The timing of dialysis initiation affects the incidence of renal replacement therapy.

BACKGROUND Variations in the timing of dialysis initiation may explain some geographical variations in renal replacement therapy (RRT) incidence, but this effect has never been quantified. METHODS Using data from the French Renal Epidemiology and Information Network registry, we quantified the association between RRT incidence in 2006-07 and median estimated glomerular filtration rate (eGFR) values before starting dialysis at the administrative district level with geographically appropriate methods. RESULTS Crude RRT incidence varied from 80.4 to 238.6 pmi between administrative districts, and median eGFR at dialysis initiation from 5.9 to 11.8 ml/min/1.73 m(2). Age- and sex-adjusted RRT incidence, associated with a 1.2-ml/min/1.73m(2) increase in median eGFR, rose 8% (4-13%) before and 9% (5-13%) after controlling for the effect of nine potential socioeconomic and medical risk factors. CONCLUSION The impact of increased eGFR at initiation should be taken into account in guidelines recommending earlier dialysis start.