Psoriatic Arthritis

Psoriatic Arthritis (PsA) is a disorder of the immune system that affects the skin and joints, causing joint pain, stiffness, swelling and deformity. It typically appears in people who have psoriasis, a chronic disorder characterised by scaly, reddish skin rash that usually appears on the elbows, shins and scalp. The nails may appear thickened, rugged and cloudy.

A healthy immune system releases antibodies that fight off viruses and bugs that invade the body. In autoimmune disorders such as psoriatic arthritis, the body turns against its own tissues, sending white blood cells to attack and inflame the skin, the joint capsule (synovium) and the tendon around the joints. The commonly affected joints are the hand joints, wrists, elbows, knees, ankles and toes. 

Fingers may also inflame and swell up to be shaped like sausages (dactylitis). Over time, the inflammation invades the cartilage and bone, causing joint damage or even shortening of fingers in severe cases. It also affects the spine in some patients, causing stiffness and pain. As joint damage may occur early in the process of the disorder, diagnosing psoriatic arthritis as quickly as possible and treating it properly is important.

PsA is a systemic disorder that can affect other organs in the body, like the eye, the heart valve and the bowel. The inflammation is chronic and can lead to heart disease.

PsA affects men and women equally. The peak age of onset is between 30 and 55 years old. It can be diagnosed during childhood too. Most people develop psoriasis first, then arthritis.

PsA typically appears about 5-10 years after the onset of psoriasis. Symptoms are pain, swelling and stiffness of joints, especially in the mornings and symptoms do not go away for weeks to months. Some patients may have back, neck or buttock pain. Fingers and toes may also be painful and swell up like sausages (dactylitis).

Other symptoms include fatigue, malaise, loss of weight and appetite – and these are dependent on the severity of the disorder. In advanced PsA, there will be a shortening of the joints, joints becoming damaged and crooked, fingers become shortened and the back becomes bent with stiffness.

Although scientists are not certain about the exact cause of PsA, one can prevent the disabilities caused by PsA through early diagnosis and treatment. A healthy balanced diet and moderate regular exercise are also helpful in preventing complications. If you have psoriasis and are now experiencing joint pain and aches, please seek advice from a rheumatologist. PsA will cripple a patient if the diagnosis is delayed or if the patient does not abide by his prescribed medications.

Like most forms of autoimmune disorders, PsA has no known single cause and doctors don’t know exactly what triggers it. Researchers believe PsA is linked to genetic factors and can be triggered by an infection, injury or stress. In 70% of patients, skin disorders (psoriasis) start before joint problem. Therefore, if you have psoriasis it is important to tell your dermatologist if you have any aches and pains. Not everyone who has psoriasis develops PsA. Only 15-35% of them develop PsA.

Diagnosis is made by an experienced doctor (rheumatologist) through a detailed history and physical examination for signs of joint and tendon inflammation, psoriasis and nail changes. Your doctor will also look for psoriasis nail lesions and skin lesions that might be in hidden places (under the hairline, arm pit, at the back, around the navel). Blood tests and X-rays are useful to confirm the diagnosis. If big joints (eg. the knee joint) are swollen, your doctor may aspirate the fluid with a needle and send it for special examination. This will help the doctor to differentiate between infective, degenerative or inflammatory joint disease.

Nevertheless, there are various good drug treatments that can reduce joint swelling and pain, slow down joint damage and preserve function. Some drugs can control both skin and joint disease. Most patients have their disease under control and lead meaningful lives.

NSAID (non-steroidal anti-inflammatory drugs) like diclofenac acid or COX-2 inhibitors are helpful to reduce pain and stiffness. Reducing pain is important as it makes you more comfortable. However, these drugs will

only reduce the symptoms and do not slow down the progression of the disorder.

DMARDs (disease modifying anti-rheumatic drugs) are often prescribed. They reduce swelling and inflammation and slow down joint damage. These include methotrexate, sulphasalazine, leflunomide and cyclosporine. Low dose steroids may be used. Steroids can also be injected directly to a joint to relief pain and swelling. However, steroids should not be used in the long term because of significant side-effects. Stopping steroids suddenly may also trigger a flare in psoriasis skin lesions. Your doctor is the best judge on which drugs to use.

There is now a group of drugs call biological DMARDs, which can control the disease quickly and greatly slow down joint damage. They are given as injections and are expensive. Not all PsA patients are suitable or need such drugs. Your doctor is the best judge on which drugs to use.

While some sports may stress the joints excessively and are not suitable, most gentle exercises like jogging, walking, swimming are good to keep you strong. It is important not to exercise the acutely swollen and painful joints. Your physiotherapist is the best person to ask for advice.

PsA is not only a disorder of the joint and skin. The inflammation can affect many organs. Therefore untreated or under-treated PsA can result in anemia, fatigue and weight loss. PsA patients are more prone to obesity, high cholesterol, heart attacks and strokes. It is important to get appropriate treatment, maintain a healthy diet and regular exercises.

All information above is also available in Mandarin. Here's a copy for reference:
银屑病关节炎.pdf