C) Psychology and Health – Pain

i) Types and theories of pain

What is pain?

See class exercise

There are various ways in which types of pain have been categorised:

Acute –

Chronic –

Rigge (1990) -

Organic –

Psychogenic –

Definition by Merskey (1986) -

What is the purpose of pain?

Injury without pain

Congenital analgesia –

Case study – Miss C.

Episodic analgesia –

Beecher (1959) –

Carlen (1979) -

Melzack and Wall suggests six characteristics:

Pain without injury

Neuralgia -

Causalgia –

Fibromyalgia - The occurrence of body-wide pain in the absence of tissue damage, as in fibromyalgia, interferes with all aspects of a person's life and undermines their credibility. The problem is that normal activities can be exhausting, sleep is disturbed, the ability to concentrate is impaired, gastrointestinal function is often abnormal, persistent headaches are common, and the unrelenting pain that no one can see is often detrimental to their personal and professional lives--as it creates a "credibility gap."

Case-study, Headaches.

Case – study Phantom limb pain (Melzack 1992)

Introduction –

List the seven features identified by Melzack (92)

What explanations of phantom limbs have been given (include Melzack’s model)

How can it be treated?

Theories of Pain

1 Specificity theory,

Von Frey (1895)

Melzack and Wall (1988)

Chery Croze and Duclaux (1980)

2 Sensory Decision Theory

This theory relies heavily on the psychological perception of a painful stimulus.Painful stimuli is perceived according to the individuals cognitive processes eg* perceptual habits* beliefs* expectations * costs and rewards* memory of previous pain experiencesTherefore this theory espouses that individual characteristics and situational factors affect pain. It allows for the need to focus on the painful area in order to become aware of the pain signals eg footballer.

3 Pattern theories -

4 Gate control theory (Melzack and Wall, 1965)Gate Control model (Melzack and Wall, 1965)

Evidence on the Gate-Control Theory

Reynolds (1969) found that rats electrically stimulated in the periaqueductal gray area were able to tolerate pain (a clamp applied to their tails). Morphine works by acting directly on the periaqueductal gray area. It is thought this area works by sending signals down from the brain in order to close the gate.

Stimulation to the brainstem is known as stimulation-produced analgesia (SPA). Pain fibres produce substance P, in order for the pain signal to cross the nerve synapse. SPA causes another chemical to block substance P.

The body produces endogenous opioids that act as a natural analgesic. Endogenous opioids can be tested by using naloxone. This drug can counteract the analgesia produced by the endogenous opioids. It is thought the endogenous opioids can be produced by electrical stimulation-produced analgesia (SPA). Naloxone blocks the analgesic effect of SPA so it is thought that endogenous opioids are produced by SPA (Akil et al 1976). Injecting Naloxone into patients after dental treatment increases their pain (Levine et al 1978). Naloxone does not always block SPA, it depends upon where the electrical stimulation is applied within the periaqueductal grey area.

Melzack and Wall conclude:

1. There are several descending control systems, some are sensitive to naloxone, but others are not.

2. Many other non-opioid transmitters, such as noradrenalin, acetylcholine and dopamine are also involved in analgesia.

The effect of endogenous opioids on pain may be dependent upon how long the pain lasts. Morphine taken to relieve short episodes of pain, tolerance develops quickly. When morphine is given to patients suffering from long-term pain (e.g. cancer) they do not develop tolerance (Melzack and Wall, 1982).

In times of stress, for example in sport or on the battlefield, endogenous opioids are released (Bloom et al 1985). This will explain why soldiers can fight on with little pain, even though they are severely injured.

Sarafino (1994), ‘the pain gate’

Culture and pain

Melzack (1973) presents evidence of the way in which culture can affect the experience of pain. In some remote Indian villages, an annual hook swinging ceremony takes place. Two steel hooks are placed into the lower back of a youth who is to experience the ceremony. He is then hoisted on to a pole and transported from village to village. During the whole of this process the youth displays no pain whatsoever, despite what must appear to be excruciating pain. Of course, we are unable to measure the degree of pain experienced and can only infer from the youth’s reaction that little pain was present. However, there are observable cultural differences in response to pain.

Zborowski (1969) reports that behavioural expressions of pain differ among ethnic groups of patients in medical settings. The differences were thought to be due to the attitudes and values of the ethnic groups. Third-generation Americans tended to respond to the pain in a matter of fact way, and acted as if they should be ‘good, uncomplaining patients’. The Irish were similar in their pain expressions, but their suffering was communicated to observers. On the other hand, more overt responses to the pain were forthcoming from Italian and Jewish sub-cultures. The Italians felt that pain had to be avoided at all costs, and their expressions were aimed at the elimination of the pain. The Jewish group were more concerned with the memory of pain and its implications.

The idea that culture in its broadest terms affects the expression of pain and the view that health professionals should be aware of these differences is laudable, but care must be taken to avoid falling into the trap of stereotyping patients’ pain responses on the basis of their cultural origin.

Davitz & Davitz (1985) said that if nurses are asked directly about the question of cultural stereotypes and pain, they resent any implication that they operate on the basis of cultural stereotypes. To find out whether nurses are influenced by stereotypes they presented American nurses with a brief vignette describing an adult patient.

Sample vignette Name of patient: Michael O’HaraAge:37Background: Irish Michael O’Hara, struck by an automobile, was admitted to the hospital with a fractured femur and facial injuries. Currently in traction, he is to remain hospitalised for an indefinite period. The experimenters first of all varied the cultural background of the person, so that each patient had the same physical condition, age and sex but a different ethnic background. The six ethnic background variables were: Oriental, Mediterranean, Black, Spanish, Anglo-Saxon, Germanic and Jewish. They also investigated varying the severity of the illness (mild, moderate and severe). The mean ratings of physical pain and psychological distress for each group of patients and for each level of severity of illness were measured.For both physical pain and psychological distress, nurses believed that Jewish and Spanish patients suffered most, while Oriental and Anglo-Saxon/Germanic patients suffered the least. Jewish patients were perceived as suffering relatively greater pain and psychological distress in cases of psychiatric and cardiovascular illnesses.Davitz & Davitz (1985) say:The results of this research clearly indicate that one aspect of American nurses’ belief systems about suffering involves the ethnic or religious backgrounds of their patients. In discussing our research with nurses, we have found that some nurses react defensively to our findings. They strenuously insist that they never generalise, that they treat all patients as individuals.

That may indeed be the case for particular nurses, but our data do indicate that in general, American nurses in fact tend to share certain generalised beliefs about patients. To summarise, whilst one cannot objectively measure the experience of pain, the fact that people in excruciating circumstances do not seem to be in pain due to the social nature of the event suggests that culture may indeed affect the pain experience. Secondly, there does seem to be consistent evidence that people from different cultures and subcultures respond to pain in overtly different ways. Thirdly, health professionals hold stereotypical views of pain.

2 Controlling Pain

There are various techniques for controlling pain

Pain relieving chemicals/Medication Behavioural and cognitive methods for treating pain Hypnosis Inside oriented psychotherapy Physical and stimulation therapies for pain

Medical Approach - Pain relieving chemicals

Chemical - Aspirin -Acetylsalicylic acid - found in Willow trees, as discovered by a clergyman from Chipping Norton in 1763 - it relieved his rheumatism and bouts of fever.

Aspirin, Ibuprofen, Paracetamol (acetaminophen)Against painAgainst inflammationAgainst feverOpium used before then, as early as 1550 BC

From Opium is produced morphine, heroin and codeine - all produce analgesia, drowsiness, change of mood, mental clouding.

Inhibit pain messages (close the gate).Opiates work well because many nerves respond to opiates.

Peripherally active analgesics, for example aspirin which acts on the peripheral nervous system by inhibiting the synthesis of neurochemicals

Centrally acting analgesics, for example narcotics derived from the opium poppy, which acts on the central nervous system. There is a problem of tolerance and addiction though.

Local anaesthetics. These act directly on the site whether pain originates. The problem is that the drugs will paralyse muscles in the region as well.

Indirectly acting drugs. These drugs include sedatives, tranquillisers, antidepressants, and anticonvulsants. Sedatives, such as barbiturates and tranquillisers such as diazepam are depressants that depress bodily functions.

The problem is the patient could become psychologically and physically dependent upon the drugs. Antidepressants, such as doxepin, helped patients by reducing the psychological depression that accompanies chronic pain. Anticonvulsants inhibit random nerve impulses, which will control some types of pain.

Severe Phantom limb pain was treated, over a two-year period, with methadone and antidepressants. The patients who had had the pain syndrome for an average of five years reported that their pain had been reduced by about two thirds. This was maintained over the following two years using very low daily doses of each drug (Urban et al., 1986). The good news here is that the patients did not become addicted to the drugs.

Patients suffering from headaches under the double blind procedures given painkillers and placebos sometimes reported that the placebo relieved their headache (Andrasik, Blake, and McCarran, 1986). This would suggest that other psychological techniques might be equally as effective.

Some patients may not like being referred to a psychologist. They may not see the relevance, or they may think the doctor does not believe the pain is real, or the patient may believe the doctor considers them psychologically maladjusted. To overcome this problem the doctor should make it clear that they believed the patient is in a great deal of pain, that working with other professionals would be a good idea and that the doctor would be an active part of the team.

Bush et al (1989) -

Patients in hospital tend to demand medication too often, which inconveniences the busy staff. Allowing the patient to self-administer their medication has led to the unexpected result that they receive less of the drug than others who receive injections on demand. It would seem that once the patient feels in control they can manage without the drug for longer. Naturally the machine that allows the patients to self inject does restrict the amount and rate of injections in order to avoid an overdose, but this would not explain why self administering patients manage on less pain killer than other patients, who would be subject to a controlled dose as well.

Behavioural and cognitive methods for treating pain

Operant - useful if patient has developed inappropriate response to the pain (e.g. too many tablets).

Use social reinforcement to gradually increase activity levels Gradually decrease the use of medication Training carers not to reinforce pain behaviours by being sympathetic

The operant approach

An example of the operant approach for a child with burns.The child cries and complains of pain when ever she puts on her splints. The hospital staff has been giving attention to the crying behaviour. The remedy is as follows:

Ignore the pain behaviours Provide rewards for compliant behaviour Give praise if the child helps in putting on the splints etc..

A technique for reducing medication is as follows:

Use a fixed schedule, such as every four hours, rather than when ever the patient requests it. The drug therefore does not become a reward for the patient. In addition, the medication is mixed with flavoured syrup to mask its taste. Over a period of several weeks the dosage is gradually reduced, but the patient because of the syrup does not detect this.

Fordyce (1973) –

Bonica and Fordyce (1974) -

Problems with these studies

Studies often do not include control groups, so it is difficult to know whether the operant methods changed the behaviour or some other factor, such as being studied.

The technique is not suitable for chronic progressive pain, such as in cancer patients.

Patients who are unwilling to participate or who receive disability compensation are not likely to benefit from this technique.

 Relaxation and biofeedback

Patients using the technique of progressive muscle relaxation focus their attention on specific muscle groups while alternately tightening and relaxing these muscles. Patients who received training in relaxation to control pain are urged to use this technique to reduce feelings of stress, particularly if they feel pain episodes coming on.

In biofeedback procedures, patients learned to exert voluntary control over a bodily function, such as heart rate, by monitoring its status with information, usually from

electronic devices. Muscle contraction headaches can be treated by biofeedback procedures. Patients learned to control the tension of specific muscle groups -such as those in the scalp and neck- by receiving biofeedback from an electro-myograph (EMG.) device. Another method used for migraine headaches, focuses on the constriction and dilation of arteries -such as those in the head- which can be measured indirectly on the basis of the temperature of the skin in the region of the target blood vessels. Biofeedback techniques, such as these, can be used at home whenever a patient feels a pain episode is about to begin.

Biofeedback techniques have been shown to be successful in controlling headaches, but there has been little evidence of biofeedback procedures being effective in relieving other types of pain. Treatment with relaxation and biofeedback is about twice as effective in relieving pain as placebo conditions. A combination of relaxation and biofeedback has been shown to be more successful than biofeedback on its own. Biofeedback has been shown to be more successful than relaxation techniques. (Holroyd & Penzien, 1985). There is much variability in the success of these techniques. Middle-aged and elderly patients seem to gain relatively little relief with these treatments (Blanchard & Andrasik, 1985). Biofeedback treatment is relatively expensive to conduct, and the likelihood of improvement beyond just using relaxation for many pain conditions may not justify its expense (Turk, Meichenbaum & Berman, 1979). There is some evidence that most children and people who show certain psychophysiological patterns, such as a high correlation between their pain and EMG. Levels, may be better candidates for biofeedback treatment than other people (Attanasio et al., 1985).

Other Cognitive techniques

Researchers asked children and adolescents what they think about when getting an injection at their dentists (Brown, O'Keeffe, Sanders, & Baker, 1986). Over 80% of these subjects reported thoughts that focused on negative emotions and pain, such as, "this hurts, I hate injections," "I'm scared," and "my heart is pounding and I feel shaky." One fourth of the subjects had thoughts of escaping or avoiding the situation, as in, "I want to run away." These types of thoughts focus the persons attention on the unpleasant aspects of the experience and make the pain worse (Turk, Meichenbaum, & Genest, 1983). Many people use cognitive strategies to modify their experience of pain. For instance, by 10 years of age, many children reports that they tried to cope with pain in a dental situation by thinking about something else or by saying to themselves such things as, "it's not so bad," or, "be brave" (Brown, O'Keeffe, Sanders, & Baker, 1986).

People cope with chronic pain by using one of two strategies:

1. Active coping, in which they try to keep functioning by ignoring the pain or keeping busy with an interesting activity.

2. Passive coping, such as taking to bed or curtailing social activities.

The problem with passive coping is that this leads to feelings of helplessness and depression, which leads to more passive coping, and so on (Smith & Wallston, 1992). Patients who feel that their pain will last a very long time and their doctors don't know what causes their pain tend to cope poorly. On the other hand, patients who believe

that they understand the nature of their pain and that their conditions will improve tend to use active coping strategies.

Kontantji et al (2000) has demonstrated the different ways in which high-pain frequency students compared with low-pain frequency students process sensory or affective words that are associated with pain. The high-pain students, being those who experienced pain quite often, recalled more sensory and affective words when they were incidentally learnt by self-referencing them (thought of in relation to themselves) compared to when they were other referenced (thought of in relation to a friend). Affective words included: unbearable, discomforting, mild, horrible, fearful, and cruel. Sensory words included: scolding, stabbing, pressing, boring, pounding, tugging, tender. This demonstrates how cognitive processes are affected by pain.

Coping techniques can be classified into three basic types:

1. Distraction, 2. Imagery, 3. Redefinition (Fernandez, 1986).

Basler and Refisch (1990) –

Distraction

Distraction is the technique of focusing on a non-painful stimulus in the immediate environment in order to divert our attention from discomfort. Research has shown that distraction is more effective if the pain is mild or moderate than if it is strong (McCaul & Malott, 1984).

A laboratory experiment involving college students rated the subjects pain distress for holding their hand in cold water. Subjects given a distraction task involving numbers did not give lower pain ratings than controls, who just watched numbers being displayed (McCaul, Monson, & Maki, 1992). This result might be because subjects needed to believe that these distraction techniques would relieve pain. Subjects believing that loud sound would relieve pain, listened to the sound and did not feel as much pain (using the cold-presser procedure, hand in cold water) as did controls who were listening for a non-existent hum (Melzack, Weisz, & Sprague, 1963).

Its importance that patients understand that distraction can work. One therapist used the analogy of a TV set. For example whilst watching channel 11, channel nine is still being received. The metaphor means whilst the patient is attending to a non-painful stimulus the pain is still there but is not tuned in.

Distraction works best for acute pain, such as the pain experienced in a dental surgery. Chronic sufferers might find it useful to engage in an extended activity, such as watching a film or reading a book.

Imagery

Non-pain imagery-sometimes called guided imagery-is a strategy whereby the person tries to alleviate discomfort by conjuring up a mental scene that is unrelated to or incompatible with the pain (Fernandez, 1986). Therapists encourage the patient to include aspects of a variety of senses: vision, hearing, taste, smell, and touch. Imagery is like distraction except that imagery is based on the person's imagination rather than on real objects. The advantage here is that the patients can develop one or more scenes that work reliably and carry them around in their heads. Imagery works best for people with mild or moderate pain than with strong pain. A disadvantage is that some patients are less adept in imagining scenes than others.

Redefinition

Pain redefinition is when the person substitutes constructive or realistic thoughts about the pain experience for ones that arouse feelings of threat or harm. Therapists can help by providing information about the sensations to expect in medical procedures. There are basically two kinds of self-statements for controlling pain:

Coping statements emphasise the person's ability to tolerate the pain by saying to themselves, "it hurts, but you're in control," or, "be brave-you can take it."

Reinterpretative statements are designed to negate unpleasant aspects of the pain, as when people think, "it is not so bad," "it's not the worst thing that could happen," or, "it hurts, but think of the benefits of this experience."

Evaluation of cognitive strategies in controlling pain

Cognitive strategies are effective in reducing acute pain. Distraction and imagery seem to be particularly useful with mild or moderate pain, and redefinition appears to be more effective with strong pain. A combination of behavioural and cognitive methods is at least as effective as chemical methods in reducing chronic muscle-contraction headaches (Holroyd et al., 1991). Patients with a variety of medical problems including arthritis, amputation, and spinal cord injury reported that redefinition helped in reducing the experience of pain more than distraction did (Rybstein-Blinchik, 1979). Arthritis sufferers received a five-week pain control programme that included training in distraction, imagery, and redefinition. The programme gave special emphasis to having the patients use these techniques in specific painful activities, such as carrying groceries, climbing stairs, and mopping floors. A control group simply received a self-help book for arthritis sufferers. The

control group showed little improvement but the treated group reported having less pain, greater self-efficacy, less depression, and improved Sleep patterns.

A programme combined imagery, redefinition, and progressive muscle relaxation training to treat chronic low back pain patients. This programme was compared with one that consisted of only relaxation training, and a control group. Patients in the two treatment programmes reported much less pain, depression, and disability. The patients were benefiting from these two programmes more than a year and a half later. The patients who had been trained in cognitive strategies and relaxation showed an improvement in their employment, working 60 per cent more hours per week than those who had the programme of relaxation only.

Hypnosis

Insight-oriented psychotherapies for pain

This technique involves chronic pain patients gaining insights into the way that the pain is affecting their behaviour and the way their interpersonal relationships are being affected. Pain behaviour is seen as part of "pain games" they play with other people (Szasz, cited in Bakal, 1979). In these games, the patient takes on a role in which they continually seek to confirm their identity as suffering persons, maintain their dependent lifestyles, and receive various rewards, such as attention and sympathy. The patients are most likely unaware of the game they are playing; it is the purpose of this psychotherapeutic approach to make them aware.

Surgical attempts

Cutting nerve pathways - gives temporary relief. Only recommended for people who are terminally ill.

Physical therapies

Manual therapies e.g. massageMechanical therapies e.g. tractionHeat treatments e.g. microwave diathermy, ultrasound.Cold treatments e.g. ice packsElectrotherapy - electrical nerve stimulation..

Self-efficacy (see booklet (b))

3 Measuring Pain

Karoly (1985) – six key elements

Techniques used to collect data:

Physiological measures of pain (use of EMG and EEG)

Evaluation (advantages and disadvantages)

Observations of pain behaviours

People tend to behave in certain ways when they are in pain; observing such behaviour could provide a means of assessing pain.

Turk, Wack and Kerns (1985) –

• Facial /audible expression of distress –

• Distorted ambulation or posture –

• Negative affect –

• Avoidance of activity -  

One way to assess pain behaviours is to observe them in a clinical setting (although pain is also assessed in a natural setting as the patient goes about his or her everyday activities). Keefe and Williams (1992) have identified five elements that need to be considered when preparing to assess any form of behaviour through this type of observation. • A rationale for observation

• A method for sampling pain behaviour

• Definitions of the behaviour

• Observer training

• Reliability and validity

 

A commonly used example of an observation tool for, assessing pain behaviour is the UAB Pain Behaviour Scale designed by Richards et al (1982). See Harari page 67 for copy of the scale.

Commentary

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Self-report measuresBecause pain is a subjective, internal experience, the assessment of pain is therefore best carried out by using patient self-reports, and this is by far the most frequently used technique.

Carroll (1993a) lists the different dimensions of pain that sufferers can be questioned about: • Site of pain: where is the pain?• Type of pain: what does the pain feel like?• Frequency of pain: how often does the pain occur?• Aggravating or relieving factors: what makes the pain better or worse?• Disability: how does the pain affect the patient’s everyday life?• Duration of pain: how long has the pain been present?• Response to current and previous treatments: how effective have drugs and

other treatments been? 

An important item to add to this list is the emotional and cognitive effect of the pain—in other words, how does the pain make patients feel and how does it affect their thought processes and attitudes? 

Two types of self-rating scales

1. Visual analogue

Patients mark a continuum of severity from "No Pain" to "Very Severe Pain"

Simple and Quick to use and can be filled out repeatedly

Can track the pain experience as it changes - this could reveal patterns such

as situations or times of the day when the pain is better or worse

This method has adequate reliability, however limits pain to a single dimension. Downie and colleagues evaluated the degree of agreement between various scales in patients with rheumatic diseases and found a high correlation among the different types of scales. The scales are simple to understand and do not demand a high degree of literacy or sophistication on the part of the patient, unlike other pain measurement tools, such as the semantic differential scales described below. The Visual Analogue Scale is simple and quick to administer, and may be used before, during, and following treatment to evaluate changes in the patient's perception of pain relative to treatment. The scales may also be completed throughout the course of a day to assess change in pain intensity relative to activity or time of day.

2. McGill Pain Questionnaire (MPQ)

The McGill Pain Questionnaire, developed by Melzack (1975), was the first proper self-report pain-measuring instrument and is still the most widely used today. See page 69 for copy of the questionnaire.

An attempt to find words to describe experiences of pain was made in a study by Melzack and Torgerson (1971) in which they asked doctors and university graduates to classify 102 adjectives into groups describing different aspects of pain. As a result of this exercise, they identified three major psychological dimensions of pain:

 • sensory

• affective

• evaluative Each of the three main classes was divided into a number of sub-classes (sixteen in total). For example, the affective class was sub-divided into tension (including the adjectives ‘tiring’, ‘exhausting’), autonomic (including ‘sickening’, ‘suffocating’) and fear (including ‘fearful’, ‘frightful’, ‘terrifying’).

Melzack and Torgerson (1971) then asked a sample of doctors, patients and students to rate the words in each sub-class for intensity. The first 20 questions on the McGill Pain Questionnaire consist of adjectives set out within their sub-classes, in order of intensity. Questions 1 to 10 are sensory, 11 to 15 affective, 16 is evaluative and 17 to 20 are miscellaneous.Patients are asked to tick the word in each subclass that best describes their pain. Based on this, a pain rating index (PRJ) is calculated: each sub-class is effectively a verbal rating scale and is scored accordingly (that is, 1 for the adjective describing least intensity, 2 for the next one and so on). Scores are given for the different classes (sensory, affective, evaluative and miscellaneous), and also a total score for all the sub-classes. In addition, patients are asked to indicate the location of the pain on a body chart (using the codes E for pain on the surface of the body, I for internal pain and El for both external and internal), and to indicate present pain intensity (PPJ) on a 6-point verbal rating scale. Finally, patients complete a set of three verbal rating scales describing the pattern of the pain.

Criticism of this questionnaire centres on the need to have extensive understanding of the English language eg discriminate between words such as "Smarting" and "Stinging"

Semantic differential scales, such as the McGill, are difficult and time consuming to complete and demand a sophisticated literacy level, a sufficient attention span, and a normal cognitive state. They therefore are less convenient to use in the clinical environment, but have value when a more detailed analysis of a patient's perception of pain is needed, as in a pain clinic or clinical research setting.

The issue of reliability has been addressed in numerous reports, particularly as it concerns the VAS and the McGill Pain Questionnaire. These reports do not lead to a consensus on reliability of these measurements. They suggest that reliability varies based on the patient groups that were examined for pain. Reliability therefore becomes an issue of "reliable in whose hands?" Reliability of many of the pain measurement methods have not extended in any realistic way beyond the reliability found by the original authors of the pain measurement methods.

A lack of clear reliability information should not prevent the clinician from using these methods, but it should alert the clinician to the possibility that a particular method may not be reliable with a particular patient or a group of patients. The clinician also should ensure that those who use the measurements for their own purposes will be aware of the limitations of these measurements.37

A difficult aspect of reliability is that the patient may have developed a different understanding of the pain problem and may give a different response from one examination to the next. It is equally important for the examiner to ask himself or herself whether the interpretation of the patient's responses differs from one

examination to the next. Both factors affect the reliability of the information being gathered.37

Perhaps it is worthwhile to re-examine the concepts of subjective and objective measurements. Sometimes the terms "objective" and "subjective" are concerned not with the reliability of a measurement, but with the nature of what is being measured. It could be argued that pain is a subjective phenomenon, but if it is measured reliably, the quality of the measurement would be objective.

Task. Use the previous sections to summarise all the criticisms of the different ways of measuring pain. Use as many DREAMS as possible