Early compensatory increase in single-kidney estimated GFR after unilateral nephrectomy is associated with a lower long-term risk of estimated GFR decline.

Background and hypothesis: A more pronounced short-term increase in single-kidney GFR (ΔskGFR) has been associated with better long-term kidney function in living kidney donors. Whether this also applies to non-donors is unknown. We evaluated whether ΔskGFR is associated with long-term risk of eGFR decline in individuals undergoing unilateral nephrectomy.

Methods: This study included 1777 participants from the SCREAM cohort who underwent radical unilateral nephrectomy in Stockholm between 2006 and 2021. The ΔskGFR was calculated as the early (1-6 months) post-nephrectomy eGFR minus 50% of the pre-nephrectomy eGFR. Multivariable Cox regression was used to study the association between Δsk-GFR and the subsequent risk of progressive eGFR decline, defined as composite of an eGFR decline >30% compared to the early (6 months) post-nephrectomy eGFR or kidney failure.

Results: Mean age at nephrectomy was 68 ± 11 years, 40% were female, 92% had kidney cancer, and median (IQR) pre-nephrectomy eGFR was 76 (61-89) ml/min/1.73 m2. Median Δsk-GFR was 11 (7-20) ml/min/1.73 m2. Pre-nephrectomy determinants of Δsk-GFR were age (inverse association) and pre-nephrectomy eGFR (positive association). During a median follow-up of 5 years (range 0.6-15 years), 178 participants developed progressive eGFR decline. Individuals with a Δsk-GFR above the median had a lower rate of progressive eGFR decline (adjusted HR: 0.58, 95% CI: 0.42-0.80), compared to those with a Δsk-GFR below the median, independent of baseline eGFR and age.

Conclusions: A stronger increase in single-kidney eGFR early after unilateral nephrectomy was associated with a lower long-term risk of progressive eGFR decline. Evaluation of Δsk-GFR could help identify patients at higher risk of progressive kidney function decline following unilateral nephrectomy.