The NOR-SWITCH Study

Inclusion Criteria:

1. A clinical diagnosis of either rheumatoid arthritis, spondyloarthritis, psoriaticarthritis, ulcerative colitis, Crohn's disease or chronic plaque psoriasis

2. Male or non-pregnant, non-nursing female

3. >18 years of age at screening

4. Stable treatment with innovator infliximab (Remicade) during the last 6 months

5. Subject capable of understanding and signing an informed consent form

6. Provision of written informed consent

Exclusion Criteria:

1. Major co-morbidities, such as severe malignancies, severe diabetic mellitus, severeinfections, uncontrollable hypertension, severe cardiovascular disease (NYHA class 3or 4) and/or severe respiratory diseases

2. Change of major co-medication during the last 2 months prior to randomization: RA, SpA and PsA: Initiation of systemic corticosteroids or synthetic DMARDs or othermedication which according to the investigator would interfere with the stability ofthe disease. UC and CD: Initiation of systemic corticosteroids or an immunosuppressant or othermedication which according to the investigator would interfere with the stability ofthe disease Psoriasis: Initiation of synthetic DMARDs or other medication whichaccording to the investigator would interfere with the stability of the disease

3. Inadequate birth control, pregnancy, and/or breastfeeding

4. Psychiatric or mental disorders, alcohol abuse or other substance abuse, languagebarriers or other factors which makes adherence to the study protocol impossible

5. Change in treatment with innovator infliximab (Remicade) during the last 6 months dueto disease related factors, not including dose/frequency adjustments due to drugconcentration measurements