Spondyloarthritis is a rheumatic condition characterized by arthritis/enthesitis and inflammatory back pain, sometimes in combination with extra-articular manifestations (psoriasis, inflammatory bowel disease, uveitis).  Therapeutic options are extensively studied for axial involvement, whereas treatment of peripheral arthritis is limited to methotrexate/sulfasalazine, and in a limited group of patients TNF-inhibition.  Previous research from our department demonstrated that early treatment with TNFi resulted in fast remission-induction (vs. placebo) and that it was possible to stop chronic treatment in more than 50% of patients.  In this research-project we want to compare TNFi to standard methotrexate/sulfasalazine with the aim om reaching "drug-free" remission.  Multiple paraclinical research investigations (synovial biopsy, epigenetic analysis) as well as a complete pharmaco-economic evaluation will be coupled onto this clinical trial.