How is pain measured?

Pain is an unpleasant sensory and emotional experience and is, therefore, always associated with an emotion. Additionally, this pain may be due to actual or potential damage. Pain is, therefore, a subjective concept and exists whenever a patient says that something hurts.

It is a very prevalent pathology in the general population and has a great socioeconomic impact, as it is very disabling. Any pain lasting more than 3 months is considered chronic pain.

So how can we measure pain? Dr Christian Dürsteler, head of the Clinical Pain Section at the Hospital Clínic Barcelona, explains that this is a very complex matter. “We are talking about something that is partly emotional, and we know that emotions are very difficult to measure. Blood sugar or cholesterol can be measured, but, when talking about emotions, how can emotions such as fear, envy or anger be measured? It is very difficult," highlights the doctor.

In addition, it must be taken into account that pain awakens other emotions such as stress or anxiety. These in turn negatively impact and accentuate the pain.

Currently, scales and questionnaires are used to assess pain; for example, a numerical scale from 0 to 10 or a visual scale. These are the scales used most to measure pain:

• Visual analogue scale: This consists of a 10 cm horizontal line. One end represents the minimum and the other the maximum pain intensity. Patients are asked to mark the point on the line that best relates to the pain intensity they feel. This point is measured with a ruler and the pain intensity expressed in centimetres.
• Numerical scale: This ranges from 0 to 10; with 0 representing no pain and 10 pain of the greatest intensity. It is the simplest and most used scale.
• Categorical scale: This expresses the intensity of the symptom in categories such as “not at all”, “a little”, “quite a bit” and “a lot”. An association is then established between these categories and the numbers 1 to 10.

(Image of scales; Source: Valencia University)

These scales, and other questionnaires and measuring ranges are useful, but not very specific for measuring pain levels. In fact, studies comparing the different methods indicate that the methods used most to measure pain are all valid, but none are conclusive. So, it is down to health professionals and researchers themselves to decide the method used, depending on the patient and type of pain in each case.

For all these reasons, the conclusion is that “it is really very difficult to measure something that is associated with emotions. It is one of the obstacles that we as health professionals have,” concludes Dr Dürsteller.