Recommendations for a patient-centered approach to the assessment and treatment of scalp psoriasis: a consensus statement from the Asia Scalp Psoriasis Study Group

Background: International consensus statements on the management of scalp psoriasis are available, but no such recommendations exist for Asia. Methods: The Asia Scalp Psoriasis Study Group (ASPSG) met in May 2011 to review the epidemiologic pattern of scalp psoriasis in Southeast Asia and to develop Asia-specific recommendations for its management. Results: The overall prevalence of psoriasis in Asia is <0.3%, but 75–90% have scalp involvement, whether isolated or with lesions elsewhere, which can negatively impact quality of life (QoL). Treatment decisions should be based primarily on objective disease severity, but should also take account of patient QoL. Psychosocial support and more aggressive treatment should be offered to all patients with moderate to severe QoL impairment. Topical therapy is indicated first-line in all patients, with combination therapy (corticosteroid + calcipotriol), more occlusive formulations, keratolytics, and very potent corticosteroids for patients needing greater or faster efficacy. Systemic therapies, light or laser treatments should be reserved for patients with severe and recalcitrant disease. Conclusions: The ASPSG recommends a patient-centered approach to scalp psoriasis management, consistent with the international consensus statements. Asian physicians should also consider patient QoL, prior treatment response, formulation preferences, likely adherence, cost, time available for self-management, and potential adverse events.

Keywords: guidelines; consensus; scalp psoriasis; Asia; topical; quality of life

Although psoriasis can affect any area of the skin, the scalp is one of the most frequently affected areas, with data in European populations indicating that up to 80% of patients with psoriasis have scalp involvement ([[1]]). Scalp psoriasis is characterized by papulosquamous lesions with silver-white scaling that often extend beyond the hairline onto the face ([2]). Currently, there is a range of international guidelines on the management of psoriasis ([[3]]), including some from Asia (Philippines, Malaysia, Taiwan, Hong Kong) ([[10]]). However, few of these guidelines are specific to the management of scalp psoriasis ([[4], [7]]), which presents unique challenges for treatment. Compared with skin in other areas of the body, the scalp is rendered relatively inaccessible to topical therapies or ultraviolet (UV) light from standard cabinets because of hair ([14]). Moreover, scalp and facial skin may be more susceptible to the irritant effects of treatment ([14]).

In recent years, there has been an increase in the number of topical and systemic therapies available for the treatment of scalp psoriasis. Although the range of available therapies provides clinicians with more options for scalp psoriasis management, it complicates therapeutic decision-making in the absence of evidence-based guidelines. Ideally, recommendations for Asian patients with psoriasis should be based on published data from Asia, but the number of Asian publications is limited.

On May 26, 2011, the Asia Scalp Psoriasis Study Group (ASPSG) met in Seoul, Korea, to discuss the development of regional recommendations for the management of scalp psoriasis. Rather than evidence-based guidelines, the Group developed consensus-based recommendations from an analysis of regional and international guidelines and published data. Consensus was reached via roundtable discussion and then follow-up correspondence. A consensus recommendation was included only when members unanimously agreed.

Epidemiologic data within the general population show that the prevalence of psoriasis varies among different ethnic groups ([15]), and it is evident from population-based studies that psoriasis tends to affect Asian populations less than European populations ([[15]]). The prevalence of psoriasis based on population-based studies is approximately 2% for northern European populations ([15]) versus 0.2% to 0.3% for Chinese/Taiwanese populations (Table I) ([[17]]).

Table I. Prevalence of psoriasis from a selection of general population-based studies conducted in Asia and reviews of international prevalence data ([15-19]).

The prevalence of psoriasis does not appear to be related to latitude or relative humidity ([16]), suggesting that genetic or other environmental factors determine differences in international disease prevalence.

Despite the high incidence of scalp involvement in patients with psoriasis, there is a paucity of published epidemiologic data specifically on scalp psoriasis, particularly in Asian patients. Published and unpublished data from Vietnam, Malaysia, the Philippines, and Taiwan indicate that between 1.4% and 2.7% of patients presenting to outpatient dermatology clinics have psoriasis and, among these, between 75% and 90% have scalp involvement (Table II) ([[20]]). This is consistent with data from the Malaysian Psoriasis Registry (MPR), which reported scalp involvement in 78.8% of patients with psoriasis ([22]). From these data, it appears that the rate of scalp involvement in Asia is similar to or higher than in Western European populations, where it is reported in between 50% and 80% of psoriasis patients ([[1], [23]]).

Table II. Prevalence of psoriasis and scalp involvement in the Philippines, Vietnam, Malaysia and Taiwan.

It has been suggested that age at onset of psoriasis has a bimodal distribution, and that patients who develop psoriasis before the age of 40 years are more likely to have severe, recurrent disease associated with human leukocyte antigens (HLAs) than patients who develop psoriasis after the age of 40 years ([[15], [24]]). In a US study, around 35% of psoriasis patients developed lesions before the age of 20 years ([25]). Malaysian patients in the MPR were aged between 2 and 80 years at the onset of psoriasis ([22]), but onset at younger and older ages have been reported ([21]). Girls tend to develop psoriasis at a younger age than boys do ([26]). Lesions on the extremities are more common in children than adults ([27]), but scalp lesions are present in between 47% and 53% of children with psoriasis ([[26]]). In fact, the scalp is often the first site of disease involvement in children ([26]).

Psoriasis has a strong genetic component which, in combination with environmental and lifestyle variables, influences the clinical presentation and severity of psoriasis within different populations. In particular, the HLA-Cw6 allele is associated with an increased risk of developing psoriasis, particularly early-onset disease, in Western and Asian populations ([[15], [29]]). However, this allele appears to be less prevalent among Asian populations (0–5%) ([[15], [29]]) than in Western populations (9%) ([15]). Moreover, a study in Han Chinese patients (n = 679) found that scalp involvement was significantly more prevalent in patients who were negative for HLA-Cw6 than in those who were positive for HLA-Cw6 ([29]), which differs from the situation in Caucasian patients.

In Caucasian populations, it is generally agreed that early-onset psoriasis is associated with the presence of disease-associated HLAs, but there is a subset of Asian patients who do not predominantly manifest early-onset disease and who have a haplotype containing HLA-Cw1 and HLA-B46 ([15]). This haplotype is specific to Southeast Asian and Taiwanese Chinese populations ([[15], [31]]).

Primarily because of the visibility of the lesions and the associated itch, scalp psoriasis is an important psychosocial handicap that has a substantial impact on the quality of life (QoL) of patients ([[2], [23]]). Most studies on QoL in patients with psoriasis have been conducted in Western countries, and these studies show that mental health and social functioning are impaired in psoriasis patients more so than physical health ([32]). In addition to physical discomfort, patients with psoriasis report impaired emotional functioning, a negative body image and self-image, and limitations in their daily activities, social contacts, and work ([32]). Psoriasis in visible areas of the body appears to have a greater impact on a patient's QoL than psoriasis severity per se ([33]).

A study conducted in Singapore involving 93 Chinese patients with psoriasis found that those with cosmetic involvement, such as lesions on the scalp, reported significantly greater levels of anxiety on the Hospital Anxiety Depression Scale (HADS) compared with patients with less obvious lesions ([34]). Overall, it was concluded that psychosocial morbidity is a clinically important concern in patients with psoriasis ([34]). More recently, a retrospective chart review of 480 Taiwanese patients seen by traditional Chinese medicine doctors, in whom the scalp was the most common initial site of psoriatic lesions (49.8%), found that psoriasis had a moderate to extremely large effect on QoL, as assessed with the dermatology life quality index (DLQI) in 67% of patients ([35]). Consistent with studies in Western countries, disease severity and younger age both had a negative impact on QoL in this study ([35]). Although women tend to have more invested in their appearance and to be less satisfied with general body image than men, gender was only weakly associated with QoL in the Taiwanese study, suggesting that ethnic or cultural factors may have a bearing on this finding.

Malassezia yeasts are found in areas rich in sebaceous glands such as the scalp ([36]), and overgrowth of the scalp with Malassezia species is a well-recognized feature of scalp psoriasis and seborrheic dermatitis ([2]). In one small European study, there were significant differences in the distribution of Malassezia species between healthy and psoriatic scalp and, furthermore, there were differences in the distribution of Malassezia species according to the severity of scalp involvement ([37]). It is possible that climate may have an influence on Malassezia-related diseases, with greater prevalence and more severe cases in tropical Southeast Asian climates ([38]), although other analyses have suggested no link between psoriasis prevalence and latitude or humidity ([16]). The prevalence and severity of scalp psoriasis in association with Malassezia scalp colonization in Southeast Asian populations may, therefore, be an interesting topic for future epidemiologic research. Currently, the data on the efficacy of antifungals to treat scalp psoriasis are contradictory ([1]).

Psoriasis severity is usually determined by the Psoriasis Area and Severity Index (PASI) ([39]). However, because this measure is weighted according to the percentage body surface area of involvement, it may underestimate the severity of scalp psoriasis if there are few lesions on other surfaces. A modified version of the PASI has been developed specifically for scalp psoriasis called the Psoriasis Scalp Severity Index (PSSI) ([40]). While these scoring systems have value in a clinical trial setting, they are not used routinely in clinical practice ([41]). Another measure more suited to routine clinical practice is the Physician Global Assessment (PGA) score ([42]). Physicians score psoriasis severity on a 7-point scale from 0 (clear skin) to 6 (severe psoriasis) ([42]). However, this scale does not include definitions for each level of severity ([41]).

The 2009 European consensus statement on scalp psoriasis management defines scalp psoriasis as mild, moderate or severe, based on both the extent of scalp involvement and the severity of lesions, and provides definitions for lesion severity based on the presence and severity of erythema, scaling and pruritus, and on the thickness of the lesions (Table III) ([7]). The ASPSG supports the use of this grading system to define disease severity, but stresses the importance of also taking into account the impact of scalp psoriasis on the patient's well-being.

Table III. Assessment of scalp psoriasis severity, as developed by the European Consensus meeting on the management of scalp psoriasis (7), and recommended by the Asia Scalp Psoriasis Study Group.

4 Reproduced with permission from the European Consensus Statement.

The ASPSG advocates a patient-centered approach to treatment, since patients with scalp psoriasis may have only a small proportion of their total body surface area affected, but the effects of social isolation and other QoL issues may be profound. However, the principal component of disease severity assessment should be the objective signs and symptoms of scalp psoriasis, with patient impact moderating treatment decisions, but not determining them. The rationale for this approach is to facilitate treatment decisions that take account of both the objective and subjective severity of scalp psoriasis.

The ASPSG recommends that physicians assess patient QoL at each visit. A range of QoL assessment instruments are available (Table IV) ([[43]]), and any one of these may be suitable, although psoriasis-specific measures will be the most sensitive ([44]). The pros and cons of these instruments have been reviewed in detail elsewhere ([[43], [46]]). Only one of the currently available instruments, the Scalpdex, is specific to scalp disease, and may be used to assess any dermatologic scalp condition ([45]). Scalpdex is a validated questionnaire consisting of 23 questions, and takes around 5–10 min for the patient to complete. Patients use a 5-point Likert scale to evaluate the impact of their scalp condition on each QoL parameter, as follows: 0 = "never,", 1 = "rarely," 2 = "sometimes," 3 = "often," and 4 = "all the time" ([45])".

Table IV. Instruments for measuring health-related quality of life in patients with psoriasis ([43-47]).

5 aVAS = Visual Analogue Scale; in EQ-5D, patients are asked to rate their overall health status on a 20 cm VAS, ranging from best to worst imaginable health.

QoL assessment tools were principally designed for use in clinical trials to evaluate the effect of treatment on patient well-being. As a result, categories of mild, moderate or severe impairment have not been defined. While no formal thresholds for severity exist for these instruments, the ASPSG suggests that physicians make a decision on the impact of scalp psoriasis (mild, moderate, or severe) based on the distribution of responses that patients provide to the statements in their chosen QoL instrument.

Topical treatment is the mainstay of treatment for scalp psoriasis, and is recommended as first-line therapy for all patients. A number of topical agents and formulations are available in Asia (Table V) ([[1], [14], [48]]). The choice of treatment will be determined by disease severity, patient preference, previous response, and cost.

Table V. Topical agents available in Asia to treat scalp psoriasis ([1-2, 14, 48]).

Most topical therapies have proven to be effective in the treatment of psoriasis, based on results from a Cochrane Collaboration meta-analysis, which analyzed data from randomized, placebo-controlled studies ([49]). Most classes of topical therapy were significantly more effective than placebo, with the exception of coal tar, which did not reach the threshold for statistical significance in this meta-analysis ([49]). However, only 18 of the 131 studies in the analysis were specifically on scalp psoriasis.

Topical corticosteroids have a rapid onset of effect and are available in a range of strengths and formulations ([1]). Short-contact formulations such as shampoos, lotions, foams and gels are preferred for patients with mild to moderate disease, and more occlusive formulations such as creams and ointments in those with moderate to severe disease ([7]). The lowest strength preparation for lesion clearance should be used, bearing in mind that high-potency steroids may be needed by patients with moderate to severe disease ([4]). Potent topical steroids can be associated with adverse events (e.g., skin atrophy, telangiectasia, striae) during long-term use, but these are generally rare on the scalp, because scalp skin is relatively thick and steroid absorption is limited by the presence of hair and sebum. Nevertheless, short-term treatment or intermittent long-term use of potent steroids is recommended ([4]).

Vitamin D3 analogs, most commonly calcipotriol (also called calcipotriene), are also available in solution, lotion or gel formulations for the topical treatment of psoriasis. Calcipotriol is the preferred vitamin D3 analog because it has far less effect (by a factor of 100- to 200-fold) than calcitriol on systemic calcium metabolism, resulting in a better safety profile ([2]). Vitamin D3 analogs are not associated with atrophy and may be used for long-term treatment ([4]), but patients should be counseled about the risk of irritation during the first few weeks of treatment ([4]).

The combination of the corticosteroid betamethasone with the vitamin D3 analog calcipotriol allows the use of lower doses of each, thereby maximizing efficacy and limiting the potential for adverse events ([4]). This combination is more effective than either of these agents as monotherapy ([[50]]), and is better tolerated than calcipotriol monotherapy ([[51]]). Compared with monotherapy, the onset of effect of betamethasone dipropionate plus calcipotriol is more rapid ([[50]]), and the combination has a more marked impact on QoL compared with calcipotriol monotherapy ([54]). Betamethasone plus calcipotriol is safe for long-term use, with no evidence of steroid-associated skin atrophy ([55]), and may therefore also be used as maintenance therapy.

Coal tar preparations are inexpensive and are suitable treatments for scalp psoriasis ([1]) if cost is an issue, but patients are often put off by their unpleasant odor, staining properties and messy application ([[4], [14], [48]]). Data from Thailand show that coal tar preparations are less effective than corticosteroids for the treatment of plaque psoriasis ([56]), and a UK study has demonstrated that scalp psoriasis is also less responsive to coal tar shampoo than to clobetasol shampoo ([57]).

Patients with significant scaling associated with moderate or severe scalp psoriasis may benefit from treatment with keratolytics, such as salicylic acid, prior to initiating other forms of topical therapy ([[2], [58]]).

Dithranol is an older form of treatment for psoriasis, but is now rarely used on the scalp, and should be reserved for more severe and treatment-resistant cases ([2]). Patient acceptability of dithranol is limited by the occurrence of a burning sensation after application ([2]), and because it may stain the skin ([1]) or hair ([2]), and is not easily washed out ([[1], [14]]).

There may also be a limited role for antifungal agents in the treatment of scalp psoriasis ([58]), based on the suggested etiologic role that overgrowth of Malassezia species plays in the development of both scalp psoriasis and seborrheic dermatitis ([2]). However, inconsistent efficacy of antifungals in the treatment of scalp psoriasis has been reported ([1]). Ketoconazole has anti-inflammatory effects in addition to antifungal activity ([59]), and may therefore be a suitable option in patients with mild psoriasis. However, antifungals are probably most suitable for patients with signs of sebopsoriasis or those who are immunocompromised.

Patients with moderate to severe scalp psoriasis, or those with mild disease whose QoL is more than mildly impacted, may be candidates for topical combination therapy. However, other than for corticosteroids plus vitamin D3 analogs, there is limited evidence surrounding the use of topical combinations for scalp psoriasis. One of the few studies showed that use of a coal tar shampoo along with a calcipotriol solution conferred a small, but statistically significant benefit on signs and symptoms of psoriasis compared with calcipotriol used in combination with a non-medicated shampoo ([60]).

Systemic therapies, such as methotrexate, acitretin, cyclosporine or biologic agents, are used in Asia to treat psoriasis. Biologics are newer agents and have a shorter track record of use and experience compared with oral systemic agents ([[4], [7]]). The limited data on the efficacy of biologics in Asian patients suggest a lower efficacy than in Europeans ([61]). This highlights the need for more study of biologic treatments within the Asian region. The use of systemic therapies may also be limited by restricted availability in some Asian countries ([61]), high cost ([7]), and the risk of infective complications, particularly the risk of hepatitis B or tuberculosis reactivation ([61]). For these reasons, the ASPSG recommends these treatments be reserved for step 2 therapy, in patients with severe and/or treatment-resistant scalp psoriasis, or in patients with pre-existing moderate to severe cutaneous psoriasis or psoriatic arthropathy.

Although phototherapy is an established treatment for psoriasis that is widespread or resistant to topical therapies, delivering UV rays to the scalp can be problematic because of the presence of hair ([[1], [4]]). Phototherapy tends to be poorly effective on unshaven scalps, is not universally available ([7]), and requires patients to attend clinics for treatment. Therefore, the ASPSG recommends that phototherapy be reserved for severe or treatment-resistant scalp psoriasis in patients who have access to this treatment.

A UVB comb has been successfully used to deliver UV rays directly to affected scalp, but the data come from small uncontrolled studies ([[1], [4]]). Excimer laser therapy appears to be more effective than narrow-band UVB therapy or pulsed-dye laser therapy ([62]). In addition, excimer laser treatment can be combined with topical psoralen and UVA irradiation (PUVA) to speed healing and reduce the cumulative UVA dose relative to PUVA alone ([62]). However, excimer laser therapy is not widely available or utilized in Asia because of the high cost.

The ASPSG has developed an algorithm for scalp psoriasis management in Asia (Figure 1), based on currently available treatments and other international consensus statements ([[4], [7]]). According to this algorithm, physicians should choose treatments corresponding to the objective disease severity as outlined in Table VI, but with the option of escalating treatment and providing additional psychosocial support based on the impact of psoriasis on the patient's well-being. All patients whose scalp psoriasis has moderate or severe impact on their QoL should be offered psychosocial support. For patients with mild to moderate disease whose QoL is severely impacted, clinicians should consider escalating treatment to the next recommended level.

Graph: Figure 1. Algorithm for treatment decision-making in scalp psoriasis based on disease severity, and impact on patient quality of life.

Table VI. Treatment recommendations for scalp psoriasis.

Table VI. Treatment recommendations for scalp psoriasis.

6 *As defined by the European Consensus Group (see Table III). However, patients with thin plaques but with >50% scalp involvement or those with thick scaly plaques but <50% scalp involvement may be upgraded to step 1b or 2 treatment. †Treatment choices based on objective scalp severity may be moved to a step higher if impairment of quality of life is severe, as shown in Figure 1. ‡If there are features of sebopsoriasis or the patient is immunocompromised.

Psoriasis treatments are often associated with poor patient adherence ([63]). The reasons for such poor adherence in psoriasis are unknown but may relate to a number of issues. First, patients may use their topical medication intermittently when symptoms are bothersome and stop using it when the symptoms improve; qualitative data suggest that intermittent use is more common than regular use of topical therapy ([64]). Second, patients may lack information on how to use their prescribed medicines correctly ([64]). Third, the patient may find the treatment inconvenient or poorly effective. Common reasons for poor adherence are the need for frequent applications, treatment taking up too much time, and the treatment not working as well as they had expected, usually because the response was not rapid enough. Other determinants of treatment success from a patient viewpoint are how well the treatment controls spread of lesions, reduces symptoms and improves the feel of their skin, how quickly it works and how long a positive effect is maintained ([65]). Fourth, the type of formulation may impact on adherence. When asked to rate the characteristics of different topical preparations for scalp psoriasis, patients rated side effects as having the most important impact on their use of a product, followed by the time needed to apply the medication and messiness ([66]). Foam or mousse preparations are liked by patients ([66]), but need to be applied twice daily and contain alcohol that may cause stinging ([7]). Patients may therefore prefer topical treatments that can be applied once daily and have a cosmetically acceptable vehicle. Some topical treatments (e.g., clobetasol or coal tar) are available as shampoos that have the advantage of good absorption after brief skin contact, and are liked by patients ([67]), but the coal tar preparations may cause staining of fabrics such as clothes or linens. Care should be taken to avoid contact with eyes when rinsing out steroid shampoos to minimize the potential for ocular injury ([67]).

For many patients in Asia, cost can be a significant hindrance to effective treatment. These patients may be restricted to using an inexpensive, but less effective therapy, such as coal tar preparations ([56]). However, cost considerations should include more than just the purchase price of treatment. There can be additional costs for the healthcare payer associated with monitoring adverse events (e.g., with methotrexate or cyclosporine) or for the patient associated with time away from work (e.g., to attend clinics for phototherapy) ([68]).

Based on available data, it appears that between 75% and 90% of Asian patients with psoriasis have scalp involvement. The ASPSG advocates a patient-centered approach to treatment, since patients with scalp psoriasis may have only a small proportion of their total body surface area affected, but the effects of social isolation and other QoL issues may be profound. Treatment of these patients should be individualized and based primarily on the objective severity of their disease. However, treatment decisions should also take account of the impact of scalp psoriasis on the patient's QoL. Physicians should offer psychosocial support to all patients whose QoL is moderately or severely affected by scalp psoriasis, and consider escalating therapy to a more aggressive level in these patients as well. Topical treatment is the mainstay of therapy for all patients. Considerations when choosing the appropriate treatment include: effectiveness, speed of response, patient preference, likely adherence, cost, time available for self-management, and potential adverse events. Careful patient education about how to use medications, expectations of efficacy and tolerability issues, and long-term management options will help to maximize adherence and therapeutic success.

The Asia Scalp Psoriasis Study Group meeting was funded by LEO Pharma. Dr. Frez received honoraria and travel grants from the following companies: LEO Pharma – Key Opinion Leader, Speakers' Bureau Asian Xamiol Study Group Chair, Janssen Pharmaceuticals – Asian Advisory Board, Ustekinumab, Speakers' Bureau, GSK-Stiefel – Speakers' Bureau, Galderma – Speakers' Bureau, and received honoraria, travel grant and research grant from Pfizer – Advisory Board, Speakers' Bureau. Dr. Tsai has conducted clinical trials, received speaking fees or received honoraria for serving as a consultant for Pfizer Pharmaceuticals Inc. (formerly Wyeth), Serono International SA (now Merck Serono International), UniPharma/Biogen Idec, Janssen-Cilag, LEO Pharma, Galderma, Tanabe Pharmaceuticals, GlaxoSmithKline, Novartis and Abbott. Dr. Pravit received travel grants and honoraria from LEO Pharma. Dr. Hazel Oon has received honoraria and acted as a speaker and/or investigator for LEO Pharma, Janssen Pharmaceuticals, Novartis and Galderma.

The authors would like to thank UBM Medica Asia Pte. Ltd., Singapore for assistance with the preparation of the manuscript. UBM Medica was funded by LEO Pharma for the editorial support.