A Study of Ixekizumab (LY2439821) in Participants Aged ≥18 Years With Moderate-to-Severe Plaque or Active Psoriatic Arthritis in India

Inclusion Criteria: All participants: * Male or nonpregnant, nonbreastfeeding female participants. For PsO Participants: * Present with chronic PsO based on a confirmed diagnosis of chronic PsO vulgaris for at least 6 months prior to baseline * Have ≥10% Body Surface Area (BSA) of psoriasis at screening (Visit 1) and baseline * Have both an static Physician's Global Assessment (sPGA) score of ≥3 and Psoriasis Area and Severity Index (PASI) score ≥12 at screening and baseline For PsA Participants * Have a diagnosis of active PsA for at least 6 months (based on a detailed medical history provided by the patient, and a physical exam by the Study Investigator, and/or other evidence such as that provided by joint x-rays, that establishes a history consistent with a diagnosis of active PsA of at least 6 months' duration) and currently meet the Classification for PsA (CASPAR) criteria. * Have active PsA defined as the presence of at least 3/68 tender and at least 3/66 swollen joints, as determined by the Tender and Swollen Joint Count Assessment Form at screening and baseline. * Presence of active PsO or a documented history of psoriasis. Exclusion Criteria: * Have previously completed or withdrawn from this study, participated in any other study with ixekizumab, or have participated in any study investigating other IL-17 antagonists. * Have a history of drug-induced PsO. * Have a known allergy or hypersensitivity to any biologic therapy that would pose an unacceptable risk to the patient if participating in this study. * Had any major surgery within 8 weeks prior to baseline (Week 0; Visit 2), or will require such during the study that, in the opinion of the investigator in consultation with Lilly or its designee, would pose an unacceptable risk to the participant * Have diagnosis or history of malignant disease within the 5 years prior to baseline * Have any other active or recent infection within 4 weeks of baseline For PsO Participants: * Have received systemic non-biologic PsO therapy (within 4 weeks prior to baseline) * Have pustular, erythrodermic, and/or guttate forms of PsO * Had a clinically significant flare of PsO during the 12 weeks prior to baseline (Week 0). * Have allergy to rubber or latex. For PsA Participants: * Have used conventional synthetic disease-modifying antirheumatic drug (csDMARDs) other than methotrexate (MTX), leflunomide, sulfasalazine, or cyclosporine in the 8 weeks prior to baseline * Have received treatment with interleukin (IL)17 or IL-12/23 targeted Mab therapy * Are currently receiving treatment with any biologic or small molecule therapy for PsA or PsO, including investigational therapies (such as, but not limited to, a tumor necrosis factor inhibitor (TNFi), IL-1 receptor antagonists, IL-6 inhibitor, anti-IL12/23p40, T cell or B cell targeted therapies, phosphodiesterase (PDE) 4 inhibitors, or Janus Kinase (JAK) inhibitors), or have received denosumab. * Have had surgical treatment of a joint within 8 weeks prior to baseline or will require such up to Week 24.