Incidence
Moderate or severely affected psoriasis sufferers make up approximately 1% of all individuals.  It is more common in for adults to be severely effected than what it is in children. When effected at an early age, children tend to become sufferers of ongoing severe psoriasis in adulthood.

Causes
Medical science still does not understand why many individuals experience severe psoriasis while others don't.

Signs and Symptoms
Extensive disease affecting more than 20% of the body surface area is usually clinically apparent and easily visible. There may be significant shedding of dead skin cells from the surface of the skin which can be socially embarrassing.

Some individuals may also experience arthritis which can resemble rheumatoid arthritis. The joints become stiff after resting, especially after a nights sleep. There may be inflammation of the muscles and tendons around the elbows, wrists and heels. Joints may lose their range of movement and become deformed or locked.

Complications of the Disorder
If the skin becomes totally reddened (erythroderma) then there can be problems with body temperature control, fluid loss, heart failure and loss of protein and iron from the surface of the skin. Potentially this can be a life threatening situation.

If severe widespread sterile pustules develop (pustular psoriasis) then again this potentially can be life threatening.

The main complication is the social embarrassment associated with any visible skin disease.

Tests
There are no specific tests which help to identify moderate or severe psoriasis apart from clinical examination. Tests may be indicated to monitor certain drug treatments which are required to control severer disease.

Treatment

Phototherapy
Most phototherapy use for treating psoriasis has centred around PUVA treatment which is a combination treatment using Psoralens (P) and ultraviolet A light (UVA). However in recent years treatments based on narrow band (UVB) have been found to be almost as effective as PUVA treatment without the need for drug treatment.

PUVA
Psoralens is a naturally occurring chemical found in many plants which when taken by mouth increases the sensitivity of the skin to UVA. The usual form is as a tablet containing 8-methoxypsoralens (8 MOP) in a capsule form. This is taken 1 or 2 hours before ultraviolet exposure. Some people develop nausea with this and the dosage may have to be adjusted.

UVA represents the longer wavelengths of ultraviolet light. UVA is similar to sun bed wavelengths and higher levels of UVA are available from special machines compared to the amount of low background UVA that is available from the suns rays.

The combination of psoralens and UVA helps to slow down the rate of cell division in the skin affected with psoriasis. PUVA machines are usually available in dermatology hospital departments. They are large boxes similar to shower cabinets where an individual has to stand exposed to the ultraviolet light for a determined period of time. Treatment may be required 2 or 3 times a week over a minimum period of 2 months.

Bath PUVA involves immersing in a bath containing psoralens prior to exposure to ultraviolet light. This appears to give equally effective results although it does require a longer period of attendance at hospital prior to ultraviolet light exposure. This can be of benefit for patients who feel nauseous with psoralens taken by mouth. In addition it is recommended that when patients take psoralens by mouth that Polaroid type sunglasses are worn for 24 hours afterwards to help prevent potential cataract development.

Narrow band UVB involves again standing inside an appropriate cabinet for a predetermined period of time. No drug therapy however is required in association with this.

The main concern with phototherapy is the potential of ultraviolet light to damage the skin in the long term and therefore this treatment is used for limited courses rather than as an ongoing treatment for persistent disease. PUVA treatment has now been available for almost 30 years and skin cancer risks are increased if ultraviolet light exposure has been significant. Psoralens as a drug appears to be well tolerated and relatively safe. Effects on pregnancy are unknown and therefore efficient contraception should be ensured by females of child-bearing potential.

Neotigason (Acetretin)
Neotigason belongs to a group of drugs known as retinoids which are derivatives of vitamin A. This is either taken alone or combined with local treatment as for mild psoriasis or combined with ultraviolet light treatment. It helps by slowing down the rapidly dividing skin cells in the surface of the skin (epidermis). However the drug can remain within the body for up to 2 years and is potentially damaging to any unborn foetus. Pregnancy is therefore contraindicated not only whilst on therapy but for 2 years post therapy.

Side effects with Neotigason are common. Dryness of the lips, eyes, face and occasional nose bleeds are commonly experienced but usually relieved by moisturizers and lip salves.

Hair loss may occur in some individuals which is reversible on discontinuation of treatment.

Muscle aches and pains relieved by avoiding vigorous exercise and by anti-inflammatories such as paracetamol may be encountered. Headaches usually relieved by paracetamol can occur and may not settle until therapy is discontinued.

Ongoing treatment with Neotigason may affect the levels of fats in the blood and a regular check is required on this. If long term treatment is required changes on the bones close to the joints may occur and therefore X-rays may be required every couple of years.

Methotrexate
Methotrexate is not only used for treating cancer but can be helpful for psoriasis. Again this helps to slow down the rate of cell turnover.

Methotrexate is usually taken by mouth as a single weekly dose. Although Methotrexate has been used in the treatment of severe psoriasis for more than 30 years it can have some adverse side effects. It can cause anaemia, increasing the risk to infections and can cause excessive bleeding and bruising. Therefore when taking Methotrexate regular blood tests are required at the start of treatment (i.e. weekly) and less often as time goes on (perhaps every 2 to 3 months). Methotrexate can also damage the liver but usually only after many years of continuous treatment. It may therefore be necessary to monitor the liver with regular blood tests, ultrasounds or liver biopsies. The risk of damaging the liver is greatly increased by alcohol and therefore alcohol consumption whilst on Methotrexate should be discouraged. Methotrexate affects the male and female sexual reproductive organs and therefore you should not become pregnant or father a child whilst on Methotrexate.

Cyclosporin
Cyclosporin has been extensively used in transplant patients for many years and recently has become available for treating severe psoriasis. It may take 3 or 4 weeks before any benefit is seen. It can significantly reduce the inflammation seen in patients with psoriasis and subsequently reduces scaling.

It is either taken in the form of capsules or as a solution by mouth. The most common side effect is nausea and indigestion. These can usually be treated without stopping the Cyclosporin. Cyclosporin can however damage kidneys and cause high blood pressure. Therefore monitoring of kidney function with blood tests and urine collections are required, as well as regular monitoring of blood pressure.

Hydroxyurea
Hydroxyurea slows down rapidly dividing skin cells. It generally takes at least 8 weeks for clearance of psoriasis to be achieved.

Although Hydroxyurea has been used in the treatment of psoriasis for more than 30 years again it can occasionally have adverse side effects. It can make patients anaemic, prone to infections and cause excessive bleeding. For this reason whilst you are having Hydroxyurea you will require regular blood checks, initially weekly and then less often perhaps every 2 months once under control. Adequate contraception is essential whilst on Hydroxyurea and for 2 months after discontinuing treatment. You must not father a child for the time of the treatment period. If there has been no response within 6 weeks alternative treatments may have to be considered. Most people requiring Hydroxyurea require at least 6 months of treatment before deciding to stop treatment.

Rotational Therapy
Most patients with severe psoriasis will be helped by at least one of the above treatments. Your doctor may, from time to time, stop treatment or change the treatment to better control the disease and minimize the potential long term side effects.

A period of in-patient treatment with bed rest may occasionally be required for severe psoriasis, particularly if it involves total body skin (erythroderma) or if there is extensive pustular involvement which may be life threatening

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