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Assessment of pain

Created: 6/8/2005
Updated: 31/7/2009

Assessment of pain in adults

In the assessment of pain intensity, rating scale techniques are often used. The most commonly used forms are:

 The Category Rating Scales
(e.g. none, mild, moderate, severe, unbearable or 1-5)

 The Visual Analogue Scales (VAS)
(e.g. 10 cm line with anchor points at each end). The VAS has been shown to be more sensitive to change and is therefore more widely used. These scales may also be incorporated into pain diaries.

 McGill Pain Questionnaire (MPQ) (Melzack, 1975) (78 pain adjectives arranged into 20 groups further arranged into sets of words describing sensory aspects of the quality of pain). Very widely used questionnaire.

The McGill Pain Questionnaire

The McGill Pain Questionnaire consists primarily of three major classes of word descriptors - sensory, affective and evaluative - that are used by patients to specify subjective pain experience. It also contains an intensity scale and other items to determine the properties of pain experience. The questionnaire was designed to provide quantitative measures of clinical pain that can be treated statistically. This paper describes the procedures for administration of the questionnaire and the various measures that can be derived from it. The three major measures are: (1) the pain rating index, based on two types of numerical values that can be assigned to each word descriptor; (2) the number of words chosen; and (3) the present pain intensity based on a 1-5 intensity scale. Correlation coefficients among these measures, based on data obtained with 297 patients suffering several kinds of pain, are presented. In addition, an experimental study which utilised the questionnaire is analysed in order to describe the nature of the information that is obtained. The data, taken together, indicate that the McGill Pain Questionnaire provides quantitative information that can be treated statistically, and is sufficiently sensitive to detect differences among different methods to relieve pain.


Melzack R.
The McGill Pain Questionnaire: major properties and scoring methods.
Pain 1975; 1:277-99

Click here to view short form of MPQ.

 The Illness Behaviour Questionnaire (Pilowsky, Spence 1975) was also developed, to help describe the constituents of abnormal illness behaviour. The major dimensions derived from factors analysis are: phobic concern about one’s health, conviction of disease, perception of somatic versus psychological illness, affective inhibition, affective disturbance, denial of other problems and irritability.

 Minnesota multiphasic personality inventory is also used for pain assessment.

Assessment of pain in children

In children, pain can be measured by self-report, biological markers and behaviour. Because pain is a subjective event, self-report is best if it is available. Unfortunately, in many infants, young children, or children with cognitive or physical impairments, self-report is not available and behavioural or biological measures must be used.


Children as young as 2 years of age can report pain, although at this age they are not able to rate intensity. Children at any age may deny pain if the questioner is a stranger, if they believe they are supposed to be brave, if they are fearful or if they anticipate receiving an injection for pain.

Children of 4 or 5 years of age can use standardised measures. Hester’s Poker Chip Tool is well validated and works effectively in this age group because it is concrete. Four poker chips are placed in front of the child and the chips are described as pieces of hurt. The first chip is described as "just a little hurt", the second is "a little more hurt", the third chip is "more hurt" and the fourth chip is "the most hurt you could have". The child is asked, "How many pieces of hurt do you have?". The response is then confirmed.

Face scales can often be used in this age group. Children are asked to indicate their pain by pointing to one of the faces. Usually the child is trained by asking how he or she would feel following some minor pain and then a more severe pain.

Wong-Baker FACES Pain Rating Scale

Children of 6 or 7 years of age can use word-graphic rating scales. Children are asked to indicate how much pain they have on a line with five verbal anchors. At this age, children can use 0-10 or 0-100 scales, with 0 being "no pain" and 10 or 100 being "the worst possible pain". Similarly, a 10 cm line with anchors of "no pain" and "the worst possible pain" (a visual analogue scale) can be used. The data do not suggest that any one scale of this type is better than another.

Wong DL et al (eds). Nursing Care of Infants and Children, 6th edition. St Louis, Mosby-Year Book, 1999.

Biological measures

Heart rate initially decreases and then increases in response to short, sharp pain. Vagal tone and heart rate variability, such as during breathing, have been used as indices of pain and distress. No studies have evaluated heart rate as a measure for longer-term pain, although heart rate is not substantially elevated during postoperative pain in older children. Ill and premature babies have less predictable responses. Heart rate is an easy and generally valid measure of short, sharp pain. Unfortunately, there appear to be no biological measures that can be recommended for use as a clinical pain measure for longer-term pain.

Oxygen saturation decreases during painful procedures such as circumcision, lumbar punctures and intubation, but can occur for other reasons or just during handling of neonates. Children may have normal oxygen saturation despite significant pain over a long period.

Surgery or trauma triggers the release of stress hormones. This cascade may facilitate healing but can have disastrous results in the sick neonate. The stress response is blunted by opioids, probably by several actions at the hypothalamic and pituitary level. The stress response is more than a measure of pain.

Cortisol release, widely studied in infants and children, is not specific to pain and occurs in many adverse situations. Plasma cortisol levels rise significantly during circumcision. However, sick premature babies may have unstable levels, and small changes during painful procedures may not be detectable. Cortisol changes with routine inoculation in healthy infants, but the response depends on a complex interaction of age, behaviour and baseline values. This complexity precludes cortisol as a clinical pain measure, even for short sharp pain.

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