Diagnosing and managing psoriasis in primary care

Psoriasis is a common skin condition occurring worldwide and is often a long-term chronic condition. The problem often follows a relapsing and remitting course with intermittent flare ups when the problem becomes troublesome again after a period of absence of symptoms. It is categorized as a non-communicable disease which is painful, disfiguring and disabling, and for which there is no cure (World Health Organisation (WHO) 2016). There are several different forms of psoriasis, which can make diagnosis difficult. This article therefore will give a brief overview of the condition, its signs and symptoms, treatment, and prognosis, and hopes to give nurses and non-medical prescribers more confidence in recognising and treating this disease.

Types

There are several types of psoriasis, some more common than others. Chronic plaque psoriasis is the commonest type accounting for more than 80% of cases (Yoo, 2023) and can occur as large plaque, small plaque or guttate psoriasis. Although this can occur anywhere on the body, the most frequently affected sites are the extensor surfaces, such as the knees, elbows, and the lower back. Pustular psoriasis (sometimes called palmoplantar pustulosis), can be localised or more generalised is the second most common type and usually affects the palms of the hands and the soles of the feet (McKechnie, 2023). Psoriasis affecting the fingernails can also be problematic and can occur alone or alongside psoriasis at other sites. In rare cases of severe disease psoriasis causes a widespread erythematous rash (commonly affecting the scalp) which is life threatening due to potential complications.

Other forms are shown in Table 1.

Prevalence

Prevalence rates are difficult to accurately determine because those with mild symptoms may self-treat and never seek medical advice. In the UK, approximately 1.3-2.2% of people are affected by the condition, and the majority of these are white Caucasian, with males and females equally affected, (Knott, 2021). Published data on the prevalence of psoriasis worldwide suggest its occurrence varies between 0.9% and 11.4%, but in most developed countries it appears to affect between 1.5 and 5% (WHO 2016). Plaque psoriasis accounts for 90% of all cases of psoriasis with the majority presenting before the age of 35 (Knott, 2021).

Pathophysiology

The underlying processes leading to the development of psoriasis remains poorly understood. The process appears to be highly complex and is thought to be influenced by multiple factors including environmental, genetic, and immunological. It is thought that the epidermis is infiltrated by large numbers of activated T cells, which are inappropriately induced to produce cytokines, that stimulate inflammatory cell infiltration (leading to erythema) and keratinocyte proliferation, causing scales to develop as the stratum corneum is shed from the skin (Thomson I. 2020). People affected by psoriasis have an increased production of skin cells, normally made, and replaced every 3 to 4 weeks, but in psoriasis this process takes only 3 to 4 days, resulting in a build-up of skin cells and the development of the scaly patches associated with the disease (PCDS 2023).

Signs and symptoms

Chronic plaque psoriasis, the commonest variant is seen as skin lesions which are well demarcated and salmon pink in colour and have a symmetrical distribution (Raharia et al., 2021). The most frequent symptoms experienced are (WHO, 2016):

• Scaling of the skin: 92%
• Itching 72%
• Erythema 69%
• Fatigue 27%
• Swelling 27%
• Burning sensation 20%
• Bleeding 20%

Table 2 gives some information relating to symptoms associated with other forms.

Impact on quality of life

Psoriasis is a cause of emotional distress. The condition can affect the mental health of those affected, leading to time off work or school and avoidance of social engagements. Hedemann et al (2022) found psoriasis patients to be 1.5 times have more likely to show depressive symptoms and experience a higher prevalence of anxiety symptoms (20–50%) than individuals without psoriasis, with schizophrenia (2.82%) and suicidal ideation (12.7%) also found to be more prevalent among psoriasis patients than among the general population.

Causes

Both inherited and genetic factors are thought to play a role. Although the role that genetics play is unclear, the condition is thought to run in families and statistics suggest that a third of those affected have a first degree relative with the condition (Weigle and Mcbane, 2013). Psoriasis can also occur following skin injury. This is known as the Koebner phenomenon. Guttate psoriasis occurs after streptococcal infection of the upper respiratory tract, (most commonly tonsilitis) and symptoms are self-limited, but can recur following a recurrence of a streptococcal infection (Kamiya et al., 2019).

Trigger factors

Multiple factors have been studied to determine triggers which may cause a flare up or worsening of the problem. The following have been shown to have a possible influence (PCDS, 2023).

• Stress: This is thought to be strongly associated with psoriasis
• Alcohol: Moderate to large amounts of alcohol consumption may not only aggravate psoriasis but may also make it more difficult to treat.
• Obesity and smoking: Both are associated with a poor response to treatment and smoking is associated with pustular psoriasis.
• Hormonal changes: Menopause and pregnancy, may be factors. In some patients, psoriasis may improve in pregnancy but then worsens again after the delivery.
• HIV: This is associated with severe psoriasis and/or psoriasis that is hard to control.
• Medications: Some medications are known to affect psoriasis (e.g., Hydrochloroquine and lithium. Beta blockers and non-steroidal anti-inflammatory drugs (naproxen or ibuprofen) can make psoriasis worse in some patients.
• Skin injury: Psoriasis can sometimes develop at sites where there has been injury or trauma to the skin Multimorbidity

In recent years, it has become evident that psoriasis can extend beyond the skin and has been found to be associated with a variety of other conditions. Approximately 75% of patients will have at least one comorbid condition, but many with have multiple comorbidities (Lebwohl MG, Bachelez H, Barker J, et al. 2014). Individuals with psoriasis are more likely to suffer from obesity, cardiovascular disease, non-alcoholic fatty liver disease, diabetes, and metabolic syndrome than the general population, with rates being especially elevated in those with more severe psoriasis (Takeshita et al., 2017). Approximately 1 or 2 out of ten people develop pain and inflammation of some joints, known as psoriatic arthritis (McKechnie, 2023).

Diagnosis

Diagnosis is usually made on clinical examination and tests are rarely needed. Occasionally a biopsy may be useful if the diagnosis is in doubt.

Differential diagnosis

• Eczema: This is an inflammatory skin condition, characterised by itchy dry skin and may be easier to distinguish from chronic plaque psoriasis because of the lack of demarcation.
• Seborrheic dermatitis: Can have a greasy scale which is more diffuse than seen in psoriasis and can sometimes have a similar appearance to facial or scalp psoriasis. (Thaci et al, 2020)

Treatment and management

There is no available treatment which will completely cure psoriasis and most patients will need repeated courses of treatment when a flare up occurs. The aim is to minimise the rash and its symptoms, and options will depend on the effect achieved as well as patient preferences, as what may suit one person will not suit others. Topical treatments are first line and the choice will depend on the site and extent of the problem, the patient's preference, and product availability.

Common treatment options

Emollients:

Emollients form the mainstay of treatment and should be used continuously even when the problem is under control. They have a calming soothing effect and available as creams, lotions and ointments and they help to keep the skin soft, soften any patches of hard skin and are also useful for minimising itch and removing scales. More information is shown in Table 3. More potent treatments are as follows: (McKechnie, 2023)

First line treatments

Vitamin D based treatments

These include calcipotriol, calcitriol and tacalcitol). Available as creams, ointment, lotions and as a scalp application. Vitamin D based products are often combined with a steroid (e.g., calcipotriol/betamethasone). Adverse effects include skin irritation, soreness and itch which occurs in 1 in 5 users but usually settles after a treatment break. (McKechnie D. 2023)

Steroid creams and ointments

These reduce inflammation and can be used on the scalp and face. Milder options are recommended for these areas and in the skin flexures if these areas are also affected, and are used short term only because long term use may cause atrophy of the skin. Gradually tapering the frequency of topical corticosteroids after symptoms improve, is recommended but symptoms often return weeks to months after discontinuation (Weigle N, Mcbane S. 2013). Dithranol and tar preparations which were once popular choices are used are less frequently as they are associated with staining and skin irritation (Raharia A, Mahil SK, Barker JN. 2021). There are now newer applications such as plasters which are useful for small joints such as fingers and toes. Topical calcineurin inhibitors may be used second line for treatment of moderate to severe eczema and choices are: (NICE, 2023)

• Tacrolimus 0.03% and 0.1 % ointments licensed for use in children 2 years of age or older and for adolescents and adults of 16 years or older (0.1%)
• Pimecrolimus 1% cream, licenced for children over 3 months of age and older, adolescents and adults

Other treatment options may be needed for severe or difficult to treat psoriasis. These are shown in Table 4.

Complications

Psoriatic arthritis (swelling pain and joint stiffness), is estimated to affect up to 30% of people with psoriasis, although in most cases the psoriasis precedes the development of joint problems by up to 10 years (Raharia et al., 2021). The underlying cause is poorly understood, but most commonly affects the fingers and toes) (McKechnie, 2023). Skin infections can also occur because of scratching. The area will be red and inflamed with exudate or crusting and may require antibiotic treatment. In addition, because of the distressing nature of the condition, anxiety and depression are possible as those affected my avoid interaction with others leading to social isolation.

Prognosis

Prognosis is difficult to predict because of the variable nature of the disease and irregular pattern to flare ups. Some patients may be fortunate and have months or in some cases, years before a flare up occurs, other requiring treatment more frequently. Plaque psoriasis has been shown inn some studies to resolve completely in 1 in 3 people (McKechnie, 2023). Those who develop psoriasis at a young age are thought to have a more severe form of disease. Guttate psoriasis usually resolves within a few months of onset but there is a risk of later development of chronic plaque psoriasis.

Referral criteria

Referral is recommended for the following patients:

• If the diagnosis is uncertain
• Severe extensive psoriasis
• Patients not responding to treatment
• Any child or young adult presenting with symptoms
• Specialist referral to rheumatology if psoriatic arthritis is suspected

Conclusion

Psoriasis is a complex disease which has several forms and can occur anywhere on the body in varying degrees of severity. It often follows a relapsing and remitting course and because of its often-unsightly appearance it can be extremely distressing for those affected. There is no cure, and treatment aims to reduce the symptoms and is often needed at intervals when recurrence occurs. Early recognition and treatment are the key to better outcomes and there are several other treatment options if first line choices fail to achieve the desired effect. It is hoped that this article has given nurses and non-medical prescribers an insight in to this unpleasant skin disease and given them more confidence in recognising and treating it with the aim of improving quality of life for all those affected.