I recently came across the the following statistics from The Psoriasis Education Program (www.psoriasisinfo.ca):

Conclusion: Therapy with TCM has several advantages. It is
effective and shows excellent safety in most patients with psoriasis.
Remission seems to be long lasting. In addition, treatment with TCM is
less costly for the patient when compared with narrow-band UVB,
psoralen plus UVA (PUVA), retinoids, ciclosporin, alefacept, and other
new biologic agents.