Arthritis is only arthritis when there is clinical evidence of arthritis …

By Dr Johannes C Nossent
Professor of Rheumatology, University of Western Australia
Consultant Rheumatologist Sir Charles Gairdiner Hospital

Although it has become common to designate all joint symptoms as ‘arthritis’, this incorrect terminology can create significant confusion in clinical practice and in communication between medical professionals.

Pain in the joint areas is a well known, frequently presenting complaint in general practice and can originate from changes to peri articular soft tissue structures (classified as arthralgia) and/or intra-articular changes such as inflammation of the synovial joint lining (synovitis, classified as arthritis).

History taking and joint examination are the only tools needed to make the simple but important distinction between arthritis and arthralgia in the evaluation of a patient with joint pain. The clinical distinction between arthralgia and arthritis has significant practical implications because the pathway for patients with arthralgia differs from the pathway for patients with arthritis.

Arthritis literally means inflammation of a joint and arthritis thus should only be diagnosed, when joint/s are shown to be inflamed. Arthritis is in most cases detectable by clinical examination of joints but may sometimes require high resolution imaging (ultrasound or MRI). Finding arthritis/synovitis is a critical step in patient evaluation, similar to finding low haemoglobin levels in a patient with fatigue, and indicates a need to establish the underlying cause of arthritis.

To establish a cause of the arthritis (e.g. immune mediated such as rheumatoid arthritis or psoriatic arthritis or crystal induced such as gout or pseudogout, infectious), only limited and targeted investigations need to be performed to decide on the best course of management. This process is again, similar to finding the cause of anaemia in a fatigued person.

Not finding signs of arthritis is an equally important step in the evaluation of patients with joint pain as it suggests pain is arising from peri articular structures including bone, muscles, tendon insertion points (enthesis) and ligaments. These abnormalities can often be detected on examination (eg Heberden’s nodes with osteoarthrosis) or triggered (Achilles tendon or insertional elbow or knee pain). Periarticular causes of pain can be classified as soft tissue pain, can be further visualised with imaging (ultrasound/MRI), and management is through allied health referral if needed.

It does not require further serological investigation.

The Choosing Wisely campaign is a timely reminder of the limited diagnostic utility of most tests performed in the name of a ‘rheumatology screen’. It is important to realise that all rheumatic diseases are diagnosed on clinical grounds. The so-called “Rheum Screen” at its worst may include tests for ANA, ANCA, RF, ACPA, uric acid and HLA-B27, none of which are sufficiently specific to be diagnostically helpful. Specificity varies between five and 25 percent due to the large number of false positives. This is not compatible with judicious use of public Medicare funding.

In 2014-15, over $10 million dollars was spent on ANA testing alone . This already difficult situation is further impacted by the lack of standardisation between the current pathology providers in WA, where different assays and cut-off values are used for these tests.

Therefore, in the absence of a clinical finding of arthritis/synovitis, no further serological testing is required. For patients with arthritis, simple descriptors are often sufficient to initiate appropriate first line management and specialist referral. For example, in the patient with acute monoarthritis, one considers gout and /or infection and performs joint aspiration, whereas in the patient with chronic small joint polyarthritis one considerers rheumatoid arthritis, and can request anti-CCP antibody testing (more specific and thus preferred over rheumatoid factor).

In summary, normal joints upon examination exclude arthritis and do not require autoimmune blood testing. In patients with synovitis, only limited and targeted blood testing is needed. See also the recently published Arthritis HealthPathway for more information.