Quality of life is dependent on treatment of both joint and skin symptoms in PsA

Treating both joint and skin symptoms maximises quality of life for people with psoriatic arthritis.

Psoriatic arthritis (PsA for short) is a chronic inflammatory disease that affects a person’s joints and other parts of the body, including the spine, skin, and tissues joining tendons and ligaments to bones (called entheses). It gets its name from the link between this type of arthritis and a skin condition called psoriasis, which causes red, flaky, crusty patches of skin covered with silvery scales. The inflammation in psoriatic arthritis often causes swelling of the fingers, toes or bigger joints (such as the knee). This can result in pain, fatigue and mobility issues. As a result, psoriatic arthritis can affect people’s quality of life, which is a measure of your physical, mental, emotional and social wellbeing.

Ixekizumab (pronounced ix-ee-KIZ-ue-mab) belongs to a group of medicines called biologic disease modifying antirheumatic drugs (sometimes called biologics or bDMARDs). These medicines work by targeting specific chemical messengers in the body that cause inflammation, in this case a molecule called interleukin-17 (shortened to IL-17). The aim of this treatment is to reduce inflammation in the body, improve symptoms, and prevent the disease from getting worse.

What did the authors hope to find?
The authors wanted to see whether improvements in joint and skin symptoms affect quality of life in people taking ixekizumab.

Who was studied?
The study included 402 people with psoriatic arthritis. The average age was 49, and most of the people taking part were male. Everyone had more than 3% of their body surface area affected by psoriasis.

How was the study conducted?
This study was a planned analysis of data already collected in two randomised controlled trials called SPIRIT-P1 and SPIRIT-P2. In these two clinical trials, people were randomly assigned to receive either ixekizumab or placebo (a dummy treatment which has no physical effect on the body). Using chance in this way means that the groups are similar and can be compared to see the effect of the medicine. The authors used a computer model to look for the the relationship between quality of life and improvements in joint and skin symptoms after 24 weeks of treatment with either ixekizumab or placebo.

What were the main findings of the study?
The main finding was that people who had improvement in skin activity but less improvement in joint activity still experienced an increase in quality of life. People who had improvement in joint activity but less improvement in skin activity also experienced better quality of life. The greatest increase in quality of life was seen in people who had improvement in both their skin and joints.

Are these findings new?
Yes. Although doctors would expect people’s quality of life to increase with improvements in skin and joint health, this has never been studied. This is the first proof that the best way to improve quality of life in people with psoriatic arthritis is to treat both skin and joint symptoms.

What are the limitations of the study?
Because this study was done in people with psoriatic arthritis, the amount of skin affected was generally less than in people with psoriasis and no arthritis in their joints, and this may have had an impact on the results.

What do the authors plan on doing with this information?
Psoriatic arthritis affects more than just the skin and joints. The authors plan to look at the contribution of other aspects of the disease on quality of life.

What does this mean for me?
If you have psoriatic arthritis, you might experience lower quality of life than other people without the disease. Different aspects of your disease can have an impact on quality of life – for example, skin versus joint symptoms. If some aspects are more important to you than others, you should talk to your doctor to make sure that you
get the right treatment and support that will deliver the best results for you.

If you have any concerns about your disease or its treatment, you should talk to your doctor.

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Date prepared: August 2019
Summary based on research article published on: 31 May 2019
From: Kavanaugh A, et al. The contribution of joint and skin improvements to the health-related quality of life of patients with psoriatic arthritis: a post hoc analysis of two randomised controlled studies. Ann Rheum Dis 2019;78:1215–19. doi:10.1136/annrheumdis-2018-215003

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