Dr Iain Henderson discusses the SIGN recommendations on diagnosis and treatment of patients with psoriasis and psoriatic arthritis and when individuals should be referred

Psoriasis is one of the major inflammatory skin diseases encountered in general practice. It is a T-cell mediated autoimmune disorder influenced by genetic, immunological, systemic, and environmental factors. It affects approximately 1.5%–3% of the population;1 35% of patients have a family history and identical twin studies show a concordance of 80%.2 Approximately 20% of patients with psoriasis may also have psoriatic arthritis.3

Psoriasis is uncommon below the age of 10 years;4 75% of cases present before the age of 40 years, with two peaks: one occurring at the age of 16 years (for females) or 22 years (for males) and a second peak at the age of 60 years (females) or 57 years (males).5 The mean age of onset is 33 years of age.4


The negative impact of psoriasis and psoriatic arthritis on health-related quality of life has been shown to be comparable to other medical conditions, such as cancer, depression, diabetes, and ischaemic heart disease.6 As a result of the visibility of even mild to moderate psoriasis (e.g. on the face, scalp, and hands), prevalence rates of co-morbidities and conditions such as depression, high stress levels, social stigmatisation, and employment issues are high in affected patients and may not be directly proportional to the severity of the disease.7,8 Joint swelling and deformity with subsequent physical disability due to psoriatic arthritis can also cause feelings of stigmatisation.9

The need for a guideline

Both psoriasis and psoriatic arthritis can vary in severity. Mild psoriasis can be treated with topical therapies in primary care but severe forms need prompt and often intensive therapy usually in secondary care. This could be in the form of outpatient phototherapy and systemic, biologic, or inpatient treatment. Psoriatic arthritis can manifest itself in a variety of ways and can be difficult to recognise, so referral from primary to secondary care may be delayed because of diagnostic uncertainty.

Additionally, the GP may be unaware of locally available treatments; even with the variety of treatments available, safe and effective control is not always achieved and there is no standard therapeutic approach. This can lead to dissatisfaction and disengagement of the patients.7

Over the past 20 years there has been a greater understanding of the cellular, molecular, and genetic mechanisms that cause the underlying inflammatory processes and there have been many new developments in the treatment of these conditions. SIGN recently published a guideline on Diagnosis and management of psoriasis and psoriatic arthritis in adults (SIGN 121), which provides recommendations based on current evidence for best practice.10

The guideline also includes a care pathway for patients with psoriasis and psoriatic arthritis, which covers the patient journey between primary and secondary care and the assessments and treatments that occurs at each step (see Figure 1, below).10

Diagnosis of psoriasis

Chronic plaque psoriasis
The diagnosis of chronic plaque psoriasis is usually straightforward—well-demarcated red plaques with adherent silvery white scale on the surface. It affects many parts of the body and, in particular, the scalp and extensor surfaces of limbs; scaling is reduced on flexural and genital areas. The differential diagnosis includes tinea, eczema, lupus erythematosus, and lichen planus.10

Guttate psoriasis
Guttate psoriasis can appear rapidly as multiple small papules of psoriasis over a wide area of the body. Differential diagnosis for this type of psoriasis includes viral exanthemas, pityriasis rosea, and drug eruptions.10

Generalised pustular and erythrodermic psoriasis
Generalised pustular psoriasis is characterised by the development of multiple sterile non-follicular pustules within plaques or on red tender skin. Erythrodermic psoriasis is indicated by generalised redness of the skin. Fortunately both of these conditions are rare; they do, however, require emergency referral to specialist care.10

Diagnosis of psoriatic arthritis

Psoriatic arthritis is frequently undiagnosed; in a recent European study of 1511 patients with plaque psoriasis who attended a dermatology clinic, 20.6% were found to have psoriatic arthritis; this condition was newly diagnosed in 85% of the cases.3 Healthcare professionals who provide care to patients with psoriasis therefore need to be aware of the association of psoriatic arthritis in this condition.

There are various subtypes of joint involvement in psoriatic arthritis including:10

  • distal arthritis
  • spondyloarthritis
  • symmetric polyarthritis
  • asymmetric oligoarthritis (fewer than 5 joints)
  • arthritis mutilans.

Patients can present with a mixture of subtypes and the pattern of disease may vary over time. Other features of psoriatic arthritis include dactylitis (sausage fingers), tenosynovitis, and enthesitis.11

If early diagnosis of psoriatic arthritis is missed and the condition goes untreated it may progress and potentially worsen the patient’s quality of life and prognosis. However, the Guideline Development Group (GDG) was unable to identify any studies that demonstrated whether early compared with late diagnosis and treatment changed long-term outcome in terms of co-morbidities, joint damage, and disability.10 Any patient with suspected psoriatic arthritis should be assessed by a rheumatologist. Annual reassessment of patients with psoriasis for arthritis should be considered in primary care; this could be performed using a patient-administered screening questionnaire such as the Psoriasis Epidemiology Screening Tool (PEST) (see Figure 2, below).10

Patient review

As there is an increased risk of cardiovascular disease and diabetes in patients with severe psoriasis or psoriatic arthritis, annual evaluation should include:10

  • body mass index
  • diabetes screening
  • blood-pressure measurement
  • lipid profile
  • smoking status.

Most studies show an association between alcohol consumption and psoriasis, but do not show causality.12 The SIGN guideline recommends giving lifestyle advice to patients with psoriasis or psoriatic arthritis regarding regular exercise, weight management, moderation of alcohol consumption, and cessation of smoking.10

Both psoriasis and psoriatic arthritis can affect all aspects of quality of life with potentially profound psychosocial implications. Although, the GDG was unable to identify any good quality studies on the effectiveness of psychological therapies or stress management in this group of patients, assessment of depression and other psychosocial issues should be included in the annual review, with referral to mental health services as appropriate. The Patient Health Questionnaire (PHQ-9) and the Dermatology Life Quality Index (DLQI) are two examples of assessment questionnaires.10

Figure 1: Psoriasis and psoriatic arthritis care pathway10


DMARD=disease-modifying anti-rheumatic drug; DLQI=Dermatology Life Quality Index

Figure 1: Psoriasis and psoriatic arthritis care pathway (continued)10


Scottish Intercollegiate Guidelines Network. Diagnosis and management of psoriasis and psoriatic arthritis in adults. SIGN 121. Edinburgh: SIGN; 2010. Reproduced with kind permission of the Scottish Intercollegiate Guidelines Network


Treatment in primary care

Many patients with psoriasis can be managed in primary care. The mainstay of treatment for mild psoriasis is topical therapy. No studies on the effectiveness of emollients were identified but their regular use should be considered to reduce fall of scales and help other symptoms such as itch.10 The other main groups of topical therapies are the vitamin D analogues, corticosteroids, coal tar preparations, tazarotene, and dithranol.

A comparison of topical therapies is shown in Table 1 (see below).10

Plaque psoriasis
Based on appraisal of a good quality Cochrane review,10 it was recommended that plaque psoriasis should be treated with short intermittent use of a potent topical steroid or a combined potent corticosteroid plus calcipotriol ointment to achieve rapid improvement.10

A vitamin D analogue is recommended for long-term topical treatment of plaque psoriasis because of concerns over the long-term adverse effects of prolonged use of potent and very potent corticosteroids. If this therapy is ineffective or not tolerated, coal tar preparations, tazarotene, and dithranol are possible alternatives.10

Guttate psoriasis
Patients with guttate psoriasis who do not respond to topical therapy should be considered for early referral for phototherapy. There was insufficient evidence to support recommendations concerning antistreptococcal interventions for the treatment of guttate psoriasis.10

Scalp psoriasis
Approximately 50%–80% of people with psoriasis may have scalp involvement,14 which can be the sole manifestation of the disease. It can present as ‘increased dandruff’ to very thick and large pieces of scale stuck to hair shafts (pityriasis amiantacea). Initial treatment with overnight application of salicylic acid, or coal tar or oil preparations (e.g. coconut oil or olive oil) is recommended to remove thick scale.10

The SIGN guideline recommends short-term use of potent topical corticosteroids or a combination of a potent corticosteroid and a vitamin D analogue in scalp psoriasis.10

Face and flexures
Short-term use of moderate potency corticosteroids is recommended for psoriasis of the face and flexures. If these are ineffective, vitamin D analogues or tacrolimus ointment should be used for intermittent use; coal tar can also be considered for this purpose. Dithranol and topical retinoids tend to be too irritating in these areas.10

Nail psoriasis
Up to 90% of patients with psoriasis can have nail changes at some point in their life;15 however, nail psoriasis is generally refractory to topical treatment. One systematic review concluded that there was no evidence to recommend one treatment above another, but topical corticosteroids, salicylic acid, calcipotriol, or tazarotene used alone or in combination can be considered.10

To improve concordance a patient should be offered a follow-up appointment within 6 weeks of initiating or changing treatment to assess efficacy and acceptability. The number of treatments per day should be kept to a minimum.10

Other interventions
There was insufficient evidence to support recommendations concerning antistreptococcal interventions for the treatment of guttate psoriasis or any complementary therapy for treatment of psoriasis or psoriatic arthritis.10


Referral to a consultant dermatologist should be considered under the following circumstances:10

  • Diagnostic uncertainty
  • Extensive disease
  • Occupational disability or excessive time lost from work or school
  • Involvement of sites that are difficult to treat (e.g. face, palms, or genitalia)
  • Failure after use of appropriate topical treatment for 2–3 months
  • Adverse reactions to topical treatment
  • Severe or recalcitrant disease
  • DLQI score >5.

Referral to a nurse-led clinic or a dermatology nurse specialist should be considered in patients if a diagnosis of psoriasis has previously been established in secondary care and where the following has taken place:10

  • Relapse following topical treatment
  • Refractory scalp psoriasis
  • Request for further counselling and/or education including demonstration of topical treatment
  • Topical treatment/phototherapy according to protocols, nurse competencies, and local arrangements.

Referral to rheumatology
Although no criteria for referral to rheumatology for use in primary care were identified, it is appropriate to refer patients if joint swelling or dactylitis is present, or when spinal pain with significant early morning stiffness is present.10

Occupational health services
The impact of psoriasis and psoriatic arthritis is often felt in employment and therefore effective communication between the treating physician and the occupational healthcare professional is recommended for decisions and advice regarding work.10

Patient information

Provision of information is an integral part of any consultation and the SIGN guideline makes the following recommendations:10

  • Active involvement of patients in managing their care should be encouraged
  • Patients should receive information about their diagnosis, treatment options, and the correct application of topical treatments after their first consultation and on the first use of new treatment
  • Verbal information should be reinforced by written material and by further sources of information (e.g. support groups or appropriate websites) (see Box 1).

Figure 2: PEST screening questionnaire for psoriatic arthritis (in people with psoriasis)10

Score 1 point for each question answered in the affirmative. A total score of 3 or more is indicative of psoriatic arthritis (sensitivity 0.92, specificity 0.78, positive predictive value 0.61, negative predictive value 0.95)
  No Yes
Have you ever had a swollen joint (or joints)?    
Has a doctor ever told you that you have arthritis?    
Do your fingernails or toenails have holes or pits?    
Have you had pain in your heel?    
Have you had a finger or toe that was completely swollen and painful for no apparent reason?    

Scottish Intercollegiate Guidelines Network. Diagnosis and management of psoriasis and psoriatic arthritis in adults. SIGN 121. Edinburgh: SIGN; 2010. Reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

In the drawing below, please tick the joints that have caused you discomfort (i.e stiff, swollen, or painful joints)


Reproduced with permission of Philip Helliwell, University of Leeds
PEST=psoriasis epidemiology screening tool

Table 1: Comparison of topical therapies10
Therapy Efficacy Suitability in
inducing remission
Suitability as maintenance treatment Patient
Coal tar ? ?
Corticosteroids* and fixed combinations with
a vitamin D analogue
???? ??? ? ??
Dithranol ?? ?? —†
Tazarotene ?? ?? ?? ??
Vitamin D analogues ??? ??? ??? ??
*Potent or very potent corticosteroid; †More suitable as an inpatient Scottish Intercollegiate Guidelines Network. Diagnosis and management of psoriasis and psoriatic arthritis in adults. SIGN 121. Edinburgh: SIGN; 2010. Reproduced with kind permission of the Scottish Intercollegiate Guidelines Network


As SIGN is part of NHS Quality Improvement Scotland, its guidelines examine the implementation of the recommendations in Scotland rather than the whole of the UK. The responsibility of implementing national guidelines lies with each NHS Board and is an essential aspect of clinical governance.10

The SIGN GDG gave consideration to the potential impact of recommending that patients with psoriasis have an annual review in primary care.10 Based on an estimated Scottish population prevalence of psoriasis of 1.5% to 3%1 and consultation rates of affected patients,16 there would be approximately 63 additional consultations per general practice per year in Scotland.10 The impact could be partially offset if the planned universal annual health checks to all people aged 40–74 years were used to undertake the recommended annual review of patients with psoriasis.10,17 The main barrier to undertaking this annual review in Scotland and in the rest of the UK is its absence in the quality and outcomes framework payments to GPs.


The SIGN guideline for the diagnosis and management of psoriasis and psoriatic arthritis in adults provides recommendations based on current evidence for best practice. It covers:

  • early diagnosis of psoriatic arthritis
  • screening for co-morbidities
  • assessment of disease severity
  • topical, systemic, and biological treatments, phototherapy and non-pharmacological treaments
  • referral pathway
  • provision of patient information.

Adhering to the SIGN guideline recommendations on the management of psoriasis will not ensure a successful outcome in every case, but it will help to improve the patient’s understanding of the disease and the treatment options, which in turn should improve concordance.

Box 1: Sources of further information
  • Psoriasis is a common disease that often needs a combination of GP and specialist care
  • Local referral and care pathways forged between GPs and specialists can ensure the most cost-effective treatment for patients with psoriasis
  • A community GPwSI or specialist nurse service could help manage patients effectively and avoid the cost of tariff prices for outpatient appointments
  • A psoriasis care pathway should include indications for referral to rheumatology services and appropriate investigations where arthropathy is suspected
  • Dermatology outpatient services are back in the mandatory payment-by-results tariff for 2011
  • Tariff prices 2011–2012 (road-test tariff):a
    • Dermatology = £119 (first outpatient), £67 (follow up)
    • Rheumatology = £260 (first outpatient), £107 (follow up).
  1. Griffiths C, Barker J. Pathogenesis and clinical features of psoriasis. Lancet 2007; 370 (9583): 263–271.
  2. Gawkrodger D. Dermatology. An illustrated textbook. 4th Edition. China: Churchill Livingston, 2007.
  3. Reich K, Kruger K, Mossner R, Augustin M. Epidemiology and clinical pattern of psoriatic arthritis in Germany: A prospective interdisciplinary epidemiological study of 1511 patients with plaque-type psoriasis. Br J Dermatol 2009; 160 (5): 1040–1047.
  4. Schofield J, Grindlay D, Williams H. Skin conditions in the UK: a health care needs assessment. Centre of Evidence Based Dermatology, University of Nottingham, 2009.
  5. Henseler T, Christophers E. Psoriasis of early and late onset: characterization of two types of psoriasis vulgaris. J Am Acad Dermatol 1985; 13 (3): 450–456.
  6. Rapp S, Feldman S, Exum M et al. Psoriasis causes as much disability as other major medical diseases. J Am Acad Dermatol 1999; 41 (3 Pt 1): 401–407.
  7. Stern R, Nijsten T, Feldman S et al. Psoriasis is common, carries a substantial burden even when not extensive, and is associated with widespread treatment dissatisfaction. J Investig Dermatol Symp Proc 2004; 9 (2): 136–139.
  8. Kimball A, Jacobson C, Weiss et al. The psychosocial burden of psoriasis. Am J Clin Dermatol 2005; 6 (6): 383–920.
  9. Mease P, Menter M. Quality-of-life issues in psoriasis and psoriatic arthritis: outcome measures and therapies from a dermatological perspective. J Am Acad Dermatol 2006; 54 (4): 685–704.
  10. Scottish Intercollegiate Guidelines Network. Diagnosis and management of psoriasis and psoriatic arthritis in adults. SIGN 121.Edinburgh: SIGN, 2010. Available at:www.sign.ac.uk/guidelines/fulltext/121/index.html
  11. Gladman D, Antoni C, Mease P et al. Psoriatic arthritis: epidemiology, clinical features, course, and outcome. Ann Rheum Dis 2005; 64 (2): ii14–ii17.
  12. Higgins E, Peters T, du Vivier A. Smoking, drinking and psoriasis. Br J Dermatol 1993; 129 (6): 749–750.
  13. Mason A, Mason J, Cork M et al. Topical treatments for chronic plaque psoriasis. Cochrane Database Syst Rev 2009; (2): CD005028.
  14. Papp K, Berth-Jones J, Kragballe K et al. Scalp psoriasis: a review of current topical treatment options. J Eur Acad Dermatol Venereol 2007; 21 (9): 1151–1160.
  15. De Berker D. Management of nail psoriasis. Clin Exp Dermatol 2000; 25 (5): 357–362.
  16. NHS National Services Scotland, Information Services Division Scotland, Practice Team Information. Psoriatic arthropathy and psoriasis. IR2010-01840. Excel spreadsheet emailed to SIGN, 26 July 2010.
  17. Scottish Government website. Universal health checks planned. www.scotland.gov.uk/News/Releases/2010/03/22081937 (accessed 18 January 2011). G