Tonsillectomy reduces recurrence of IgA nephropathy in mesangial hypercellularity type categorized by the Oxford classification

BACKGROUND: In patients with IgA nephropathy (IgAN), recurrence after steroid pulse therapy is associated with reduced renal survival. However, the predictors of recurrence have not yet been clarified. METHODS: All patients who received 6-month steroid pulse therapy from 2004 to 2010 in our four affiliated hospitals and achieved a reduction of proteinuria to <0.4 g/day 1 year after treatment were retrospectively evaluated. The primary outcome was proteinuria ≥1.0 g/day during follow-up or additional antiproteinuric therapy. Two histological classifications were evaluated, the Oxford Classification with a split system and Japanese histological grades (HGs) with a lumped system. RESULTS: During a median follow-up of 3.4 years, 27 (26.7 %) of the 101 patients showed recurrence. Multivariate analysis showed that HG was the only significant predictor of recurrence, with HG 2+3+4 vs HG 1 having a hazard ratio of 7.38 (95 % confidence interval 1.52–133). Furthermore, in patients with mesangial hypercellularity according to the Oxford Classification, cumulative rate of recurrence-free survival was greater in patients with steroid therapy plus tonsillectomy compared with those who received steroid therapy alone (Log-rank test, P = 0.022). However, this association was not observed in patients without mesangial hypercellularity. CONCLUSIONS: HG is a novel predictor of recurrence after steroid pulse therapy in patients with IgAN. Moreover, the combination of steroid pulse therapy plus tonsillectomy may indicate a lower risk of recurrence in patients with mesangial hypercellularity, as defined by the Oxford Classification. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10157-015-1170-7) contains supplementary material, which is available to authorized users.