While doing some research, I found a nice write up about PsA...
Biologics for Psoriasis and Psoriatic Arthritis (Adalimumab, Etanercept, Golimumab, Infliximab, Ustekinumab) National PBM Criteria for Use – Monograph with Literature Review June 2013 VA Pharmacy Benefits Management Services, Medical Advisory Panel, and VISN Pharmacist Executives
Quote: PsA Q4: In patients with psoriatic arthritis, is there a difference between biologic monotherapy and combination biologic-nonbiologic therapy in terms of efficacy, effectiveness, safety, or tolerability?
Recent evidence suggests that methotrexate is not efficacious and is not a DMARD in PsA (3 RCTs).
There is insufficient evidence to determine the efficacy and safety of biologic-nonbiologic combination therapy relative to biologic monotherapy.
Cited
Biologics for Psoriasis and Psoriatic Arthritis (Adalimumab, Etanercept, Golimumab, Infliximab, Ustekinumab) National PBM Criteria for Use – Monograph with Literature Review June 2013 VA Pharmacy Benefits Management Services, Medical Advisory Panel, and VISN Pharmacist Executives