This is an observational, prospective (study following participants forward in time) study to assess safety and efficacy of infliximab injection under post-marketing use and identify problems related to adverse events in participants with ankylosing spondylitis (chronic inflammatory condition affecting the axial joints), rheumatoid arthritis (chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures), psoriasis (scaly skin rash) and psoriatic arthritis (a type of inflammatory arthritis associated with psoriasis). Participants with rheumatoid arthritis will receive 6 doses of infliximab 3 milligram per kilogram (mg/kg) as an intravenous infusion (a fluid or a medicine delivered into a vein by way of a needle) at Week 0, 2, 6 and will be observed for 30 weeks; and those with ankylosing spondylitis, psoriasis and psoriatic arthritis will also receive 6 doses of injection and will be observed for 24 to 30 weeks. Efficacy will be evaluated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), Psoriasis Area and Severity Index (PASI), swollen joint counts and tender joint count. Participants' safety will be monitored throughout the study.
