MEASUREMENTS OF CHRONIC PAIN AND FUNCTION
Chronic pain can be defined as pain that is present on a daily or almost daily basis for three months or more. Once pain has been present for this length of time, it is difficult to eradicate and some continuing pain will often have to be accepted by the patient.
Accurate figures on the incidence of chronic pain are not available. However, data from various surveys suggest, that in 1989, at least one-third of the American population suffered from some sort of chronic pain.
When assessing patients in chronic pain and their response to treatment the primary physician can document various aspects that can assist in both diagnosis and response to therapy.
Spatial Distribution of Pain: Getting the patient to mark, or shade in, painful areas on a line drawing of the body can indicate possible anatomical causes. Shading of the whole extremity, or several body areas, makes identification of a single physical pain source less likely. In these cases, psychological and environmental issues should be explored.
The Visual or Verbal Analogue Pain Score (VAS): The patient is asked to score their pain from 0 to 10, where 0 is no pain and 10 is the worse pain possible. Having a score allows treatment to be assessed. If the individual persistently complains of pain 10/10 "or higher" significant, real or perceived, environmental stresses are often present. "Smiling faces" may be used in younger patients.
Pressure Algometers: Some forms of chronic pain have myofascial triggers and tender points. A spring-loaded algometer placed on these areas allows the pressure that causes pain to be documented. This is moderately reliable in measuring pain thresholds and can be used for to fulfill diagnostic criteria in primary fibromyalgia as well as to follow the effects of therapy.
Disability: This can be measured by a number of different methods. The Sickness Inventory Profile (SIP) is reliable and valid. It provides useful clinical information in physical function, communication, cognitive and social activity.
A simpler graded classification of pain and disability has been proposed (Von Korff et al 1992). Here the level of disability due to pain is divided into low, where the pain does not interfere with usual activities or high where the pain significantly interferes.
These gradings are:
- Low disability low intensity pain
- Low disability high intensity pain
- High disability moderately limiting
- High disability severely limiting.
In 3 and 4 grades pain is rarely less than 5 /1 0 on a scale where 0 is no pain and 10 is the worse pain possible.
Verbal Pain Descriptors: These ca be measured using the McGill Pain Questionnaire (MPQ). This is a patient checklist of 20 groups of adjectives the patient fills in according to how they perceive their pain. Descriptors such as wretched or sickening often indicate a large affective component to the pain
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