What is Psoriatic Arthritis?
Like Rheumatoid Arthritis, Psoriatic Arthritis is also an inflammatory arthritis. However, it tends to affect the body in a different way and in a different pattern to rheumatoid arthritis. Psoriatic arthritis is an arthritis that usually affects joints in an asymmetrical way, and tends to affect fewer joints at one time then Rheumatoid Arthritis. Unlike Rheumatoid arthritis, it can also affect the spine.
Psoriatic arthritis is an inflammatory arthritis that occurs in association with a rash called 'psoriasis', hence the name 'psoriatic' arthritis.
Who gets Psoriatic Arthritis?
Psoriatic arthritis usually affects people who have the rash psoriasis. It is thought that 20-30% of people with psoriasis get arthritis in association with it.
More men than women get psoriatic arthritis, and it affects adults of all ages.
It is ten times less common then Rheumatoid Arthritis, affecting 0.1% of the population.
What are the symptoms of Psoriatic Arthritis?
Each person has a unique presentation of Psoriatic Arthritis and the symptoms may change as life goes on and the disease progresses.
Typically Psoriatic Arthritis affects the joints at the end of the fingers. These are called 'The Distal Inter Phalangeal Joints (DIPJs for short). In association with that the nails and the nail beds are often involved causing ridging, pitting and breaking away of the nails (known medically as onycholyisis)
Psoriatic Arthritis can also affect the large joints of the body such as the knees, wrists and shoulders as well as the spine.
In the beginning, Psoriatic Arthritis usually affects a few joints at one time, but as the disease becomes advanced more joints can be affected and it can become quite symmetrical.
Tendons can also be involved in Psoriatic Arthritis, becoming inflamed and sore, and in some people this can be the biggest part of their disease. The Achilles Tendon is one which is quite commonly affected, causing pain, stiffness and difficulty walking and moving.
Sometimes with Psoriatic Arthritis whole digits such as fingers and toes can become inflamed. They can look like sausages when this happens, and are referred to as 'sausage digits' or in medical terms 'dactylitis'.
People with Psoriatic Arthritis tend to be quite stiff in the affected joints, can have pain in affected joints and can feel generally unwell tired and aching as well.
How do we diagnose Psoriatic Arthritis?
Psoriatic Arthritis is a diagnosis that is usually made clinically, that means with the experience of the Rheumatologist. Sometimes it is very clear that the arthritis is Psoriatic when there are things such as nail changes, dactylitis and the involvement of the distal interphalangeal joints. However, when there is no psoriasis and the symptoms are not typical, particularly in the early stages of the disease it can be very difficult to diagnose.
The things that make a diagnosis more clear are:
Distal Interphalageal Joint involvement
Achilles tendonitis or other tendon involvement
However, as with all things in life, things are not always clear and sometimes things become more clear as a disease gets more established.
Its interesting to note that 25% of people with Psoriatic Arthritis do NOT have Psoriasis at the time of the diagnosis!!
To investigate causes of arthritis, your Rheumatologist will order many blood tests as well as xrays, and possibly ultrasounds of affected joints.
How do we treat Psoriatic Arthritis?
Treatment of Psoriatic Arthritis depends on how severe the arthritis is, and where it is affecting your body. In this regard, treatment is very much tailored to each person and it is important to work with you Rheumatologist in this regard.
If the arthritis is very mild, perhaps affecting only one or 2 digits (eg finger or toe) anti inflammatories may be all that is required. However, if more parts of the body are involved and symptoms are more severe DMARDs such as Methotrexate and Sulfasalazine are required to prevent further damage to the joints, and to provide a better quality of life for you.
Psoriatic Arthritis is less likely to respond to prednisolone than Rheumatoid Arthritis, which is an interesting feature of the disease suggesting a unique chemical pathway of inflammation! This means that NSAIDs can be used instead. Its important to minimise how often these are taken as they are associated with a lot of serious side effects in the long term.
If only a few joints are affected, sometimes cortisone injections into those affected joints can help to control the disease.
If the disease is very severe and doesn't respond to DMARD therapy such as Methotrexate or Sulfasalazine, Biological drugs can be used.
Common ones used in Psoriatic Arthritis are Etanercept and Adalimumab.
Similar to Rheumatoid arthritis, not everyone is eligible for these drugs under government subsidy so it is important to discuss this with your Rheumatologist.
Drugs are not a cure for Psoriatic Arthritis, but they can be very effective in controlling symptoms and thus improving quality of life.
What is the long term outcome for Psoriatic Arthritis?
The course of this arthritis is different for each person. Many people have mild disease, affecting only a few joints, and others have more severe and generalised disease.
In this day and age we have many drugs which can support people with the disease thus improving the chances of a good outcome. The drugs are not a cure, but they can help to control symptoms and thus reduce the risk of damage to joints, and improve quality of life by reducing daily symptoms.
Long term anti inflammatories are not the best solution for ongoing symptoms if taken daily due to the high possibility of severe side effects and it is far better to be on a DMARD if there are significant ongoing daily symptoms.
Speak to your Rheumatologist to tailor the treatment program that is right for you.