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Psoriasis treatments


Psoriasis affects about 2% of Caucasian populations, and first line treatments include topical preparations like steroid creams and tar. Where topical treatments fail, systemic treatments are used. These include phototherapy with ultraviolet B, or with ultraviolet A in combination with psoralens (photochemotherapy). Oral retinoids such as acitretin or etretinate, or even cyclosporin A may be used.

Which is the most effective? A systematic review [1] may help in choosing treatments and organising programmes.

Review

The searching strategy for this review was exhaustive. Studies reporting on the ability to induce remission in adult patients with chronic plaque-type psoriasis were selected, irrespective of randomisation. Combination therapies were not examined, nor conditions other than chronic plaque psoriasis. Studies which used obsolete or extreme dosing schedules were also omitted.

Even so, this left 665 studies (with 48 of them duplicated). Only one third of these were randomised, but there was information on 13,700 patients.

Outcomes

Treatment outcome was documented by the ability of the treatment to induce remission. This was graded as clearance (95-100% improvement in outcome parameter compared with baseline), good response (75-100% improvement), moderate response (50-75% improvement) and poor response (<50% improvement). Outcome parameters often used were psoriasis area and severity index, average global scores, and percentage of body surface area involved.

Results

The results are shown in the Figure for five treatments. Most information was on photochemotherapy, where the weighted average clearance rate was 70%. Ultraviolet B was also good, but other treatments were less good at producing clearance.

Adverse effects

The number of reported adverse effects per week of treatment was generally low, and was higher with the retinoids acitretin and etretinate than with ultraviolet or cyclosporin. The major adverse effects were mucocutaneous. The number of patients who stopped treatment for any reason varied between 6% and 22% for the different therapies.

Comment

This type of analysis is clearly subject to bias, since it includes non-randomised studies. The authors point out their difficulty in ensuring that patients had similar degrees of severity of psoriasis. They also point out that the clear differences between phototherapy and oral treatments reflect the difference in treatment goals. With the former it is full remission, while with the latter it is to induce remission while keeping adverse effects to the minimum by using the lowest possible oral dose.

Despite these caveats, this is an interesting review which could form the basis of treatment guidelines while pragmatic studies comparing the different therapies in head-to-head comparisons are awaited.

Reference:

  1. PI Spuls, L Witkamp, PM Bossuyt, JD Bos. A systematic review of five systemic treatments for severe psoriasis. British Journal of Dermatology 1997 137:943-9.



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