Psoriasis: understanding and management

Psoriasis can present with a wide range of symptoms, and can affect not only the skin but also other tissues and organs, as well as having a profoundly negative effect on quality of life

The skin is the largest organ of the human body, and according to the British Skin Foundation, 60% of people in the UK currently have a skin condition or have previously had a skin condition.¹ With a UK population of 67 million, that is around 40 million people.² Of course, a large proportion of those cases will be very mild and self-resolving, but some people will be worried about any change to their skin. The campaigns around skin cancer will no doubt heighten concerns, but there are more than 3,000 skin conditions.³ Diagnosing and managing each presenting rash can pose problems, even for common conditions such as psoriasis.

Psoriasis is an auto-immune, inflammatory condition. It often starts or becomes more obvious in or around puberty, but younger children can get psoriasis, as can adults in later life. Both men and woman are affected equally.⁴

Psoriasis is a chronic disease that for many is mild and manageable with basic over the counter (OTC) medicine. For more severe cases, such as those who have chronic plaque type disease and who may also develop psoriatic arthritis, the impact can be devastating, life-changing and can lead to a lifetime of care, treatment and sometimes frequent inpatient hospital stays.

PRESENTATION

There are several different types of psoriasis, including psoriatic arthritis (PsA). The prevalence of PsA, in people who have psoriasis, is estimated at up to 30%.⁵ Psoriasis varies enormously in duration, with periods of flares and remission.

Chronic plaque psoriasis is the most common presentation and is characterised by lesions of red or hyperpigmented, scaly, sharply demarcated, indurated plaques, present on the extensor surfaces (elbows, knees, lower back and scalp).⁴

Rashes can appear differently on different skin tones. For example, a rash on darker skin may look like a series of grey or white spots, while many medical textbooks describe it as erythematous (red). It is crucial for medical professionals to understand how health issues can present on the full range of skin tones.

People with psoriasis will present with a number of symptoms, such as dry skin, flaking skin, white/silvery scaling, distinct plaques (discs of red, scaling skin of varying sizes), thickened, raised areas (hyperkeratosis), itchy skin, redness (which may be dark red/purple/hyper-pigmented (darker) in skin of colour), sore/tender skin, fissures (cracks in skin), nail pitting, nail changes and lifting of the finger and toe nails from the bed (onycholysis).

Psoriasis is associated with systemic manifestations in many organ systems, in which both genetic and environmental influences have a critical role. There is strong evidence of an association between psoriasis and cardiovascular disease, particularly in severe disease.

It starts to become clear that with such a variety of symptoms, a detailed knowledge is needed to understand what is likely to support a diagnosis of psoriasis and to determine appropriate treatment quickly. The rapid turnover of psoriatic skin of 4-7 days as opposed to the normal 28-day cycle, makes that decision even more critical, as it could prevent months of misery once the skin plaques become widespread.

PREVALENCE AND DISTRIBUTION

Skin psoriasis affects around 1 in 50 people, about 1.3 million, or around 2% of the UK population.⁴

Nail changes, including pitting and ridging, are present in nearly half (40%-50%) of all those who have psoriasis.⁴

There are varying estimates of the prevalence of PsA. It is generally accepted that around 1 in 3 or 4 (up to 30%) of those that have psoriasis may develop PsA. This works out at about 325,000 people, or around 0.5% of the UK population.⁵

In approximately 80% of cases, the arthritis will develop after the appearance of psoriasis. However, in about 20% of cases, the joint inflammation will come first.⁴

The age of onset for PsA is later than skin disease, peaking in the 40s.⁴

Estimates for onset of psoriasis/psoriatic arthritis

• 70% (the majority) have psoriasis before the onset of psoriatic arthritis⁴
• 20% of patients develop psoriatic arthritis before any skin changes occur⁴
• 10% of patients develop skin psoriasis and arthritis at the same time⁴

Psoriatic arthritis is more common in people with type-1 early onset psoriasis (chronic plaque psoriasis). Nail disease is more frequent in psoriatic arthritis.⁴

SKIN ASSESSMENT

The busy non-specialist, when confronted with need to diagnose, can follow some simple checks, which involve taking a clinical and family history, and examination of the skin, noting and assessing the areas of the body affected, extent and physical severity of psoriasis.

Visual examination of the skin requires adequate light to observe subtle changes in surface, texture and colour. Ideally, it is best to examine the patient undressed but an examination can also be achieved in primary care by rolling up clothing and examining the body systematically.

The skin assessment should also include skin appendages, the nails and the scalp. These areas of the body are very important in a psoriasis assessment. Remember that 50% of people with chronic plaque psoriasis will have scalp involvement. Nail changes, such as nail pitting, ridges, grooves and separation of the nail plate from the bed are common features. Any systemic upset, malaise or fever should also be noted, as this may indicate unstable psoriasis.⁶

The standard internationally recognised scoring system for psoriasis is the Psoriasis Area Severity Index (PASI),⁷ a scoring system that is generally used in secondary care and research settings to record current severity and then used to monitor improvements following treatment course. A PASI score can range from 0 to 72, although 72 is the highest possible option, it’s more likely that most people will be in the following ranges:

• 0 to 5: none to mild psoriasis
• 6 to 10: moderate psoriasis
• 11 or above: severe psoriasis
• Scores over 40 are considered rare.

In a primary care setting the PASI system may be difficult to use as the calculation takes time and is across a number of domains to arrive at the final score. However, understanding PASI scores is important as they are used to describe improvement from baseline: scores are presented as PASI50 (50% improvement) PASI75 (75% improvement) and PASI90 (90% improvement). PASI100 equals clearance with no signs or symptoms visible.

PASI scores are also used to determine eligibility for advanced biologic and biosimilar therapies recommended by NICE, but which have restrictions on access.⁶

PROGNOSIS AND IMPACT

The course of the disease and prognosis can vary, but most likely, once an individual develops psoriasis, they will have it for their whole life. This could be very mild and intermittent, but some patients may never see clearance. When first diagnosing psoriasis, it is key to provide a balanced view of the prognosis, without providing unrealistic outcomes. Psoriasis can be managed effectively and, in some cases, it may go into remission for many years.⁴

The early exchange between healthcare provider and patient can have a lasting impact and influence the psychological implications of the condition. Having a very visual condition that although common, is not generally understood by the wider population, can be very distressing. In qualitative survey data submitted to NICE, the charity PAPAA⁸ suggests that many people are reluctant to expose their skin in public, either through fear of the reactions of others or because they have been abused or mocked in the past. For healthcare providers understanding the huge impact that psoriasis can have, even after clearance due to fear of return, is vital in the management of the condition.

The impact of psoriasis on quality of life can be considerable and should be considered when assessing patient’s needs and their response to treatment.

The Dermatology Life Quality Index (DLQI) is a simple, self-administered, and user-friendly validated questionnaire used to measure the health-related quality of life of adult patients (over 16 years) suffering from a skin disease.⁹ The scoring considers more than just treatment outcomes, but records symptoms and feelings, daily activities, leisure, work or school, personal relationships, and treatment side effects. It is available at https://www.pasitraining.com/dlqi.html.

TREATMENTS AND MANAGEMENT

Treatments fall into three categories, topical creams and ointments applied to the skin, phototherapy when skin is exposed to certain types of ultraviolet light and systemic drugs, delivered as an oral or injected medication that works throughout the entire body.¹⁰

For primary care prescribing the most likely first line therapy will be a topical preparation. These offer a number of benefits, can be applied easily to most areas of the body. Some assistance might be needed for hard-to-reach areas or when mobility and dexterity are hampered, such as in those with psoriatic arthritis.

Emollient or aqueous creams are useful for most skin conditions, particularly where the skin is dry and flaky. These come in a variety of forms, including those that can be added to the bath. Although they provide some symptom relief, they are not likely to change the course of psoriasis. Active products that either act directly on the inflammatory process or slow down skin over-production are the main stay for mild to moderate psoriasis.¹¹

Products containing mild to potent steroids, such as betamethasone or clobetasone, can provide short-term relief. Very potent corticosteroids should be restricted to no more than 4 weeks' use.⁶ Adverse events such as thinning of skin (striae) remain a problem with these products. Other issues associated with long-term overuse include cushingoid changes and adrenal suppression.¹¹

Vitamin D or a vitamin D analogue, such as calcipotriol, calcitriol and tacalcitol offer a long-term alternative to the use of topical steroids, although a combination of calcipotriol/betamethasone is available for stable plaque psoriasis, where less than 30% of the body is likely to need treating.¹²

NICE recommends offering a potent corticosteroid applied once daily plus vitamin D or a vitamin D analogue applied once daily (applied separately, one in the morning and the other in the evening) for up to 4 weeks as initial treatment for adults with trunk or limb psoriasis.⁶

For many years the mainstay of therapy included coal tar preparations applied once or twice daily. The strong smell of tar often made people reluctant to use these products, but coal tar still acts as an alternate for some. Salicylic acid is another product that has lost favour with people who have psoriasis, as staining and skin irritation has been associated with its use.

For those who wish to self-manage their psoriasis, quick access to treatment and advice is a vital part of management, particularly when the condition flares. Getting access to supplies of topical therapy can be very useful in controlling an early flare.

REFERRAL

GPs and general practice nurses are well equipped to support patients with mild to moderate plaque psoriasis in the primary care setting, particularly if they have a full understanding of the issues and needs of patients. But there are always going to be cases that are not resolving with the therapies available in primary care. Knowing when to refer is, of course, a matter of professional judgement and when there is benefit to be gained. This could be to establish a diagnosis, provide access to therapies such as phototherapy or systemic therapies. If psoriatic arthritis is suspected, prompt referral is needed, as delay may lead to joint damage and permanent disability.

NICE recommends referral when there is diagnostic uncertainty or any type of psoriasis is severe or extensive, or any of the following are present:6

• If more than 10% of the body surface area is affected
• When any type of psoriasis cannot be controlled with topical therapy
• Where acute guttate psoriasis* requires phototherapy
• Where nail disease has a major functional, cosmetic impact
• When any type of psoriasis is having a major impact on a person's physical, psychological or social wellbeing.

*Guttate psoriasis is so-called because of the widespread distribution over the torso, back and limbs of a rash of droplet shaped spots. If treated promptly it can resolve within weeks or months, but finding the right treatment for each individual can be challenging and requires specialist input.

People with generalised pustular psoriasis or erythroderma should be referred immediately for same-day specialist assessment and treatment. Refer children and young people with any type of psoriasis to a specialist at presentation.⁶

In conclusion

When presented in primary care with a newly diagnosed individual or someone with refractory psoriatic disease, there are a few simple steps to follow:

• The management of psoriasis can be made easier through two-way discussions with the patient about their needs, including the psychological impact of their condition
• Determine the goals of therapy, and discuss how practical those are for the patient
• Know when extra input is needed, to either establish a care pathway or if the condition has escalated, particularly, if psoriatic arthritis is suspected.

Having a broader knowledge of psoriasis and the confidence to manage it appropriately in a primary care setting will reduce both the physical and psychological impact of the condition.

LEARNING MORE

Understanding of psoriasis has advanced dramatically during the past two decades, although a cure is potentially a long way off. For those with psoriasis there are many resources to help them understand the condition. Patient charities such as the Psoriasis and Psoriatic Arthritis Alliance (PAPAA) can help support and advance the knowledge of both patients and healthcare professionals, with free access to evidence-based information.

In the broad work that primary care is responsible for, gaining that extra knowledge may be difficult. Psoriasis in Practice (PiP) is a practical online distance learning course, that can be accessed via any compatible device computer, mobile and tablet. The course is split into modules, which allows the participant to learn at their own pace and time.¹³

The course is only available to registered healthcare professionals and other suitably accredited individuals. Course includes evidence-based content, the latest NICE and SMC guidance, clinical images, signs and symptoms, the patient’s perspective and personal stories (video interviews) and treatment options. Worth 10-study hours with a certificate available on successful completion (accredited by the RCN Centre for Professional Accreditation).¹³

The charity PAPAA has been funding the development and delivery of the course for 10 years. The programme is completely independent from commercial sponsorship or input, therefore provides a view of psoriasis based on patient need, while recognising the difficulties healthcare professionals face when dealing with this chronic disease at primary care level.¹³

PAPAA is able to provide qualifying NHS staff with free access to the course (subject to availability) for a limited period of time. The usual cost to access the course is £50. To learn more, go to www.papaa.org/pip .

REFERENCES

1. British Skin Foundation. Know your skin. https://knowyourskin.britishskinfoundation.org.uk/about/

2. Office of National Statistics https://www.ons.gov.uk

3. Griffiths C, Bleiker T, Creamer D, et al (Eds). Rook's Dermatology Handbook. Hoboken NJ: Wiley-Blackwell; 2020

4. Griffiths C, Barker J. Pathogenesis and clinical features of psoriasis. Lancet 2007; 370 (9583):263-271

5. Zachariae H, Zachariae R, Blomqvist K, et al. Quality of life and prevalence of arthritis reported by 5,795 members of the Nordic Psoriasis Associations. Data from the Nordic Quality of Life Study. Acta Derm Venereol. 2002;82(2):108-13. doi:

6. NICE CG153. Psoriasis: assessment and management; 2012 (Updated 2017). https://www.nice.org.uk/guidance/cg153

7. PASI Score https://dermnetnz.org/topics/pasi-score

8. The Psoriasis and Psoriatic Arthritis Alliance. The PAPAA Survey 2007- 2022 https://www.papaa.org/get-involved/the-papaa-survey/

9. Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI)--a simple practical measure for routine clinical use. Clin Exp Dermatol. 1994 May;19(3):210-6. doi: 10.1111/j.1365-2230.1994.tb01167.x. PMID: 8033378.

10. NHS psoriasis treatment https://www.nhs.uk/conditions/psoriasis/treatment/ [accessed 11/7/2022]

11. NICE Clinical Knowledge Summaries. Psoriasis emollients (revised May 2021) https://cks.nice.org.uk/topics/psoriasis/prescribing-information/emollients/

12. MIMS. Psoriasis, seborrhea, ichthyosis. https://www.mims.co.uk/drugs/skin/psoriasis-seborrhoea-ichthyosis

13. PAPAA. Psoriasis in Practice version 8; 2022 https://www.papaa.org/shop/psoriasis-in-practice-pip-version-8/