Prognostic value for long-term graft survival of estimated glomerular filtration rate and proteinuria quantified at 3 months after kidney transplantation

Abstract

Background. The estimated glomerular filtration rate (eGFR) measured at 1 year is the usual benchmark applied in kidney transplantation (KT). However, acting on earlier eGFR values could help in managing KT during the first post-operative year. We aimed to assess the prognostic value for long-termgraft survival of the early (3 months) quantification of eGFR and proteinuria following KT. Methods. The 3-, 6- and 12-month eGFR using the Modified Diet in Renal Disease equation (eGFRMDRD) was determined and proteinuria was measured in 754 patients who underwent their first KT between 2000 and 2010 (with a mean follow-up of 8.3 years) in our centre. Adjusted associations with graft survival were estimated using a multivariable Cox model. The predictive accuracy was estimated using the C-index and net reclassification index. These same analyses were measured in a multicentre validation cohort of 1936 patients. Results. Both 3-month eGFRMDRD and proteinuria were independent predictors of return to dialysis (all P<0.05) and there was a strong correlation between eGFR at 3 and 12 months (Spearman's q=0.76). The predictive accuracy of the 3-month eGFR was within a similar range and did not differ significantly from the 12-month eGFR in either the derivation cohort [C-index 62.6 (range 57.2-68.1) versus 66.0 (range 60.1-71.9), P=0.41] or the validation cohort [C-index 69.3 (range 66.4-72.1) versus 71.7 (range 68.7-74.6), P=0.25]. Conclusion. The 3-month eGFR was a valuable predictor of the long-term return to dialysis whose predictive accuracy was not significantly less than that of the 12-month eGFR in multicentre cohorts totalling >2500 patients. Three-month outcomes may be useful in randomized controlled trials targeting early therapeutic interventions.