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 PsA, 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 and toes 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 and toes 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 PsA 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. Both PsA and psoriasis have a close tie with obesity, diabetes mellitus, high cholesterol, fatty liver, and heart disease. The inflammation is chronic and can lead to heart disease and strokes.
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. For some patients, the pain and swelling is triggered off by injuries to the bone and joints. 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 and toes 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. If you have psoriasis and are now experiencing joint pain and aches, please seek advice from a rheumatologist. Smoking and obesity may be some of the triggering factors for PsA. Quitting smoking and controlling healthy body weight are always advisable.
PsA can be under good control with long term medication in majority of the patients. A healthy balanced diet and moderate regular exercise are also helpful in preventing complications. 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. 15% of patients reporting having a similar history of arthritis, psoriasis and back inflammation in their family members. 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, while around 30% of them may 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, X-rays, ultrasound or magnetic resonance imaging (MRI) of the joints are useful to confirm the diagnosis. If big joints (e.g. 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.
Although there is no cure for PsA, most patients have their disease under control and lead meaningful lives. Sustained and increasing research is necessary. Specialised and dedicated PsA clinics may result in better outcomes. Some patients may require the care from different specialties including rheumatology, dermatology, gastroenterology and ophthalmology to manage manifestations in bone / joint, skin, inflammation of bowel, and inflammation of eyes.
Currently, 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.