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Classifying Psoriatic Arthritis Based on Subtypes and Stages

Psoriasis is known as a condition where the skin cells start building up to form scales and itchy, dry patches. It is a chronic skin condition and is believed to be caused by an overactive immune system. Thirty percent of people who suffer from psoriasis end up developing psoriatic arthritis, which is an autoimmune condition that causes swelling, pain, as well as stiffness in the joints of the body. This type of arthritis is generally classified into five subtypes. The classification system of Psoriatic Arthritis depends on which joints of the body are affected and how many joints are affected. Psoriatic arthritis can either be mild or severe and can either involve one joint or many joints. Today we take a closer look at how to classify psoriatic arthritis and what it’s all about.

Classifying Psoriatic Arthritis Based on Subtypes and Stages

What is Psoriatic Arthritis?

Psoriatic arthritis is a rare condition that combines the condition of psoriasis with swollen and sore joints of arthritis. Psoriasis is a chronic condition of the skin which is caused by an overactive immune system. This skin condition causes the skin cells to multiply rapidly, up to even ten times faster than a normal rate. This causes the skin cells to build up into bumpy, red patches that are covered with white scales. Psoriasis can affect any part of the body but mostly appear on the elbows, knees, lower back, and the scalp. The symptoms of psoriasis include:

  • Inflammation
  • Flaking
  • Thick, white, silver or red patches of skin
  • Treatment of psoriasis includes light therapy, oral medications such as biologics, steroid creams, and occlusion.

Psoriatic arthritis causes pain, swelling, and stiffness in the body’s joints, similar to other forms of arthritis, except that these are accompanied by the symptoms of psoriasis.

Classification of Psoriatic Arthritis by Subtypes

Psoriatic arthritis is typically classified into five subtypes. This classification depends on which joints are affected and how many joints are impacted. The five subtypes, though, do not consider symptoms such as dactylitis, which is a condition where the fingers and toes swell up to look like sausages, and the condition of enthesitis, which is an inflammation of the areas around and near the ligaments and tendons. It is also possible that a person is diagnosed with one type of psoriatic arthritis, to begin with, and then it develops into another type at a later stage.

Let us take a look at these five subtypes of psoriatic arthritis.

Symmetric Psoriatic Arthritis

Symmetric psoriatic arthritis affects the identical joints on either side of your body. This means that both the right and left knees will be affected. Symptoms of symmetric psoriatic arthritis are similar to those of rheumatoid arthritis, but symmetric psoriatic arthritis is milder and also causes lesser deformity of the joints as compared to rheumatoid arthritis. However, symmetric psoriatic arthritis can cause disability. Nearly 50 percent of people suffering from psoriatic arthritis are diagnosed with the subtype of symmetric psoriatic arthritis, making it the most commonly occurring form of psoriatic arthritis.

Since it affects the same joints of both sides of the body, it is termed as symmetric. It also impacts five or more joints of the body, which can be anywhere on the body.

Asymmetric Psoriatic Arthritis

This condition is also referred to as asymmetric oligoarticular psoriatic arthritis. Asymmetric psoriatic arthritis affects the joint or joints only on one side of the body, hence the term asymmetric. The mirror joint on the other side of the body is not affected and remains healthy. The joints will feel sore and may also turn red. Asymmetric psoriatic arthritis is also a mild form of psoriatic arthritis and affects around 35 percent of patients having psoriatic arthritis. Asymmetric psoriatic arthritis can affect any joint in the body but does not usually affect more than four or five joints at one time.

Distal Interphalangeal Predominant psoriatic Arthritis

Nearly 20 percent of all cases of psoriatic arthritis involve the distal interphalangeal joints of the body. This refers to the joints at the ends of the fingers and the toes. Since these distal interphalangeal joints are the closest to the nails, the symptoms of this type of psoriatic arthritis typically involve changes to the nails, such as pitting, spotting, or physical separation from the nail bed.

Spondylitis Psoriatic Arthritis

In spondylitis psoriatic arthritis, inflammation reaches the spine, which causes stiffness and pain. Patients also experience difficulty in moving the lower back, the neck, the pelvis, and even the sacroiliac joints. The sacroiliac joints are the joints that are found between the sacrum, which is the bone that provides support to the spine and also connects to your tailbone. This type of psoriatic arthritis also affects the hands, legs, feet, arms, and the hips.

Psoriatic Arthritis Mutilans

Also referred to only as arthritis mutilans, this is the most severe type of psoriatic arthritis. Only five percent of all cases of psoriatic arthritis are affected by arthritis mutilans and the condition seriously damages the joints of the hands and the feet. Over a period of time, psoriatic arthritis mutilans can also cause a ‘telescoping’ of the digits. This means the fingers and the toes of the body become shorter, contributing to bone loss. Doctors, though, believe that this form of psoriatic arthritis is on a decline because treatment therapies are working very well to prevent the condition to reach this severe stage. Psoriatic arthritis mutilans can also cause in the neck and the lower back.

Classification of Psoriatic Arthritis by Stages

Apart from classifying the subtypes of psoriatic arthritis, the disease is also classified by various stages. For every person who is diagnosed with psoriatic arthritis, there is a different path for the disease to progress. Some people may experience only mild symptoms that may only have a limited impact on the joints. Others, though, may experience joint deformity as well as bone enlargement which may occur over a period of time.

There is no clear reason why certain people experience a rapid progression of the disease while others do not.

The stages of psoriatic arthritis include:

Early Stage Psoriatic Arthritis

This is the starting stage of arthritis. You experience mild symptoms such as a limited range of motion and joint swelling. The symptoms of arthritis can develop at the same time you start developing the skin conditions from psoriasis such as skin lesions. In some cases, the arthritis symptoms can occur years after you develop psoriasis. Treatment at this stage involves NSAIDs, which help relieve the pain and symptoms. Nonsteroidal anti-inflammatory drugs (NSAIDs), though, do not help slow down the progression of psoriatic arthritis.

Moderate Psoriatic Arthritis

Depending on the subtype of psoriatic arthritis you have, this moderate stage, considered to be the middle stage, will make the symptoms worsen and you will require more progressive treatment that NSAIDs. You will need DMARDs and biologics to help you manage the symptoms at this stage. These medications will help you find relief in the arthritis symptoms, and will also help in slowing down the progression of the damage caused by psoriatic arthritis.

Late Stage Psoriatic Arthritis

By the last stage of the disease, bone tissue in the body gets affected severely. You start to experience bone enlargement as well as joint deformity. The treatment at this stage will only help provide some relief from the symptoms while preventing the worsening of the complications.

Causes of Psoriatic Arthritis

In patients suffering from psoriatic arthritis, it is believed that their immune system starts to attack the joints and skin. Doctors are unsure about what exactly causes the immune system to attack the joints and skin, though it is believed to be a combination of environmental factors and genes.

Psoriatic arthritis runs in families and nearly 40 percent all patients diagnosed with one or the other subtype of psoriatic arthritis are known to have one or more relatives in the family already has the condition.

Environmental factors are also known to triggers the condition in people who have a tendency to develop psoriatic arthritis. These factors can include an injury, a virus, or extreme stress.

Symptoms of Psoriatic Arthritis

The symptoms of psoriatic arthritis differ from person to person. They can range from being mild to severe. When the condition goes into a remission phase, the person experiences relief for some time. Other times, though, the symptoms tend to get worse. The symptoms of psoriatic arthritis also depend on the particular subtype of arthritis you have.

Some of the generalized symptoms of psoriatic arthritis may include:

  • Morning stiffness
  • Tender and swollen joints on one side or both sides of the body
  • Swollen fingers and toes
  • Painful muscles and tendons
  • Flaky scalp
  • Fatigue
  • Nail pitting
  • Scaly skin patches, which worsens during the joint pain flare-up
  • Eye redness or conjunctivitis
  • Uveitis or eye pain
  • Separation of the nail from the nail bed

In the case of spondylitis psoriatic arthritis, the following symptoms may also be experienced:

  • Swollen toes or fingers
  • Spinal stiffness and pain
  • Pain and swelling accompanied by weakness in the hips, knees, legs, ankles, feet, hands, elbows, wrists, and other joints
  • Symmetric psoriatic arthritis can affect five or more joints of the body on both sides, while asymmetric psoriatic arthritis tends to affect less than four or five joints, on either side of the body, generally on opposing sides.

In cases of psoriatic arthritis mutilans, the joints of the body can become deformed and it also shortens the affected fingers and toes. Distal psoriatic arthritis also causes pain and swelling, but primarily to the end joints of the fingers and toes.

Treatment of Psoriatic Arthritis

There is no cure for psoriatic arthritis and the purpose of the treatment is to manage and improve the symptoms of psoriatic arthritis such as joint inflammation and skin rash. There are many types of treatment options and it typically includes one or more of the below-mentioned methods:

NSAIDs (Nonsteroidal anti-inflammatory drugs). These medications are known to help manage joint pain and swelling. There are also over-the-counter options that include medications such as Alevel (naproxen) and Advil (ibuprofen). If over-the-counter medications do not prove to be efficient, then your doctor will prescribe a higher dosage of NSAIDs.

However, if not used properly, NSAIDs may cause the following side effects:

DMARDs (Disease-modifying anti-rheumatic drugs). These are medications that help reduce inflammation, thus, preventing damage to the joints and also helping slow down the progression of the disease. These medications are given either through an injection or through infusion. Some of the most commonly used DMARDs for psoriatic arthritis include:

  • Azulfidine (sulfasalazine)
  • Trexall (methotrexate)
  • Arava (leflunomide)
  • Otzeia (apremilast) is one of the newer DMARD that is taken orally. The medication works by blocking the enzyme that primarily causes inflammation, known as phosphodiesterase 4.

Some of the commonly occurring side effects of DMARD include:

Biologic drugs. Biologic drugs are also known as tumor necrosis factor-alpha inhibitors. They block the effects of the tumor necrosis factor-alpha protein in the body, thus decreasing inflammation and providing relief in symptoms like swollen joints and improving joint stiffness.

There are many other types of treatments available that are used to manage the symptoms of psoriatic arthritis and your doctor will work together with you to determine the best treatment plan that suits your particular condition.

Outlook for Psoriatic Arthritis

Similar to the progression of the disease, even the outlook of psoriatic arthritis varies from person to person. Some people who have mild symptoms, only experience flare-ups from time to time. Others end up experiencing more frequent flare-ups as their symptoms are severe and debilitating.

The more severe your symptoms, the more likely that psoriatic arthritis will impact your ability to move about. Patients who have very severe symptoms may find it hard to walk, run, climb stairs, and even do daily activities.

The outlook for psoriatic arthritis gets affected by:

  • If you are diagnosed at a young age
  • If your condition was already severe at the diagnosis stage
  • A lot of your skin is covered in rashes
  • Many people in your family suffer from the condition

If you want to improve your outlook, you should follow the prescribed treatment that your doctor has set for you. Working together with your doctor will help you find the correct treatment plan that meets your individual requirements.

Also Read:


Moll, J.M.H. and Wright, V., 1973, January. Psoriatic arthritis. In Seminars in arthritis and rheumatism (Vol. 3, No. 1, pp. 55-78). WB Saunders.

Taylor, W., Gladman, D., Helliwell, P., Marchesoni, A., Mease, P. and Mielants, H., 2006. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology, 54(8), pp.2665-2673.

Gladman, D.D., Antoni, C., Mease, P., Clegg, D.O. and Nash, P., 2005. Psoriatic arthritis: epidemiology, clinical features, course, and outcome. Annals of the rheumatic diseases, 64(suppl 2), pp.ii14-ii17.

Ritchlin, C.T., Kavanaugh, A., Gladman, D.D., Mease, P.J., Helliwell, P., Boehncke, W.H., De Vlam, K., Fiorentino, D., Fitzgerald, O., Gottlieb, A.B. and McHugh, N.J., 2009. Treatment recommendations for psoriatic arthritis. Annals of the rheumatic diseases, 68(9), pp.1387-1394.

Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 19, 2019

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