Pain and rheumatoid arthritis

Disease-modifying drugs reduce pain, but extra analgesia is usually needed, explains Professor Bruce Kidd.

Rheumatoid arthritis typically affects small joints such as the hands
Rheumatoid arthritis typically affects small joints such as the hands

Rheumatoid arthritis (RA) is an inflammatory disease of unknown cause, mainly affecting synovial joints. Typically, the small joints of the hands and feet are involved in a symmetrical pattern, although any joint may be affected.

Patients experience pain and symptoms such as fatigue and malaise. Less commonly, there may be involvement of other organ systems, including the eyes, skin, lungs and vasculature. RA is now considered to be a risk factor for IHD, leading to shortened life expectancy in many patients.

It is accepted that early treatment of RA is associated with better outcomes, although diagnosis of early synovitis remains a problem. Widely-used classification criteria do not facilitate the diagnosis of early disease, but may be more useful in identifying patients with a poorer prognosis.

Standard inflammatory markers may not necessarily be abnormal in early disease, although MRI and, more particularly, high-definition ultrasound are emerging as sensitive methods for demonstrating synovitis.

Pain mechanisms
The underlying mechanisms driving RA pain are not well understood. The disease is associated with a spectrum of mediators and growth factors, many of which act to sensitise joint nociceptors, leading to the mechanical hypersensitivity characteristic of the disorder.

Longer-term disease is associated with bone as well as soft tissue damage and mechanical factors are likely to be a cause of pain in many patients. Neuropathic syndromes can also occur on the basis of neuronal damage arising from nerve compression or neuropathy.

As with other chronic disorders, depression and other psychosocial factors make an important contribution to continuing pain perception and disability.

Treatment
One of the major changes in the management of RA has been a move away from a sequential stepwise approach to a focus on early intervention using combination therapy, with the ultimate goal being disease remission. Rapid referral to a specialist is strongly recommended for any patient with RA or suspected synovitis of undetermined cause.

Effective communication and education are vital from the outset, together with access to a multidisciplinary team that includes specialist occupational therapy and physiotherapy support. Psychological support services are also important.

Combination therapy
Evidence supports the early use of DMARDs, preferably within three months of the onset of persistent symptoms, to control pain and reduce disease activity and radiographic progression. Combination therapies using methotrexate and one other traditional DMARD, such as sulfasalazine plus short-term glucocorticoids, have been recommended.1-3

A further key development has been the introduction of quantitative composite scores of disease activity to monitor therapy. The recently introduced biological drugs, such as TNF-alpha inhibitors and rituximab, offer the potential to target specific components of the inflammatory cascade and seem to confer additional benefits over conventional DMARDs.

The indications for the use of different classes of DMARDs remain the subject of scrutiny. Guidelines for use will no doubt continue to evolve rapidly.4

Disease activity control
In some patients, adequate control of disease activity will result in symptom relief with no additional therapy required.

At present, however, most patients need additional analgesia because of inadequately controlled inflammation, mechanical damage or nerve injury.

NSAIDs or COX-2 inhibitors are effective, although concerns over cardiovascular toxicity have made long-term use less attractive. Paracetamol, codeine and compound analgesics are well-tolerated, potentially reduce the need for NSAIDs and are widely used.

Low-dose antidepressants are also being used more commonly to treat pain and the sleep disturbances associated with this disorder.

  • Professor Bruce Kidd is professor of clinical rheumatology, Barts and The London School of Medicine and Dentistry
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Item Code: MINT/PPR-12008

Date of Preparation: May 2012

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