia

The WPI was developed specifically for the diagnosis of fibromyalgia and is part of the official diagnostic criteria of the American College of Rheumatology. The WPI is used in combination with the Symptom Severity Scale (SSS) to provide a more comprehensive assessment.