[Psoriatic arthritis: what the dermatologist needs to know, Part 2]. 
This review aims to cover all aspects related to the treatment of psoriatic arthritis and the evaluation of the response to treatment.  We define the various evaluation methods currently used to assess response to treatment in patients with psoriatic arthritis and the complementary examination techniques used to ensure adequate follow-up.  These tools enable both the dermatologist and the rheumatologist to carry out an ongoing evaluation of the clinical course, severity, and prognosis of the disease.  The treatment lines proposed by the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis and the Spanish Society of Rheumatology are discussed.  Emerging strategies for treating this condition and improving prognosis are examined.