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Chronic plaque psoriasis: an update

Karina Jackson
RGN BA(Hons) MSc
Nurse Consultant Dermatology
St John's Institute of Dermatology

Psoriasis is a chronic, inflammatory, noninfectious skin disease with an estimated prevalence of 1-2% in UK.(1) It affects male and females equally and can occur at any age; however, the peak age of onset (type 1) falls between 14 and 21 years of age, and 55-60 for late onset (type 2) psoriasis. It is a chronic skin disease with no cure. Treatment is based on controlling the signs and symptoms, and optimising quality of life. There are no definitive diagnostic tests for psoriasis and diagnosis is made on clinical examination and history alone.

What are the clinical features of psoriasis? 
The predominant clinical features of psoriasis are erythema (redness), induration (thickening) and desquamation (scaling), usually in the form of an oval-shaped plaque. These features will vary depending on the body site affected and the type of psoriasis. Plaques can vary in size from 2 mm diameter to confluent plaques covering an entire body area. Common and classical sites affected are extensor aspects such as elbows and knees, the scalp and lumbosacral region. Scalp, nails, face, ears, genitalia and flexures can also be concurrently affected. Chronic plaque psoriasis accounts for 85-90% of cases of psoriasis. Other less common forms of psoriasis are guttate (raindrop lesions), palmar-plantar pustulosis (palms and soles), generalised pustular and erythrodermic psoriasis.

What causes psoriasis?
The exact cause of psoriasis is unknown; however, there is thought to be a genetic predisposition. A Scandinavian study predicted the risk of developing psoriasis to be as high as 28% if one parent has psoriasis, and 65% if both parents have psoriasis.(2)
This genetic predisposition combined with an external trigger may result in psoriasis. In addition, certain trigger factors are commonly seen: streptococcal upper respiratory tract infection in guttate psoriasis; stress (both physical and psychological); drugs including ß-blockers, antimalarial drugs, nonsteroidal anti-inflammatory drugs and lithium; the withdrawal of glucocorticosteroids; and high alcohol consumption.
Are there any complications?  
Psoriasis can have a significant psychological impact on the individual, which could result in low self-esteem, distorted self-perception, depression and anxiety. It can affect normal interpersonal relationships with family, friends and new social contacts. Living with psoriasis can be an isolating experience for the patient.
There is an increased risk of cardiovascular disease, diabetes and other autoimmune diseases, such as rheumatoid arthritis and Crohn's disease in psoriasis.(3,4)

What is the current best treatment?  
Treatment choice is based on the severity of the disease, the impact on quality of life and the distribution of the psoriatic lesions (see Table 1). About 75% of patients with chronic plaque psoriasis can be satisfactorily treated in a primary care setting with topical (firstline) therapy alone.(2) There are a range of creams, ointments, pastes, oils and lotions available for the topical treatment of psoriasis. Treatments should be applied once to twice daily. Significant improvement will take up to 12 weeks to achieve using most topical therapies, and it is important that patients are aware that it may take this long.

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Emollients
Emollients help moisturise dry skin, ease itching, reduce scale, soften fissured areas and enhance the penetration of other topical treatments. They should be used when bathing or washing as a soap substitute.
Very mild psoriasis may respond to treatment with emollients alone.

Antipsoriasis treatments
There are a number of different antipsoriasis treatments available, all will suppress the psoriasis. The choice of treatment will be influenced by factors identified in the assessment. Some treatments are best kept in reserve for specialist supervised application only, such as nonproprietary dithranol and crude coal tar. Some treatments come in scalp applications to treat scalp psoriasis.

Managing scalp psoriasis
Scalp psoriasis can be very distressing for patients as it is so visible. The treatment goals are to moisturise the scalp, remove excess scale and treat inflammation.  Very mild, flaky scalp psoriasis can be treated with medicinal shampoo alone. Tar shampoos are recommended. The patient should wet their hair, massage the shampoo into the hair and scalp and leave it for 10 minutes before rinsing out. This should be performed at least three times a week. The dryness can also be aided with the use of a simple emollient (oil or lotion) massaged into the affected area.

Specialist treatment
For patients with moderate-to-severe psoriasis second-line therapy may be required via a specialist. This can include phototherapy, photochemotherapy or systemic drug treatment. This may be further supported by a period of inpatient or daycare treatment at the hospital.

The role of the practice nurse
Seventy-five percent of patients with psoriasis can be adequately treated by primary care healthcare practitioners using topical therapy alone. Nurses play a key role in patient support, education and review.
Managing the condition effectively requires a good deal of information giving, empathy and support. This can include patient education, teaching and demonstration of treatment application techniques, discussing lifestyle issues, providing psychological support and referrals for other support (eg, chiropody). It is important that patients with psoriasis have an understanding that the disease is a chronic relapsing condition, and the main aim of treatment is the suppression of signs and symptoms - not to cure. Patients need to have realistic expectations of the treatment outcome. This means explaining that the treatment will be lengthy, that it is not curative and the psoriasis is likely to relapse if they stop therapy too soon. In addition, time should be spent talking about what the treatment is designed to achieve, how, where and for how long to use the therapy, and any local side-effects to expect, such as stinging, burning, irritation and staining. Giving all this information can be time consuming. However, this time investment is well spent as it will lead to better understanding and a greater likelihood of the patient adhering to the treatment plan.
Using written materials to support the information giving can be helpful. Patient support groups, such as the Psoriasis Association, have a series of helpful
leaflets for use in clinics.
Referral to a specialist service should be considered according to the criteria detailed in Box 1.

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Conclusion
Psoriasis is a chronic skin condition that can have a considerable impact on quality of life. The management of the disease requires good nursing support in both primary and secondary care. The provision of time and focused health education is a key role for the nurse in psoriasis management.

References

  1. Griffiths CEM, Clark CM, Chalmers RJG, Li Wan Po A, Williams HC. A systematic review of treatments for severe psoriasis. Health Technol Assess 2000;4:1-125.
  2. Swanbeck G, Inerot A, Martinsson T, et al. Genetic counselling in psoriasis: empirical data on psoriasis among first-degree relatives of 3095 psoriatic probands. Br J Dermatol 1997; 137:939-42.
  3. British Association of Dermatologists and Primary Care Dermatology Society. Psoriasis guideline. Available from: http://www.pcds.org.uk
  4. Yates VM, Watkinson G, Kelman A. Further evidence for an association between psoriasis, Crohn's disease and ulcerative colitis. Br J Dermatol 1982;106:323-30.

Resources
Recommended further reading
Hughes E, Van Onselen J, editors. Dermatology nursing: a practical guide. London: Churchill Livingstone; 2001.
Smith C, Barker J, Menter A. Fast facts - psoriasis. Oxford: Health Press Limited; 2002.
Recommended books for patients
Lewis J. The Psoriasis handbook: a definitive guide to the causes, symptoms and all the latest treatments. London: Vermilion; 1996.
Dave VK. Skin care for psoriasis. London: Class Publishing; 1997.

Support groups/Professional organisations
The Psoriasis Association
7 Milton Street
Northampton NN2 7JG
W: www.psoriasis-association.org.uk
Psoriatic Arthropathy Alliance
PO Box 111
St Albans
Herts AL2 3JQ
W: www.paalliance.org
Primary Care Dermatology Society
Gable House
40 High Street
Rickmansworth
Hertfordshire WD3 1ER
W: www.pcds.org.uk
British Dermatological Nursing Group
4 Fitzroy Square
London W1T 5HQ
W: www.bdng.org.uk