Background/Purpose: In our earlier study of IgG4-related kidney disease (IgG4-RKD), we found that renal dysfunction, which was mostly attributable to IgG4-related tubulointerstitial nephritis, was significantly improved at 1 month after the start of corticosteroid therapy, but reached a plateau thereafter, and renal atrophy developed in many patients (Saeki, et al. Kidney Int 2013). Little is known about the appropriate initial corticosteroid dose for induction therapy or the long-term renal outcome in IgG4-RKD with renal dysfunction.

Methods: This retrospective cohort analysis evaluated the recovery of renal function during the initial 1 month of corticosteroid therapy, and the long-term course of renal function after treatment, in 41 patients with confirmed IgG4-RKD in whom the eGFR before corticosteroid treatment had been less than 60 ml/min. The patients were collected from 16 collaborating institutions in Japan between 2004 and 2013, and divided into two groups (group L, initial prednisolone dose <0.6 mg/kg/day; group H, >0.6 mg/kg/day).

Results: Among the patients, 88% were male, and the mean age at the time of diagnosis of renal disease was 66.6±9.3 years. Renal pathology data were available for 38 of the 41 patients, and all of them had the tubulointerstitial features characteristic of IgG4-RKD. One patient with renal failure in group L showed no recovery of renal function and maintenance hemodialysis became necessary within 1 month after the start of treatment. Except for this patient, eGFR data at 1 month after treatment were available for 31 patients (group L 17; group H 14). The initial prednisolone dose was 0.47±0.12 mg/kg daily in group L and 0.84±0.16 mg/kg daily in group H, being significantly lower (P<0.001) in the former. There was no significant inter-group difference in patient age, sex or pretreatment eGFR. In both groups, the pretreatment eGFR was significantly improved at 1 month after the start of corticosteroid therapy [30.5±15.7 to 41.8±14.9 ml/min in group L (p<0.05) and 32.7±13.8 to 46.6±17.0 mi/min in group H (p<0.05)], and the degree of improvement showed no significant inter-group difference. Fifteen of the 41 patients were followed up for over 36 months (39 – 210 months, median 56 months), and all of them had been maintained on low-dose prednisolone (5.1 ± 2.1 mg daily) at the last review. No patient showed progression to end-stage renal disease, and there was no significant difference in eGFR at the last review (45.1 ±11.3 ml/min) in comparison to that at 1 month after the start of treatment (42.5 ±12.8 ml/min).

Conclusion: In IgG4-RKD, prednisolone 0.5 mg/kg daily is sufficient for induction therapy, and the recovery of renal function during the first month of this treatment can be maintained for a long period on low-dose corticosteroid maintenance therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/recovery-of-renal-function-after-corticosteroid-therapy-for-igg4-related-kidney-disease/