A Study to Evaluate the Safety of Remsima® SC in the Treatment of RA, AS, PsA and Ps

Inclusion Criteria: a.Patients with active RA having inadequate response to disease modifying antirheumatic drugs (DMARDs), including methotrexate (MTX) or b.Patients with severe, active and progressive RA not previously treated with MTX or other DMARDs c.Patients with severe, active AS who have responded inadequately to conventional therapy or d.Patients with active and progressive PsA when the response to previous DMARDs has been inadequate or e.Patients with moderate to severe plaque Ps who failed to respond to or who have a contraindication to, or are intolerant to other systemic therapy including cyclosporine, methotrexate or psoralen ultra-violet A. * The Remsima® SC group will include all patients who meet one of the following classification at the time of enrolment: 1. Biologic-naïve patients or 2. Patients continuing on infliximab IV including Remsima® IV who will switch to Remsima® SC or 3. Patients continuing on biologic treatments other than infliximab who will switch to Remsima® SC or 4. Patients continuing on Remsima® SC (having commenced Remsima® SC treatment prior to enrolment) * The Remsima® IV group will include all patients who meet one of the following classification at the time of enrolment: 1. Biologic-naïve patients or 2. Patients continuing on biologic treatments other than infliximab who will switch to Remsima® IV or 3. Patients continuing on infliximab IV including Remsima® IV who will switch to or maintain Remsima® IV \* Note: Switching from Remsima® SC to Remsima® IV is not allowed. Exclusion Criteria: 1. Patients with a history of hypersensitivity to murine, chimeric, human, or humanized proteins or any of the excipients of Remsima® SC or Remsima® IV, whichever the patients are going to be treated in each treatment group, listed in the Summary of Product Characteristics (SmPC) of each product. 2. Patients with any reported contraindications for Remsima® SC or Remsima® IV according to the SmPC of each product. 1. Patients with active tuberculosis (TB) 2. Patients with inactive (latent) TB who are not willing or not compliant with TB prophylaxis or a past diagnosis of TB without sufficient documentation of complete resolution following treatment. 3. Patients with severe infection such as sepsis, abscesses and opportunistic infections (including, disseminated herpes simplex virus, candidiasis but not limited to) 4. Patients with a current or past history of chronic infection with human immunodeficiency virus (HIV), hepatitis B and hepatitis C 5. Patients with moderate or severe heart failure (New York Heart Association \[NYHA\] class III/IV) 6. Patients for whom there are investigator concerns about treatment with tumour necrosis factor alpha (TNF-α) inhibitor, such as a history of any malignancy within the previous five years prior to enrolment, may be excluded at the investigator's discretion.