In the two large cohort studies, the Japanese RemIT-JAV-RPGN study (our previous study) [17] and RAVE study [10], TIMP-1 levels were a useful biomarker for distinguishing mildly or highly active AAV from remission 6 months after the initiation of remission-induction therapy regardless of differences in the population, such as AAV type, ANCA type, and treatment. This evidence concerns the gene TIMP1 and rapidly progressive glomerulonephritis.