Recently new and promising therapeutic agents have been introduced in the Rheumatology world. However most of the data regarding response to treatment, outcomes, adverse effects and costs,come from randomized clinical trials, the follow up of patients recruited in randomized clinical (RCT) trials, or pharmacovigilance systems sponsored by the industry. While RCTs provide evidence of efficacy, what is really needed is information on effectiveness, or on the extent to which treatments work in the community of patients who actually use them. This is better achieved by conducting community cohort studies.