Design: Retrospective cohort with systematic review and meta-analysis of observational studies
Population: 311 kidney transplant recipients with IgA nephropathy from six cohorts
Primary outcome: IgA nephropathy recurrence in the allograft by native-biopsy crescents
Effect: RR 1.53 (0.40–5.90); recurrence in 23%

A study in the Journal of Nephrology, published on 22 October, combined a Lausanne transplant cohort of 63 patients with IgA nephropathy and five other cohorts, totalling 311 patients, of whom 23% had recurrence in the graft.

Crescents in the native kidney biopsy, present in 12% to 62% across cohorts, were not significantly associated with recurrence (risk ratio 1.53, with a very wide confidence interval). Crescents remain a marker of faster progression in native kidneys, especially when they involve more than a quarter of glomeruli, but this analysis did not find that they predict what happens after transplant.

For transplant counselling, the presence of crescents in the original biopsy should not on its own be presented as raising recurrence risk. The data are small and observational, so the question is not closed.

Do not counsel IgA nephropathy patients that native crescents alone raise their recurrence risk after transplant.
Continue to treat crescents as a marker of faster progression in native kidneys.
Monitor for recurrence after transplant with urinalysis and proteinuria checks, whatever the native histology.
Evidence comes from 311 patients in observational cohorts.

Why it matters

It separates a marker of native progression from transplant recurrence risk, which affects counselling.

The statistics, in plain English

A risk ratio of 1.53 with a 95% CI of 0.40 to 5.90 is consistent with crescents lowering, not affecting or substantially raising recurrence risk. The study cannot rule out an effect; it can only say one was not found.