Association between the time of initial relapse and subsequent relapses in patients with childhood-onset idiopathic nephrotic syndrome.

Background: Nephrotic syndrome relapse within 6 months is a known risk factor for steroid-dependent nephrotic syndrome/frequently relapsing nephrotic syndrome (SDNS/FRNS), but the risk of early development of SDNS/FRNS and initiation of immunosuppression therapy remains unknown.

Methods: Patients with childhood-onset idiopathic nephrotic syndrome who had the first relapse within 6 months were enrolled. We analyzed the relationship between the time of the first relapse or the time of initial remission and incidence of SDNS/FRNS or initiation of immunosuppression therapy.

Results: Forty-five patients were enrolled. Twenty out of 23 patients (87%) with the first relapse within 30 days after discontinuing initial steroid therapy experienced a second relapse within 30 days after discontinuing steroid therapy. Additionally, most patients in this group (96%) experienced a second relapse within 6 months after the onset and were diagnosed as SDNS/FRNS at this time. In this group, the incidence of SDNS/FRNS development within 6 months was 96%. In contrast, the incidence of SDNS/FRNS development within 6 months was 18% in patients with the first relapse more than 30 days after steroid discontinuation. The incidence of initiation of immunosuppressive agents within 6 months was 83% in the former group and 14% in the latter group.

Conclusions: Most patients with the first relapse within 30 days after discontinuing steroid therapy developed SDNS/FRNS and were administered immunosuppressive agents within 6 months. Thus, it might be reasonable to start immunosuppression therapy in this group without waiting for the second relapse.