What is undifferentiated arthritis? Why do my joint pains have no diagnosis?

Rheumatologists are experts who deal with diagnosing and treating various kinds or types of arthritis. However, as always in medicine, things are not always clear cut or black & white.

What is undifferentiated arthritis ?

In many cases (almost 20 % of arthritis), despite all the investigations, the type of arthritis is unclear. But the treating rheumy is sure that the patient has inflammatory arthritis. We will call that patient to have undifferentiated arthritis. This basically means that the patient has arthritis of some sort, but it hasn’t evolved into a specific type.

Rheumatology diseases are broadly classified as diseases with a lot of inflammation (redness, swelling, warmth etc) or diseases with very little or no inflammation. When inflammation is in joints we call it arthritis. Eg. of inflammatory diseases: Rheumatoid arthritis, Lupus, Gout, Ankylosing spondylitis, scleroderma, myositis, vasculitis etc. Eg. of non-inflammatory (or less inflammatory) diseases : Osteoarthritis, fibromyalgia, sof tissue rheumatism issues, hypermobility syndrome etc

What is Rheumatology & arthritis ? Who is a Rheumatologist?
Does increase in uric acid cause joint pains ?
Should I try Ayurveda for curing my rheumatoid arthritis ?

What is the difference between label of inflammatory arthritis and label of non-inflammatory arthralgias?

Many patients come to the rheumatology clinic with joint pains and generalised body pain.

The first job of the rheumatologist in a patient with joint or body pain is to decide whether there is significant inflammation (redness, swelling, warmth) in joints (or other organs) or not. The treatment of inflammatory arthritis / diseases (eg : rheumatoid arthritis, ankylosing spondylitis, lupus (SLE), gout, myositis etc) is very different from patients having non-inflammatory pains.

In many cases, the rheumatologist is sure that the patient has arthritis with a lot of inflammation. However, the type of such inflammatory arthritis is not clear by any method. Such patients are given a label of ‘undifferentiated arthritis’. The rheumatologist may plan to give strong anti-inflammatories to such patients to control disease and prevent joint damage.

The patients with non-inflammatory pains may be diagnosed to have vitamin deficiencies (eg vitamin D deficiency), fibromyalgia, osteoarthritis, local issue like tennis elbow etc. (Osteoarthritis patients might have some inflammation, but not as much as rheumatoid arthritis patients, hence it is still classified as non-inflammatory most times). If the patient has joint pains and no particular cause is found, we might use the label of non-inflammatory arthralgias (joint pains) under evaluation.

In practice, undifferentiated (inflammatory) arthritis is a label given to at least 10-20 % of rheumatology patients. It is not always necessary or possible in rheumatology to know the exact type / variant of the disease. Hence often words like possible, probable, undifferentiated, seronegative (negative reports of RA) etc are used in rheumatology.

Why do Rheumatologists use steroids to treat Rheumatoid Arthritis ?
Which Ayurvedic oil is best for knee / joint pain ?
Why you should not stop eating chana dal (or other lentils) in gout, increased uric acid and arthritis ?
So most rheumatologists will generally use the following terms in specific scenarios given below. (please understand that these terms may be used differently by different rheumatologists. clarify with your rheumy on what diagnosis / label they have given and any reason for the same),

1) Undifferentiated inflammatory arthritis / inflammatory arthritis under evaluation

This label is only given when there are clear signs of inflammation. The rheumatologist in such cases plans to treat patients with anti-inflammatories like DMARDS (disease modifying ant–rheumatic drugs). This is because if they are not treated they might develop severe joint damage like in untreated rheumatoid arthritis. They will also keep a close watch on these patients to see whether they develop any new features. If this happens, they might be classified into one of the more recognised types of inflammatory arthritis (eg : rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis etc).

A good rheumatologist will always re-valuate patients for new developments when the diagnosis is not clear. They might still start the treatment in such patients if there is lot of inflammation and disease is severe.

2) What is seronegative rheumatoid arthritis?

Many times, undifferentiated arthritis patients with negative rheumatoid arthritis tests (RA factor, anti- CCP) have a pattern of arthritis exactly like rheumatoid arthritis. Such patients may be given a label of seronegative rheumatoid arthritis instead of rheumatoid arthritis. As mentioned above, all undifferentiated arthritis patients will be rechecked at regular intervals. This is to make sure that they do not fit into a specific type of inflammatory arthritis disease.

Some patients have inflammatory arthritis with a pattern very close to rheumatoid arthritis, but have negative rheumatoid arthritis tests (RA factor, Anti CCP). The rheumatologist might use a label of seronegative rheumatoid arthritis rather than undifferentiated arthritis in such cases.

3) Non-specific joint or bodily pain / non-inflammatory arthralgias under evaluation/ watch for future evolution

This label is used when there is no clear evidence of significant inflammation being present. The rheumatologist may not be able to give a clear label of osteoarthritis / fibromyalgia etc in such cases. He / she also doesn’t plan to give strong anti–inflammatory drugs (like steroids and DMARDS) in such cases. They might give non-steroidal inflammatory drugs (NSAID) to such patients for pain along with other non-medicinal measures like exercise etc. They may closely watch these patients to look for evolution to another disease (inflammatory or non-inflammatory).

Rheumatologist does come across many patients daily who have pains without clear signs of inflammation in any organ. In such cases, rheumatologist might ask the patient to revisit in a few weeks. A good rheumatologist will always wait and watch (before giving any major medications) in cases with unclear diagnosis. This is especially the case, if the inflammation is not very severe.

So what do rheumatologists do when the patient has undifferentiated (inflammatory) arthritis or non-inflammatory pains ?

• If there is lot of inflammation in joints (or other organs) the rheumatologist will proceed with treatment. Though it is good to know the type of arthritis / inflammatory disease, it is not always possible to know the type. The treatment in such cases will be similar to any inflammatory arthritis eg : Rheumatoid arthritis. The only difference is that rheumatologist will try to use only those drugs which generally work in all types of arthritis / inflammatory diseases.
• The rheumatologists has to give therapies based on clinical scenarios alone in many patients. Just because a patient has been labelled with undifferentiated diseases, doesn’t mean the therapy is based on trial and error. There are still proper pathways to treat such patients.
• In some bordeline cases, the rheumatologist might give a short course of steroids and / or anti-inflammatories (like NSAID’s). Then they reasess patients in few weeks to see whether patient needs any long term therapy.
• If the patient appears to have only pains without inflammation without a clear diagnosis, the rheumatologist may again wish to try exercise, pain relieving agents etc and ask the patient to revisit in few weeks time.
• In many cases rheumatology patients evolve and picture becomes more clear in 3-6 months. Many undifferentiated arthritis or joint pains which start suddenly might completely go away in 3-6 months on their own. In such cases rheumatologists will help to just support patients in managing their symptoms, till things resolve on their own.

Even in undifferentiated or unclear cases the rheumatologist can often form plan to treat. This plan is not a trial and error plan. They formulate such plan based on a variety of factors including their experience in dealing with such kind of cases in past. As mentioned above, 10-20 % cases in rheumatology remain undifferentiated.