MPO and vasculitis: If it is true that seronegative patients have more limited disease and less frequently a kidney involvement (19), their prognosis is not necessarily good: while a Chinese multicentre retrospective study found a better overall survival in negative patients as compared to MPO- and PR3-ANCA patients (20), on the contrary, in the French Vasculitis Study Group Registry, ANCA-negative and ANCA-positive patients have similar relapse free survival and overall survival after statistical adjustments (19).