People with psoriasis have an increased risk of developing psoriatic arthritis (PsA). New research shows that psoriasis severity and body surface area play a role in determining the extent of the risk.

Psoriasis is a chronic, autoimmune disease that affects the skin, causing dry, itchy patches with a covering of scales. In the United States, more than 7.5 million adults are living with this skin condition, which equates to about 3% of the adult population.

PsA is a chronic, inflammatory type of arthritis that leads to symptoms such as joint pain, stiffness, and swelling. Although it is possible to develop PsA without first having psoriasis, up to 34.7% of people living with psoriasis worldwide develop PsA.

The collective name for these two conditions is psoriatic disease. Researchers have looked into the link between these conditions and how they affect one another. Of particular interest are predictive symptoms that may indicate whether a person with psoriasis will also develop PsA.

More recently, researchers have investigated how the severity of psoriasis may affect the onset of PsA. A 2021 study showed a correlation between more severe cases of psoriasis and the development of PsA.

This article explores what experts know about the connections between psoriasis severity and PsA.

Over the years, researchers have studied the connection between psoriasis and PsA. Part of what they have looked for is trends in symptoms that may predict the likelihood that a person with psoriasis will also develop PsA.

As more than one-third of people living with psoriasis may also develop PsA, understanding the risk factors to look for may help doctors diagnose the joint condition sooner. Earlier diagnosis and treatment of PsA may lead to better outcomes and improved quality of life.

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Certain psoriasis symptoms may increase a person’s risk of developing PsA. Psoriasis lesions in the following places may indicate an increased risk of PsA.

  • nails
  • scalp
  • skin folds

PsA symptoms may appear mild at first. As a result, people with psoriasis should look out for the following symptoms as an indicator of PsA development.

  • increased psoriasis severity
  • joint pain
  • joint stiffness and swelling
  • nail dystrophy
  • swelling in the fingers or toes (dactylitis)

Research is beginning to show that the severity of a person’s psoriasis may indicate an increased risk of developing PsA.

In a 2021 study, researchers noted that severe psoriasis increased a person’s risk of developing PsA. However, they cautioned that these findings might not be generalizable to the larger population.

In another 2021 study, researchers suggested that the total body surface area that psoriasis covers may help predict the likelihood of developing PsA. The study authors also noted depression and obesity as additional risk factors.

The Global Healthy Living Foundation notes that although anyone living with psoriasis can develop PsA, psoriasis that covers a larger area of the body puts people at higher risk.

The organization also lists additional risk factors that could influence whether a person with psoriasis goes on to develop psoriatic arthritis. These factors include:

  • age
  • genetics and family history
  • environmental factors
  • obesity
  • smoking status

Growing evidence suggests that the severity of psoriasis symptoms, including how much of the body they affect, directly corresponds with the risk of developing psoriatic arthritis.

People who receive a diagnosis of psoriasis can talk with a doctor about their risk of developing PsA. They should also inform the doctor if they experience any joint symptoms that may indicate PsA.