Renal vasculitis causes damage to the small blood vessels inside the kidneys and – when untreated – leads to a rapid loss of kidney function. Therapies that block the immune system to switch off the vasculitis process are available but can lead to serious infections and other long term complications. As vasculitis is uncommon, it has been difficult to establish the most effective and safest treatment, because studies have often been too small to detect these effects reliably. One way to try to overcome this, is to combine the results of similar studies and, in September 2015, Giles Walters and his colleagues in Australia did this by updating the Cochrane Review of studies of treatments to induce and maintain disease remission for renal vasculitis. Giles tells us what they found in this podcast.