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Managing psoriasis in primary care

Psoriasis is a chronic, highly prevalent disease of the skin which can also affect the joints, with males and females being equally affected. It can present at any age but is rare in those under the age of 10 years. It is most likely to appear around the age of 30, however there is evidence that it may first appear in the eighth or ninth decade.1

There is also a genetic predisposition in psoriasis together with ethnic variations. It is common in Caucasian population, with the highest incidence reported in Northern Europeans; it is less common in Asian people and is seldom seen in American Indians, Africans or Eskimos.2

The pathogenesis of the disease is complex and a knowledge of this is important to understand the way treatments work. Psoriasis is characterised by bright red, elevated, scaly plaques which mirror the pathophysiological events that occur in the skin.

There is an increase in the number of proliferating keratinocytes in the basal layer of the epidermis, which together with the loss of differentiation, is responsible for parakeratosis which reflects the clinical presentation of lesions of erythematous plaques with thick silvery scales. Capillary dilatation is also present which gives a vascular dermal response, ie. redness of the skin, in active lesions.3 The growth rate of the psoriatic epidermis is up to 10 times that of normal epidermis.

From the website of Under the Spotlight, in association with The International Federation of Psoriasis Associations (IFPA), is a very simple and easily understood explanation for patients of the cell process in this disease:

“Under normal circumstances the skin renews itself every 28 to 30 days. In psoriasis, faulty signals in the immune system accelerate this process causing new skin cells to form in 3 to 5 days. The body does not shed these immature skin cells, so they build up on the surface to form plaques.”4

Psoriasis exists in a variety of clinical types and distribution and tends to run a variable course which makes it difficult to give a prognosis. Disease activity will determine the prognosis in that the more active the disease is, the poorer the prognosis.1

It is recognised that there are important environmental triggers in psoriasis including infection (particularly streptococcal infection), drugs such as anti-malarials, lithium, systemic corticosteroids, and physical and psychosocial stress.

It is essential to document an accurate medical history, family history, precipitating factors, drug history and quality of life assessment at the initial consultation. The practitioner should be aware that there can be a significant impact on psychosocial and psychological aspect of the patient's life. It should not be assumed that there is a direct correlation between the severity of the disease.5

Psoriasis is also associated with a specific form of arthropathy, therefore if there is history of joint pains or stiffness, regardless of severity of psoriasis, early referral to rheumatologist for evaluation is essential.

Studies show a significant and growing link between psoriasis and other chronic conditions.6

Diagnosing psoriasis is often fairly straightforward with distinctive clinical appearance, but it must be considered that there are other skin conditions that may be confused with psoriasis.

The most common form is plaque psoriasis which accounts for approximately 85% of all cases and presents as well circumscribed oval or coin shaped plaques with scale of varying thickness present. The distribution of lesions in most cases is highly symmetrical and may be localised such as on scalp which often extends to forehead, temples, nape of neck and sacral area, involving the natal cleft and genitalia. It also presents as extensive chronic plaque psoriasis.

Other forms include guttate psoriasis which presents as many small lesions, usually 2 to 10mm in diameter, with a 'raindrop' appearance, and often follow a streptococcal throat infection in younger patients. Guttate lesions predominantly appear on the trunk with a rapid onset and usually clear over a period of a few weeks. Emollients, mild topical steroids or ultra violet (UV) light therapy may be prescribed.

Flexural or inverse psoriasis is commonly seen in obese patients affecting normal body fold such as under the breasts, natal cleft, inguinal area and axillae. This presents as red, shiny, well-demarcated plaques with no silvery scales present. Mild to moderate topical steroids or combination of steroid withantifungal/antibiotic such as Trimovate cream may be indicated.

Nail involvement can take several forms, from subtle to disfiguring changes. Characteristic changes are pitting, longitudinal striations, onycholysis, discolouration or subungual hyperkeratosis. Referral to dermatologist may be indicated as there is little in the way of topical therapy for nail psoriasis.

In palmoplantar psoriasis, the palms of the hands and soles of the feet may be the only presentation of psoriasis, with thick scaling and often pustules present. This tends to be debilitating and more recalcitrant to treatment, necessitating the use of potent steroids and occlusive paste dressings.

The scalp is affected in approximately 50% of patients and is often intractable and is difficult to manage for the individual. Topical application, after removal of scale, should be demonstrated to optimise treatment therapy, emphasising that it is the scalp and not the hair that is being treated.

Tar shampoos to inhibit the proliferation of scale and topical steroids, in the form of scalp lotions to reduce inflammation and itch, are frequently used.
Keobner phenomenon is a classic feature of psoriasis of unknown aetiology, where an area of skin which has been traumatised or injured can form psoriatic lesions.

In scalp psoriasis this may be the reason that the area is difficult to treat due to the over-zealous washing, scratching and picking of psoriatic lesions causing further plaques to appear.

More serious forms of psoriasis requiring hospital admission are erythrodermic psoriasis, affecting much of the skin as a result of confluence of chronic plaque psoriasis, or unstable psoriasis which may be drug-induced or following infection or discontinuing steroid therapy. Generalised pustular psoriasis is a rare form in which the skin is inflamed and punctuated with pustules often merging to form sheets of affected skin.

Classification of psoriasis is clinically defined as mild if less than 10% of body surface area is affected by plaque, moderate if 10 to 15% of body surface is affected, and severe if more than 15% of body surface is affected. 

The severity of the disease determines the type of treatment prescribed. Mild to moderate psoriasis can be treated in primary care, with increasing severity of the disease requiring dermatological referral for systemic therapies, biological therapy or for UV light therapy with or without psoralens.

Treatments
Topical therapies are used to treat mild and mild-to-moderate psoriasis.

In prescribing topical treatments one must ensure patients are allowed to make an informed choice of topical treatments, taking into account time factors, family life and occupation.  

The role of the nurse is pivotal in supporting the individual with a chronic skin condition. Helping patients to understand the disease process, discuss treatment options, setting realistic expectations and empowering the individual to take ownership of their own skin condition is of paramount importance.

There is evidence of better use of topical therapies and reduced severity of skin conditions associated with nurse-led care. Extra time taken in educating the patient8 and the fact that the rationale for adherence to topical therapies is better understood by the patient ensures improved outcome in disease management.9

Conclusion
Key points in supporting and managing psoriasis in the
community are:
    - Strengthen links between dermatology colleagues through educational opportunities.
    - Educate and support patients and carers.
    - Individualise treatment plans.
    - Demonstrate application of topical treatments.
    - Ensure a life-line of access via telephone for patient to nurse contact.
    - Review patients timeously to ensure treatment is effective.
    - Acknowledge that each patient will have different needs and timelines.

References
1.         Fry L. An Atlas of Psoriasis - Second Edition. London: Taylor & Francis; 2004.
2.         Camisa C. The Clinical Variants of Psoriasis. In: Handbook of Psoriasis. Malden: Blackwell Publishing; 2004.
3.         Mentor A, et al. Guides to Clinical Practice: Psoriasis - Second Edition. London: Heath Press; 2004.
4.         Under the Spotlight. Available at: www.underthespotlight.ie/psoriasis.html
5.         Penzer R, Ersser S. Principles of Skin Care: A Guide for Nurses and other Health Care Professionals. Oxford: Wiley Blackwell; 2010.
6.         National Psoriasis Foundation. Comorbid Conditions Issue Brief. January 2011. Available at: www.psoriasis.org/document.doc?id=793
7.         Gradwell C et al. A randomised control trial of nurse follow-up clinics: do they help patients and do they free up consultants' time? Br J Dermatol 2002;147:513-7.
8.         Bewley A, Page B. Maximising patient adherence for optimal outcomes in psoriasis. J Eur Acad Dermatol Venereol 2011;25(Suppl 4):9-14.

Resources

British Association of Dermatologists
www.bad.org

SIGN Guidelines 121 - Diagnosis and management of psoriasis and
psoriatic arthritis in adults  
www.sign.ac.uk/guidelines/fulltext/121/contents/html

Psoriasis Association
www.psoriasis-association.org.uk

New Zealand Dermatological Society Inc. (for clinical images of
psoriasis)
www.dermnetnz.org