First, the investigators hypothesize that initiation of a combination therapy with golimumab + MTX will be safe and superior to MTX alone in MTX-naïve PsA patients, as assessed by the percentage of patients achieving Disease Activity Score (the investigators hypothesize that more patients with the early combination treatment will respond (according to Disease Activity Score (DAS), American college of Rheumatology (ACR), or Psoriatic Arthritis Response Criteria (PsARC) responses) and achieve a state of Low Disease Activity (LDA) or Minimal Disease Activity (MDA) than patients on MTX alone.