How is psoriatic arthritis different from rheumatoid arthritis?
Both are inflammatory types of arthritis, but psoriatic arthritis usually occurs with psoriasis and may cause swollen whole fingers or toes, nail changes, tendon pain and spine involvement, often affecting joints unevenly. Rheumatoid arthritis typically affects small joints of both hands and feet symmetrically and is often linked with specific blood antibodies.
What do they have in common?
Psoriatic arthritis and rheumatoid arthritis are both caused by the immune system attacking the joints, causing pain, swelling, stiffness and, without treatment, possible joint damage. Both can cause fatigue and prolonged morning stiffness, and both are treated with medicines that control inflammation.
Early diagnosis matters for both conditions, because starting effective treatment early helps protect joints and function.
What features suggest psoriatic arthritis?
The CASPAR classification criteria, developed from data on 588 people with psoriatic arthritis and 536 people with other inflammatory arthritis, identify psoriatic arthritis in people with inflammatory joint disease who score at least 3 points from these features: current psoriasis (2 points), a personal or family history of psoriasis, nail changes, dactylitis, new bone formation near joints on X-ray and a negative rheumatoid factor test 2.
Dactylitis means a whole finger or toe swells like a sausage. Psoriatic arthritis also commonly causes enthesitis, inflammation where tendons attach to bone, such as at the heel, and it can affect the end joints of the fingers and the spine. The CASPAR criteria were 98.7 per cent specific and 91.4 per cent sensitive in the development study 2.
What features suggest rheumatoid arthritis?
Rheumatoid arthritis usually affects several small joints of the hands and feet on both sides of the body, such as the knuckles and middle finger joints, and the wrists. Classification criteria consider the number and site of affected joints, blood tests for rheumatoid factor and anti-citrullinated protein antibodies, inflammatory markers and symptom duration, with 6 or more points out of 10 indicating definite rheumatoid arthritis 1.
The end joints of the fingers and the lower spine are rarely affected in rheumatoid arthritis, which helps distinguish it from psoriatic arthritis.
Can psoriatic arthritis occur without skin psoriasis?
Yes. In some people, joint symptoms appear before skin psoriasis, or the psoriasis is mild and hidden, for example on the scalp, in the navel or between the buttocks. A family history of psoriasis or nail changes such as pitting may provide clues.
A rheumatologist examines the skin and nails as well as the joints when psoriatic arthritis is suspected.
How are the treatments different?
For rheumatoid arthritis, European recommendations advise starting methotrexate with short-term glucocorticoids, and adding a biological or targeted synthetic medicine if the target is not reached within three to six months, particularly when poor prognostic factors are present 3.
For psoriatic arthritis, European recommendations propose anti-inflammatory drugs and local steroid injections initially, rapid use of conventional disease-modifying drugs for people with poor prognostic factors, and biological medicines if needed. When the spine is mainly affected, a TNF or IL-17A inhibitor is recommended first, and skin involvement is considered when choosing treatment 4.
What role does rehabilitation play?
In both conditions, exercise helps maintain joint mobility, muscle strength, cardiovascular fitness and bone health. Hand therapy, splints, joint protection advice and footwear or insoles for foot involvement can reduce pain and improve function.
Programmes are adjusted to disease activity: gentle mobility during flares and progressive strengthening and aerobic exercise when inflammation is controlled.
How do these conditions affect heart health and wellbeing?
Both psoriatic arthritis and rheumatoid arthritis are linked with a higher risk of heart disease, related to ongoing inflammation and other risk factors. Controlling inflammation, not smoking, staying active, maintaining a healthy weight and checking blood pressure, cholesterol and blood sugar are important.
Fatigue, low mood and anxiety are common in both conditions. Discussing these with the rheumatology team can lead to support such as psychological therapies, exercise programmes and help with work.
When should joint symptoms be assessed?
Seek assessment for joint swelling lasting more than a few weeks, prolonged morning stiffness, a swollen sausage-like finger or toe, or joint pain in someone with psoriasis.
A single hot, swollen joint with fever needs urgent assessment to exclude infection.
Frequently asked questions
Can blood tests tell psoriatic and rheumatoid arthritis apart?
Blood tests help. Rheumatoid factor and anti-CCP antibodies are often positive in rheumatoid arthritis and usually negative in psoriatic arthritis, but results must be interpreted with symptoms.
Is psoriatic arthritis less serious than rheumatoid arthritis?
Not necessarily. Both can cause joint damage without treatment, and severity varies between individuals.
Does psoriatic arthritis affect the back?
It can. Some people develop inflammatory back pain and stiffness, which influences treatment choices.
Can I have both psoriasis and rheumatoid arthritis?
Yes, it is possible. A rheumatologist uses clinical features and tests to determine the type of arthritis.
Sources
- 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative — Arthritis & Rheumatism (2010)
- Classification criteria for psoriatic arthritis: development of new criteria from a large international study — Arthritis Rheum (2006)
- EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update — Annals of the Rheumatic Diseases (2023)
- EULAR recommendations for the management of psoriatic arthritis with pharmacological therapies: 2019 update — Annals of the Rheumatic Diseases (2020)
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