Because pain is a subjective experience, it is difficult to quantify objectively. It is important to try to do so however, in order to assess the best treatment and to monitor benefits, various methods exist to help the clinician assess pain. However, he or she has to balance any inaccuracy of their techniques with the psychological profile of the patient, (e.g. he or she may be misled by patients who are perceived to have severe pain under-reporting pain).
There are many tools for assessing pain due to arthritic conditions, these may include the following types –
These can be subdivided into the following:
- Verbal rating scales (e.g. pain is severe, moderate, mild or non-existent). It is generally accepted that they lack sensitivity.
- Numerical rating scales (e.g. pain is scored on a scale of 0-3 where is no pain and 3 severe pain for instance). The stages of the score are ill defined.
- Return analgesic count. The number of tablets returned has been suggested as an indication of pain.
- Visual analogue scale (VAS). This has a high degree of reliability and validity with this group of patients. However, as the disease can affect many joints, it is important to ascertain what body area is being measured.
Two variations of the VAS are the:
- Graphic rating scale (with the words mild, moderate, severe along the line);
- The analogue chromatic continuous scale giving gradation of colour along the line (e.g. pale pink to dark red).
Unlike the above, these take into account the quality of the pain, describing, for example, sensory, evaluative and affective qualities, e.g. the McGill Questionnaire. One-third to one-half of patients with arthritis have described their pain as throbbing, shooting, tender or sharp regardless of disease severity  . There is, however, variability in the affective component of the pain described in the McGill Pain Questionnaire, e.g. in-patients with more severe arthritis used more intense affective responses .
The pain of arthritis and associated conditions can be significantly disabling and you may also see tools used that assess how the pain influences the patient’s ability to perform ‘normal’, everyday functions, e.g. the Health Assessment Questionnaire and the Modified Health Assessment Questionnaire.
In arthritic diseases pain is closely linked with inflammation; indeed the two may be indistinguishable. Therefore, other measurements of joint inflammation, e.g. early morning stiffness, grip strength and joint tenderness, can be useful
- Early morning stiffness – there are variations throughout the day in the nature and severity of pain experienced. In RA, pain is worse in the morning and with movement after long periods of inactivity accompanied by early morning stiffness. This is one of the diagnostic criteria for RA. However, it is relatively non-specific and difficult for the patient to quantify, in part because it wears off gradually.
- Grip strength – the more severe the inflammation the more severe the ‘functio laeso’ (loss of function) therefore the poorer the grip strength. However, in any destructive arthritis there will be associated loss of function and therefore grip strength will be reduced. To measure grip strength the patient squeezes a sphygmomanometer cuff inflated to 30 mmHg and the pressure achieved is recorded.
- Joint tenderness – one of the most used scales is the Ritchie Articular Index. This grades joints according to a patient’s response when the joint is squeezed with firm pressure. This scale is graded 0 – 3 (0 = no pain; 1 = pain; 2 = pain with wincing; 3 = pain with wincing and withdrawal). The score is summated and the maximum possible score is 78. The reduction in inflammation with treatment probably reflects well the reduction in pain.
- DAS28 (Disease Activity score) is an assessment of the number of swollen and tender joints of the shoulders, elbows, wrists, metacarpophalangeal joints, proximal interphalangeal joints and the knees. The Erythrocyte Sedimentation Rate (ESR) should be measured (in mm/hour). In addition, the patients general health (GH) or global disease activity measured on a Visual Analogue Scale of 100 mm (both are useable for this purpose) must be obtained. Using this data, the DAS28 can be calculated using a formula.
- Blood tests – the markers of inflammation, ESR and CRP, correlate loosely with the activity of disease in RA. They provide useful additional information, suggesting perhaps a change of therapy or increased dosage required for control of disease. In RA, chronic inflammation will also result in anaemia of chronic disease and a raised platelet count. However, as the disease progresses and cartilage is destroyed there may be little inflammation but significant amounts of pain. In monitoring OA these blood tests are of little help. In rheumatic conditions in general the ESR and CRP are of varied use, e.g. in gout and ankylosing spondylitis they are of no benefit at all.
- X-rays – X-rays give a record of past events. They do not indicate levels of inflammation currently and so the acute inflammation of RA will not correlate with pain. However, they do provide evidence of past destruction and this can provide useful information on planning surgical treatment.
- Occupational therapy assessment – the ability or inability to move is a primary clinical issue in the treatment of pain in arthritis. Pain is a contributing factor in limiting movement, which is also compromised by stiffness, inflammation, swelling and destruction of tissues in and around the joints. Work disability is also a concern in people with arthritis and it is important to include this variable in the assessment. Occupational therapy assessment can provide valuable detailed information on activities often limited by pain, e.g. managing stairs, managing in the kitchen, etc. It can give a particularly relevant assessment of patient’s immediate problems and define areas where help is required.
- Others – research continues to find the most accurate objective assessment. Attention includes analysing sleep disturbance due to pain, and as a research tool a sleep electroencephalogram may help.
- Burckhardt, C.S., 1985. The impact of arthritis on quality of life.. Nurs Res, Nurs Res 34, 11-6.
- Charter, R.A., Nehemkis, A.M., Keenan, M.A., Person, D., Prete, P.E., 1985. The nature of arthritis pain.. Br J Rheumatol,
- Br J Rheumatol 24, 53-60.