AIM The aim of our study is to assess the benefits and potential adverse effects of a prolonged initial corticosteroid regimen across four Italian regions, for the treatment of the initial episode of INS. The results will be compared with data obtained retrospectively from the analysis of a control group of INS, treated with a short steroid regimen during the previous 3 years in the same area. In addition genetic studies will be undertaken with the aim of evaluating pharmacogenetics and pharmacodynamics of steroid treatment with the ultimate goal to individualise treatment in single patients.