What is psoriatic arthritis?

Psoriatic arthritis¹ is an autoimmune disease (a disease that occurs when the immune system mistakenly attacks the body’s own healthy tissues).

It is a type of inflammatory arthritis that typically occurs in some people with psoriasis² (a skin disorder that causes skin cells to multiply much more quickly than is normal, causing red, patchy, and scaly skin). Psoriatic arthritis can also occur in people without a history of psoriasis but who may have relatives with the skin condition.

As its name suggests, psoriatic arthritis involves aspects of two separate diseases: arthritis (the inflammation of one or more joints in the body) and psoriasis. Psoriatic arthritis features the signs and symptoms of both of these conditions, including red, patchy, scaly skin and joint pain, swelling, and stiffness. Psoriatic arthritis can affect any joint in the body, and the symptoms can vary from person to person. The consistent inflammation caused by psoriatic arthritis can lead to permanent joint damage.

Psoriatic arthritis is most typically found in people ages 30–50, but it can begin as early as childhood, with males and females at equal risk for the condition. While psoriasis is often present before psoriatic arthritis develops, in some cases, arthritis can appear before the skin disorder.

Psoriatic arthritis is chronic, meaning it is long-lasting and develops over time. In some cases, it is only mild, causing occasional flare-ups. On other occasions, psoriatic arthritis can be severe and extremely painful. This usually leads to inflammation that causes fatigue and joint pain, swelling, and stiffness.

There is no known cure for psoriatic arthritis. However, there is a range of treatments available that can help relieve symptoms and slow the progression of the disease. Without proper treatment, psoriatic arthritis can cause permanent damage to the joints. The early detection, diagnosis, and treatment of psoriatic arthritis are critical in relieving the pain associated with the condition and preventing possibly more severe or harmful complications down the road.

How common is psoriatic arthritis?

An estimated 2.2% of Americans³ live with the skin condition psoriasis. Of that 2.2%, 30% have psoriatic arthritis (0.6% of all Americans) Of this group, about 20%⁴ will have a severe form of the disease, in which pain and swelling are bad enough to hinder their everyday life.

The most common type⁵ of psoriatic arthritis is polyarthritis, which involves 5 or more of the body’s joints. Its symptoms may also overlap with those of rheumatoid arthritis, including joint pain, swelling, and stiffness. The second most common form of psoriatic arthritis after polyarthritis is oligoarthritis.

The least common form of psoriatic arthritis is known as arthritis mutilans, which affects less than 5% of people with psoriatic arthritis. This rare condition causes severe inflammation in the joints of the hands and feet, resulting in deformation and movement difficulties.

Psoriatic arthritis causes

Psoriatic arthritis is an autoimmune disease⁶ (as are both psoriasis and some forms of arthritis). Healthy immune systems protect the body from foriegn substances that can cause infections or diseases. In people with autoimmune diseases, however, the immune system is unable to differentiate between foreign invaders and the body’s own cells and tissues. As a result, the immune system mistakenly attacks the body.

While we know how autoimmune diseases work, what exactly causes them to occur is uncertain. As with all autoimmune diseases, therefore, there is no one known cause of psoriatic arthritis. Instead, a combination of different factors⁷ is believed to play a role in the development of the disease, including.

• Family history: 40%⁸ of individuals with psoriasis or psoriatic arthritis have at least one blood relative with either of the diseases. You are also five times more likely to inherit psoriatic arthritis than you are to inherit psoriasis alone.

• Environmental factors: Diseases and physical factors, including streptococcus infection, HIV, stress, joint trauma, steroid use, and skin trauma, can all contribute to psoriatic arthritis.
• Obesity: Different studies have shown that 28%⁹ (to as much as 45%) of people with psoriatic arthritis are also obese. Additionally, carrying excess body weight has been linked with having more severe psoriatic arthritis and receiving less benefit from biological medications.

• Related diseases: The prevalence of some conditions, such as obesity, diabetes, hypertension (high blood pressure), and metabolic disorders, is increased in people with psoriatic arthritis.

Risk factors for psoriatic arthritis

The following risk factors¹⁰ may increase your risk of developing psoriatic arthritis:

• Medical history: Having psoriasis is a key risk factor for developing psoriatic arthritis.
• Age: People between the ages of 25 and 30 are the most likely to develop psoriatic arthritis.
• Family history: As previously mentioned, individuals with a family history of psoriatic arthritis are more likely to develop the condition themselves. Additionally, you can be 3–5 times more likely¹¹ to inherit psoriatic arthritis than psoriasis alone.

• Weight: Being overweight significantly increases your chances of developing psoriatic arthritis.
• Smoking: Studies have shown that women smokers were three times¹² more likely to develop psoriatic arthritis than nonsmokers. Additionally, past smokers have a 50% greater risk for the condition than those who have never smoked.

Psoriatic arthritis symptoms

The symptoms¹³ of psoriatic arthritis include those characteristic to both psoriasis and arthritis. These symptoms can range from mild (generally manageable with over-the-counter pain relievers) to severe (causing significant pain and interfering with daily life).

Common signs and symptoms of psoriatic arthritis include:

• Swelling in the fingers and toes: Painful, puffy swelling often appears in the fingers and toes—sometimes developing into deformities of the hands and feet—before noticeable joint symptoms occur.
• Stiff joints: Joints may be unusually stiff, especially after getting up in the morning or after sitting for a long period of time. This can contribute to mobility issues.
• Neck and back pain: Stiffness in the neck, upper back, lower back, or buttocks are usually signs of inflammation in the joints.
• Lower back pain: In some people, psoriatic arthritis results in the development of a condition called spondylitis, which causes inflammation of the joints between the spine’s vertebrae and between the spine and pelvis (called sacroiliitis).
• Enthesitis¹⁴: A main feature of spondylitis, this condition causes inflammation where the tendons or ligaments connect to bone, such as in the Achilles tendon.

• Nail pitting: Tiny dents and ridges appearing on the nails is often a tell-tale sign of psoriatic arthritis.
• Nail separation: At times, the entire nail can pull away from the bed itself and appear opaque yellow or green.
• Chest or rib pain: In some cases, psoriatic arthritis can cause shortness of breath and chest pain due to inflammation of the cartilage that connects the ribs to the breastbone (called costochondritis).
• Fatigue: As with many chronic conditions, psoriatic arthritis can cause inflammation and chronic pain, which can leave you feeling tired and fatigued.

Early signs of psoriatic arthritis

Some of early signs¹⁵ of psoriatic arthritis can be indicators of the condition in its early stages. Early detection of these signs and symptoms is the best way to begin treatment as soon as possible.

• Joint swelling and warmth: Along with some pain, the joints may be warm to the touch and swollen.
• Joint stiffness: This is especially common in the ankles, knees, fingers, toes, and lower back.
• Nail issues: These can be either the pitting or separation mentioned above.
• Dactylitis: This causes the entire finger or toe to swell and have a sausage-like appearance. This symptom is key to distinguishing psoriatic arthritis from rheumatoid arthritis, which may only affect one joint.
• Eye issues: This may be redness, irritation, pinkeye, or altered vision.
• Foot pain: The Achilles tendon and the bottom of the foot are two of the most commonly affected places in psoriatic arthritis.
• Fatigue: Exhaustion or feeling more tired than usual.
• Trouble moving the hands or fingers: Severe swelling can make normal everyday tasks difficult to complete.

If you experience any of the early signs or symptoms of psoriatic arthritis, see your healthcare provider. They will be able to assess your symptoms and provide the right diagnosis and treatment.

Psoriatic arthritis rash

A psoriatic arthritis rash¹⁶ typically looks the same as the rashes characteristic of psoriasis. The most common type of psoriasis rash causes raised patches of red skin with silvery-white colored scales, also known as plaques. These plaques may itch, hurt, or even burn. It is crucial not to scratch the plaques, as they are healing (and doing so can cause infections to occur).

Psoriatic arthritis rashes may come and go, and there may even be periods of the disease in which you are totally rash-free (called remission). Some factors, such as stress, infection, or injury (known as triggers) can cause you to break out in a rash (called a flare or flare-up).

Typically, psoriatic arthritis rashes appear on the elbows, knees, and scalp. However, a rash can appear anywhere on your entire body. These rashes are generally treated with creams and ointments, oral medications, or light therapy to reduce inflammation.

Complications from psoriatic arthritis

Especially when left untreated, psoriatic arthritis may cause a number of complications¹⁷:

• Uveitis: An eye condition that leads to swelling, redness, and blurring.
• Obesity: In some cases, the lack of mobility that arthritis causes can trigger factors that cause obesity.
• Metabolic syndrome: This includes high blood pressure (hypertension), high blood sugar, and high cholesterol.
• Type 2 diabetes: The risk of developing type 2 diabetes is significantly higher¹⁸ in individuals with psoriatic arthritis than in those without the disease.

• Cardiovascular disease:Cardiovascular disease is often seen as overlapping with psoriatic arthritis.
• Osteoporosis: Psoriatic arthritis accelerates bone loss and other factors that contribute to it, which can lead to osteoporosis (decrease in bone quality and density).
• Infections: Psoriatic arthritis can weaken the body's immune system, leaving you more prone to infections.
• Crohn's Disease: Psoriatic arthritis greatly raises the risk of developing this form of inflammatory bowel disease (IBD).