A Study of Ixekizumab (LY2439821) Versus Adalimumab in Participants With Psoriatic Arthritis

Inclusion Criteria: * Presence of established diagnosis of active psoriatic arthritis for at least 6 months, and currently meets Classification for Psoriatic Arthritis (CASPAR) criteria * Active PsA defined as the presence of at least 3 (out of 68) tender and at least 3 (out of 66) swollen joints * Presence of active plaque psoriasis with a BSA ≥3% * Men must agree to use a reliable method of birth control or remain abstinent during the study * Women must agree to use reliable birth control or remain abstinent during the study and for at least 12 weeks after stopping treatment * Have had an inadequate response when treated with 1 or more conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) Exclusion Criteria: * Current or prior use of biologic agents for treatment of Ps or PsA * Evidence of active inflammatory arthritic syndromes or spondyloarthropathies other than PsA * Have participated in any study with interleukin 17 (IL-17) antagonists, including ixekizumab * Serious disorder or illness other than psoriatic arthritis * Serious infection within the last 3 months * Active Crohn's disease or active ulcerative colitis * Active vasculitis or uveitis * Diagnosis of or history of malignant disease \<5 years prior to randomization * Women who are breastfeeding