What is Psoriatic Arthritis?
Psoriatic arthritis is inflammatory joint disease that occurs in people with psoriasis. It can affect the joints, the tendon insertions, the spine and the nails, and around one in seven patients develops the arthritis before any skin rash appears. Early treatment prevents joint damage and treats skin and joints together.
Also called: PsA
Who gets Psoriatic Arthritis?
Between one in five and one in three people with psoriasis develop psoriatic arthritis, usually five to ten years after the skin disease begins — but in about 15 per cent the joints are affected first, and the psoriasis may be limited to the scalp, navel or the crease between the buttocks where it is easily missed. Men and women are affected equally, most commonly between 30 and 50. Nail changes — pitting, ridging or lifting of the nail from its bed — are strongly associated with joint involvement.
What are the symptoms of Psoriatic Arthritis?
Not everyone has every symptom below, and having one does not confirm the diagnosis. These are the features that most often lead to assessment:
- Painful, swollen joints, often asymmetrical and sometimes affecting the joints closest to the fingertips
- Swelling of an entire finger or toe so that it looks like a sausage (dactylitis)
- Heel pain, or pain where tendons attach to bone at the elbow, knee or pelvis (enthesitis)
- Lower back and buttock pain with morning stiffness that eases with movement
- Nail pitting, ridging, thickening or separation from the nail bed
- Psoriasis of the skin or scalp, sometimes minimal or hidden
- Eye redness and pain from uveitis
- Profound fatigue
How is Psoriatic Arthritis diagnosed?
Diagnosis is clinical, made on the combination of inflammatory joint symptoms with psoriasis or nail changes, or a first-degree relative with psoriasis. There is no confirmatory blood test — rheumatoid factor and anti-CCP are usually negative, and their absence in someone with psoriasis and joint swelling supports the diagnosis rather than arguing against it.
Inflammatory markers may be normal even in active disease. Ultrasound and MRI show enthesitis and dactylitis, and X-rays of the hands, feet and pelvis may show characteristic changes including sacroiliitis.
A skin and scalp examination is part of the assessment, including areas patients do not think to mention.
How is Psoriatic Arthritis treated?
Treatment is chosen to cover whichever domains are active — peripheral joints, spine, entheses, skin and nails do not all respond to the same drugs.
Mild peripheral disease may respond to a non-steroidal anti-inflammatory and a local injection. Persistent joint disease is treated with methotrexate, leflunomide or sulfasalazine.
Spinal involvement and enthesitis do not respond well to conventional DMARDs and are treated with biologics. TNF inhibitors, interleukin-17 and interleukin-23 blockers, and JAK inhibitors are all effective; the choice depends on skin severity, spinal involvement, eye disease and whether there is co-existing inflammatory bowel disease.
Joint and skin care are coordinated with dermatology, since one treatment often serves both.
Living with Psoriatic Arthritis
Psoriatic arthritis carries a higher rate of metabolic syndrome, fatty liver and cardiovascular disease than the general population, so weight, blood pressure, lipids and glucose are monitored alongside the joints. Weight reduction measurably improves both skin and joint disease and increases how well biologics work.
When should you see a rheumatologist?
Anyone with psoriasis who develops joint pain, heel pain, a swollen finger or toe, or morning back stiffness should be assessed — and anyone with those symptoms should be asked about psoriasis in the family.
Common questions about Psoriatic Arthritis
Can I have psoriatic arthritis without psoriasis?
Yes. In roughly 15 per cent of patients the joint disease comes first, sometimes years before the skin. A family history of psoriasis, nail pitting, or psoriasis hidden on the scalp or in skin folds supports the diagnosis.
Why is my whole finger swollen rather than just the joint?
That is dactylitis, and it is characteristic of psoriatic arthritis. The whole digit swells because tendons and their sheaths are inflamed alongside the joints. It is one of the most specific signs of the condition.
Does treating my skin also treat my joints?
Some treatments do both — several biologics used for psoriasis are also effective for psoriatic arthritis. Others treat one and not the other; methotrexate helps both, while some topical and light treatments help only the skin. Joint disease needs its own assessment.
Is psoriatic arthritis worse than rheumatoid arthritis?
Neither is uniformly worse. Untreated, both can damage joints permanently. Psoriatic arthritis more often affects the spine and tendon insertions and carries greater metabolic risk; rheumatoid arthritis more often affects the small joints symmetrically.
This page is general information to support a consultation. It is not a diagnosis, and it does not replace an assessment by a doctor who has examined you.