Although renal prognosis and mortality is different among the underlying glomerulonephritides, corticosteroid-based immunosuppressive therapy is their main treatment modality and, therefore, they face the same clinical target, how to maximize the benefit of immunosuppressive therapy and minimize their disadvantages. The aims of the multicenter prospective cohort study, Japan Nephrotic Syndrome Cohort Study (JNSCS), are to provide the basic epidemiological date in primary CFTR modulator nephrotic syndrome in Japan, including the renal

prognosis and all-cause mortality, the response to the modern immunosuppressive practice patterns, and adverse events associated with these immunosuppressive therapy. JNSCS started in 2008 and 396 patients with primary nephrotic syndrome in 57 hospitals were enrolled during 3 years’ entry

period between 2008 and 2010. Diagnosis of glomerular diseases are minor change disease (MCD, n = 165 [41.6%]) and membranous nephropathy (MN, n = 158 [39.9%]), Rapamycin focal segmental glomerulosclerosis (FSGS, n = 38 [9.6%]), IgA nephropathy (n = 15 [3.8%]), membranoproliferative glomerulonephritis (n = 9 [2.3%]), non-IgAN mesangial proliferative glomerulonephritis (n = 7 [1.8%]), extracapillary proliferative glomerulonephritis (n = 2 [0.5%]) and intracapillary proliferative glomerulonephritis (n = 2 [0.5%]). Median age was 42 (interquartile range 26, 61) years in MCD, 66 (59, 75) years in MN, 62 (29, 73) in FSGS, and 58 (45, 71) in others. Male gender was 57.6%, 53.8%, 65.8%, and 57.1% in MCD, MN, FSGS, and others, respectively. Until December 2012, 359 (90.7%) patients received immunosuppressive therapy, including 162 MCD patients (98.2%), 136 MN patients (86.1%), 35 FSGS patients (92.1%), and 26 other patients (74.3%). Besides oral prednisolone (PSL), major initial immunosuppressive agents within 1 month of the immunosuppressive therapy were intravenous methylprednisolone (29.0%, 18.5%, 28.6%, and 50.0% in MCD, MN, FSGS, and others, respectively) Olopatadine and cyclosporin (14.8%, 45.2%, 42.9%, and 23.1% in MCD, MN, FSGS, and others, respectively). In contrast, only a few patients received cyclophosphamide

(0.6%, 4.4%, 0.0%, and 11.5% in MCD, MN, FSGS, and others, respectively), which KDIGO guideline 2012 recommended as the first-line immunosuppressive agent for MN. Interestingly, use of immunosuppressive agents were substantially different geographically. During median 2.3 years (interquartile range, 1.9–3.0) of observational period, cumulative probabilities of complete remission of proteinuria defined as <0.3 g/day of urinary protein, <0.3 urinary protein/urinary creatinine ratio, or negative or trace of dipstick urinary protein after initiation of immunosuppressive therapy (n = 359 [90.7%]) or kidney biopsy if no immunosuppressive therapy (n = 39 [9.3%]) were 0.85, 0.89, 0.93, and 0.95 at 2, 6, 12, and 24 months in MCD, 0.08, 0.27, 0.53, and 0.68 in MN, 0.32, 0.46, 0.58, and 0.65 in FSGS, and 0.09, 0.21, 0.42, and 0.