#psoriasis - new guidelines for management.

Psoriasis is a frequent inflammatory dermatosis which affects 1 to 2% of the global population. It is more frequent in Europe, especially Scandinavia. It is less frequent in blacks and chineses and is a rarity in Ethnic American-Indian population. Its causes are both genetic (PSOR1 gene on chromosome 6) and environmental (guttate psoriasis for example has a specific infectious etiology (streptococcal pharyngitis).

Management Algorythm: 

Limited psoriasis (less than 20% of the body surface area)

• topical steroids +/- vitamin D analogues (calcipotriene or calcitriol). No more than 100g per week of the latter because of hypercalcaemia induction;
• intralesional steroids;
• coal tar: these can be used in combination with topical corticosteroids. There is no conclusive study regarding the theoretical increased risk of skin cancer related to this agent;
• anthralin: it is derived from chrysarobine. It is often useful when applied daily for short periods. It is nevertheless irritant and can stain clothes and tiles. It can be combined with phototherapy (Ingram regimen);
• retinoids: tazarotene.

Phototherapy

• Narrow Band UVB (311nm): start at 70% of the minimal erythemal dose. Increase weekly 10-30%. 3 to 5 sessions per week. Remission is usually achieved after 30-45 days.
• PUVA or topical PUVA: after oral intake or topical application of a psoralen. Dosage varies according to the phototype.
• Multiclear (localised UVA and UVB treatment).

“Classical” systemic treatments

• retinoids (acitretin);
• methotrexate (7.5-25mg per week) with folic acid (1mg/d);
• ciclosporine (3-5mg/Kg/d);
• fumaric acid.

“Biologic” systemic treatments

Indications:

1. no response to classical systemic treatments or contraindications to them;
2. PASI (Psoriasis Area Severity Index) more or equal 15.

Short term response rates

-Adalimumab:

1. 70% of treated individuals achieve an improvement of PASI 70
2. 45% of treated individuals achieve an improvement of PASI 90
3. in both cases, the dosage is of 40mg every 2 weeks, after an induction dosa of 80mg

-Etanercept:

1. 35% of treated individuals achieve an improvement of PASI 70 and 10% have an improvement of PASI 90 after a dosage of 2 times 25mg per week.
2. 50% of treated individuals achieve an improvement of PASI 70 and 20% have an improvemnet of PASI 90 after a dosage of 2 times 50mg per week.

-Infliximab: for a dosage of 0.5mg/Kg at weeks 2, 4 and 6

1. 80% of treated individuals achieve an improvement of PASI 70.
2. 40% of treated individuals achieve an improvement of PASI 90.

-Ustekimumab: for a dosage of 45mg every three months:

1. 70% of treated individuals achieve an improvement of PASI 70.
2. 40% of treated individuals achieve an improvement of PASI 90.

To summarize:

Infliximab achieves the fastest results but it requires an intravenous infusion every 6 weeks;

With ustekimumab, the improvement of PASI 90 is maintained 76 weeks after initiation of treatment in 63% of patients at a dosage of 90mg and in 45% of patients at a dosage of 45mg;

Adalimumab remains efficient 2 years after initiation of treatment.

How to start a biologic?

1. it must have no response to other systemic agents, the severity of PASI must be at least 15;
2. which one to chose: adalimumab (anti-TNF), infliximab (anti-TNF), etanercept (anti-TNF)m, ustekimumab (anti IL-12): no real guidelines exist. Personal experience is therefore a must.

Topical agents to relieve symptoms

1. keratolytics for hyperkeratosis
2. 2-5% salicylic acid (up to 20% concentration in palmar and plantar locations)
3. emollients for parakeratosis
4. anthralin, topical steroids, vitamin D analogues and phototherapy for psoriasiform hyperplasia.